TECHNICAL FIELD

The present invention relates to a solar energy system using molecular solar thermal energy storage (MOST).

The present invention relates to compounds having the capacity to store solar energy, to a method of storing solar energy by irradiating light or sunlight to a light-absorbing molecule which converts the molecule to its metastable photoisomer. The energy can subsequently be released by thermal activation or by the use of a catalyst.

BACKGROUND

Photoinduced isomerization of organic molecules is a possible way to store solar energy, to store the energy in the form of latent chemical bonds. A system of such organic molecules are called molecular solar thermal system (MOST), or alternatively solar thermal fuel system.

In these systems, a parent molecule is irradiated with light and transformed into a high energy metastable photoisomer. The photoisomer can then be converted back to the original parent compound when exposed to a suitable agent or condition. During the back conversion, the photoisomer releases the stored energy in the form of heat, which can then be collected and used in a suitable way.

The invention relates to a molecular solar thermal (MOST), or solar thermal fuel, wherein the parent molecule, a photochromic molecule, upon irradiation can generate a corresponding high energy metastable photoisomer.

The parent molecule is herein a norbornadiene (NBD), and the corresponding high energy metastable photoisomer is a quadricyclane (QC), a NBD-QC couple.

For optimizing a MOST system, there are some factors to elaborate with. These are: energy storage density, solar spectrum match, quantum yield of photoconversion, the half-life of the high energy isomer, related to the rate of conversion of the metastable photoisomer into the parent molecule. NBD compounds have previously been used in solar energy systems, described for example in US 4,446,041 and US 4,394,858.

Further NBD compounds, and NBD-QC couples are previously known, for example, by EP 2 842 959 A1. Herein, a complex phosphorous compound comprising a NBD structure is known. The compound therein disclosed are used as ligands in organic synthesis reaction using a complex catalyst. Methods for storing solar energy are described in JP S 60185064 and JP S 60185065. These systems use solar energy and the energy-carrying substances disclosed are NBD derivatives.

A solar energy collector is described in WO2016/097199 A1. This solar energy collector comprises an energy converter which in one embodiment can be a molecular solar thermal system (MOST).

In Lennartsson, A., et al., Tetrahedron Letters 56 (2015) 1457-1465, it is also described a wide range of MOST systems and applications thereof. Also Quant, M., et al., Chem. Eur. J., 2016, 22, 13265-13274, and Kuisma, M., et al., ChemSusChem, 2016, 9, 1 -10, disclose MOST systems based on NBD compounds.

However, there is a demand to find a more optimal MOST system, where the energy can be stored during a long time period. By the present invention, a number of NBD-QC couples have been found to show surprisingly attractive properties. The NBD-QC couples described herein may then be used for collecting and storing energy. SUMMARY

The present invention relates to compounds being norbornadiene

(NBD)/quadricyclane (QC) couples. The conversion from their metastable photoisomer to parent molecule is to be used for solar energy storage applications.

In an aspect of the invention the norbornadiene compound is a compound according to Formula I

Formula I

wherein

R ¹ represents a substituents selected from the group consisting of substituted phenyl, naphthyl, substituted naphthyl, heteroaryl, and substituted heteroaryl; wherein the substituted phenyl, substituted naphthyl, and substituted heteroaryl, are substituted at least in one of its ortho-positions; and are substituted with one or more substituents selected from the group of CN, C(Hal) ₃ , R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ ); or

R ¹ represents substituent selected from the group consisting of substituted naphthyl, and substituted heteroaryl, which is substituted at least in one of its ortho-positions with substituents forming steric bulk;

R ² represents aryl, substituted aryl, heteroaryl, and substituted heteroaryl, (which substituted aryl and substituted heteroaryl groups are substituted with one or more substituents selected from the group consisting of, CN, C(Hal)3, R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) _2J NH(R ³ )); CN; CO; COOR ⁴ ; COR ⁴ ; CON(R ⁴ ) ₂ ;

C = C(CN) _2;

R ³ independently represents C1-C10 alkyl, optionally substituted with Hal;

R ⁴ independently represents H, C1-C10 alkyl, optionally substituted with Hal; with the proviso that the compound is not

Bicyclo[2.2.1 ]hepta-2, 5-diene, 2,3-bis(2-methoxyphenyl)-;

Bicyclo[2.2.1 ]hepta-2, 5-diene, 2,3-bis(2-chlorophenyl)-;

Bicyclo[2.2.1 ]hepta-2,5-diene-2-carboxylic acid, 3-(1 -naphthalenyl)-, methyl ester;

Bicyclo[2.2.1 ]hepta-2,5-diene-2-carboxylic acid, 3-(2-chlorophenyl);

Bicyclo[2.2.1 ]hepta-2,5-diene-2-carboxylic acid, 3-(2-methoxyphenyl)-; Bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(2-nitrophenyl)-;

Bicyclo[2.2.1]hepta-2,5-diene-2-(2-chlorophenyl), 3-(2-chlorophenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(2-methoxyphenyl); Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(2-chlorophenyl); Bicyclo[2.2.1]hepta-2,5-diene-2-(4-pyridyl),3-(4-pyridyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(3-pyridyl),3-(3-pyridyl) ;

Bicyclo[2.2.1]hepta-2,5-diene-2-(2-pyridyl),3-(2-pyridyl) ;

Bicyclo[2.2.1]hepta-2,5-diene-2-(carboxy),3-(2-methyl phenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(carboxy),3-(2-methoxyphe nyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(carboxy),3-(2-chlorophen yl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(carboxy),3-(2-nitropheny l).

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-pyridyl),3-(4-methyl phenyl),

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-pyhdyl),3-(4-nnethoxyp henyl),

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-pyhdyl),3-(4-dinnethyl anninphenyl), Bicyclo[2.2.1]hepta-2,5-diene-2-(4-pyhdyl),3-(4-diethylannin phenyl), bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(2-chlorophenyl);

bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(2-methoxyphenyl)-;

bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(2-nitrophenyl)-;

bicyclo[2.2.1]hepta-2,5-diene-2-(2-chlorophenyl), 3-(2-chlorophenyl);

bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(2-thiophen);

bicyclo[2.2.1]hepta-2,5-diene-2-(4-cyanophenyl), 3-(2-thiophen).

An embodiment of the invention is the compound of Formula I wherein R ¹ represents substituent selected from the group consisting of substituted phenyl, naphthyl, substituted naphthyl; wherein the substituted phenyl, and substituted naphthyl, are substituted at least in one of its ortho-positions with one or more substituents selected from the group of CN, C(Hal)3, R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ );

R ² represents aryl, substituted aryl, heteroaryl, and substituted heteroaryl, (which substituted aryl and substituted heteroaryl groups are substituted with one or more substituents selected from the group consisting of, CN, C(Hal)3, R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) _2J NH(R ³ )); CN; CO; COOR ⁴ ; COR ⁴ ; CON(R ⁴ ) ₂ ; C=C(CN) ₂ ;

R ³ independently represents C1-C10 alkyl, optionally substituted with Hal; R ⁴ independently represents H, C1-C10 alkyl, optionally substituted with Hal. An embodiment of the invention is the compound of Formula I wherein the one or more substitiuents of R ¹ and R ² are selected from the group consisting of CN, C(F)s, R ³ , OR ³ , F, N0 ₂ , N(R ³ ) ₂ , NH(R ³ ).

In an embodiment of the invention, the R ¹ represents substituted phenyl, naphthyl, substituted naphthyl, heteroaryl, and substituted heteroaryl; wherein substituted phenyl, naphthyl, and heteroaryl, are substituted at least in its ortho-position; and are substituted with one or more substituents selected from the group of CN, C(Hal) ₃ , R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ ); or

R ¹ represents substituent selected from the group consisting of substituted naphthyl, and substituted heteroaryl, which is substituted at least in one of its ortho-positions with substituents forming steric bulk;

R ² represents aryl, substituted aryl, heteroaryl, and substituted heteroaryl, (which substituted aryl and substituted heteroaryl groups are substituted with one or more substituents selected from the group consisting of CN, C(Hal) ₃ , R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ )); CN; CO; COOR ⁴ ; COR ⁴ ; CON(R ⁴ ) ₂ ; C=C(CN) ₂ ;

R ³ independently represents C1 -C5 alkyl, optionally substituted with Hal;

R ⁴ independently represents H, C1 -C5 alkyl, optionally substituted with Hal;

Hal represents F or Cl.

Another embodiment includes the compounds as defined above, wherein R ¹ represents substituted phenyl, naphthyl, substituted naphthyl, heteroaryl, and substituted heteroaryl; wherein substituted phenyl, naphthyl, and heteroaryl, are at least in substituted in its ortho-position; and is substituted with one or more substituents selected from the group of CN, C(Hal) ₃ , R ³ , OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ); or

R ¹ represents substituent selected from the group consisting of substituted naphthyl, and substituted heteroaryl, which is substituted at least in one of its ortho-positions with substituents forming steric bulk;

R ² represents aryl, substituted aryl, heteroaryl, and substituted heteroaryl, (which aryl and heteroaryl groups are substituted with one or more

substituents selected from the group consisting of C(F) ₃ , R ³ , OR ³ , F, N(R ³ ) ₂ , NH(R ³ )); CN; COOR ⁴ ; Hal represents F or Cl;

R ³ independently represents C1 -C5 alkyl, optionally substituted with Hal;

R ⁴ independently represents H, C1 -C5 alkyl, optionally substituted with Hal; A further embodiment is the compound as defined above, wherein

Hal represents F;

R ³ independently represents C1 -C3 alkyl, optionally substituted with Hal; and R ⁴ independently represents H, C1 -C3 alkyl, optionally substituted with Hal. Another embodiment is the compound according to Formula I as defined above, wherein R ¹ represents substituent according to

Formula lla:

Formula lla;

Formula Mb;

wherein

R ^' represents R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ );

R ^" represents H, R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ );

R ¹ⁱ , R ^{1 ii} , R ¹ⁱⁱⁱ independently represent: H, R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ ), aryl;

or the 1 -naphthyl according to Formula Mb is optionally substituted with one or more of H, R ³ , OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ); R ² represents aryl, substituted aryl, heteroaryl, and substituted heteroaryl, (which aryl and heteroaryl groups are substituted with one or more

substituents selected from the group consisting of CN, C(Hal)3, R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ )); CN; CO; COOR ⁴ ; COR ⁴ ; CON(R ⁴ ) ₂ ; C=C(CN) ₂ wherein R ³ independently represents C1-C10 alkyl;

R ⁴ independently represents H, C1-C10 alkyl, optionally substituted with Hal; with the proviso that the compound is not:

Bicyclo[2.2.1 ]hepta-2, 5-diene, 2,3-bis(2-methoxyphenyl)-;

Bicyclo[2.2.1 ]hepta-2, 5-diene, 2,3-bis(2-chlorophenyl)-;

Bicyclo[2.2.1 ]hepta-2,5-diene-2-carboxylic acid, 3-(1 -naphthalenyl)-, methyl ester;

Bicyclo[2.2.1 ]hepta-2,5-diene-2-carboxylic acid, 3-(2-chlorophenyl);

Bicyclo[2.2.1 ]hepta-2,5-diene-2-carboxylic acid, 3-(2-methoxyphenyl)-;

Bicyclo[2.2.1 ]hepta-2,5-diene-2-carboxylic acid, 3-(2-nitrophenyl)-;

Bicyclo[2.2.1 ]hepta-2,5-diene-2-(2-chlorophenyl), 3-(2-chlorophenyl);

Bicyclo[2.2.1 ]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(2-methoxyphenyl); Bicyclo[2.2.1 ]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(2-chlorophenyl);

Bicyclo[2.2.1 ]hepta-2,5-diene-2-(4-pyridyl),3-(4-pyridyl);

Bicyclo[2.2.1 ]hepta-2,5-diene-2-(3-pyridyl),3-(3-pyridyl);

Bicyclo[2.2.1 ]hepta-2,5-diene-2-(2-pyridyl),3-(2-pyridyl);

Bicyclo[2.2.1 ]hepta-2,5-diene-2-(carboxy),3-(2-methylphenyl);

Bicyclo[2.2.1 ]hepta-2,5-diene-2-(carboxy),3-(2-methoxyphenyl);

Bicyclo[2.2.1 ]hepta-2,5-diene-2-(carboxy),3-(2-chlorophenyl);

Bicyclo[2.2.1 ]hepta-2,5-diene-2-(carboxy),3-(2-nitrophenyl).

Bicyclo[2.2.1 ]hepta-2,5-diene-2-(4-pyridyl),3-(4-methylphenyl),

Bicyclo[2.2.1 ]hepta-2,5-diene-2-(4-pyridyl),3-(4-methoxyphenyl),

Bicyclo[2.2.1 ]hepta-2,5-diene-2-(4-pyridyl),3-(4-dimethylaminphenyl), Bicyclo[2.2.1 ]hepta-2,5-diene-2-(4-pyridyl),3-(4-diethylaminphenyl), bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(2-chlorophenyl);

bicyclo[2.2.1 ]hepta-2,5-diene-2-carboxylic acid, 3-(2-methoxyphenyl)-;

bicyclo[2.2.1 ]hepta-2,5-diene-2-carboxylic acid, 3-(2-nitrophenyl)-;

bicyclo[2.2.1]hepta-2,5-diene-2-(2-chlorophenyl), 3-(2-chlorophenyl);

bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(2-thiophene); bicyclo[2.2.1 ]hepta-2,5-diene-2-(4-cyanophenyl), 3-(2-thiophene).

An embodiment of the invention is the compound according to Formula I wherein R ¹ represents substituent selected from the group consisting of substituted phenyl, naphthyl, substituted naphthyl, heteroaryl, and substituted heteroaryl; wherein the substituted phenyl, substituted naphthyl, and substituted heteroaryl, are substituted at least in one of its ortho-positions with one or more substituents selected from the group of CN, C(Hal)3, R ³ , OR ³ ,

Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ ), or

R ¹ represents substituent selected from the group consisting of substituted naphthyl, and substituted heteroaryl, which is substituted at least in one of its ortho-positions with substituents forming steric bulk;

R ² represents aryl, substituted aryl, heteroaryl, and substituted heteroaryl, (which substituted aryl and substituted heteroaryl groups are substituted with one or more substituents selected from the group consisting of, CN, C(Hal)3, R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) _2J NH(R ³ )); CN; CO; COOR ⁴ ; COR ⁴ ; CON(R ⁴ ) ₂ ;

C = C(CN) _2;

R ³ independently represents C1-C10 alkyl, optionally substituted with Hal;

R ⁴ independently represents H, C1-C10 alkyl, optionally substituted with Hal; with the proviso that the compound is not one of the disclaimed above.

Another embodiment defines the compounds of Formula I wherein R ¹ is defined above,

R ³ independently represents C1-C10 alkyl; R ² represents cyano (-CN); CO; COOR ⁴ ; COR ⁴ ; CON(R ⁴ ) ₂ ; C=C(CN) ₂ wherein R ⁴ independently represents H, linear or branched C1-C10 alkyl or fluorinated variations. R ² may also represent C(Hal) ₃ , R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ ).

Another embodiment defines the compounds of Formula I wherein R ¹ represents substituted phenyl, naphthyl, substituted naphthyl, heteroaryl, and substituted heteroaryl; wherein phenyl; naphthyl; heteroaryl, when substituted is substituted in its ortho-position; and is substituted with one or more substituents selected from the group of CN, C(Hal)3, R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ ), or R ¹ represents substituent selected from the group consisting of substituted naphthyl, and substituted heteroaryl, which is substituted at least in one of its ortho-positions with substituents forming steric bulk.

R ³ independently represents C1-C10 alkyl.

Preferably, the phenyl, naphthyl and heteroaryl is substituted in its ortho- position.

Another embodiment of the invention is a compound according to Formula I wherein R ¹ represents substituted phenyl according to

Formula lla:

Formula lla;

Formula Mb wherein

R ^' represents R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ );

R ^" represents H, R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ );

R ^{1 i} , R ^{1 ii} , R ^{1 iii} independently represent: H, R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ ), aryl; 1 -naphthyl, optionally substituted with one or more of H, R ³ , OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ );

R ² represents aryl, substituted aryl, heteroaryl, and substituted heteroaryl, (which substituted aryl and substituted heteroaryl groups are substituted with one or more substituents selected from the group consisting of CN, C(Hal)3, R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ )); CN; CO; COOR ⁴ ; COR ⁴ ; CON(R ⁴ ) ₂ ; C=C(CN) ₂ wherein R ⁴ independently represents H, C1-C10 alkyl, which alkyl is optionally substituted with Hal; R ³ independently represents C1-C10 alkyl; with the proviso that the compound is not one of the following compounds: Bicyclo[2.2.1]hepta-2, 5-diene, 2,3-bis(2-methoxyphenyl)-;

Bicyclo[2.2.1]hepta-2, 5-diene, 2,3-bis(2-chlorophenyl)-;

Bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(1 -naphthalenyl)-, methyl ester;

Bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(2-chlorophenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(2-methoxyphenyl)-;

Bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(2-nitrophenyl)-;

Bicyclo[2.2.1]hepta-2,5-diene-2-(2-chlorophenyl), 3-(2-chlorophenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(2-methoxyphenyl); Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(2-chlorophenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-pyridyl),3-(4-pyridyl) ;

Bicyclo[2.2.1]hepta-2,5-diene-2-(3-pyridyl),3-(3-pyridyl) ;

Bicyclo[2.2.1]hepta-2,5-diene-2-(2-pyridyl),3-(2-pyridyl) ;

Bicyclo[2.2.1]hepta-2,5-diene-2-(carboxy),3-(2-methyl phenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(carboxy),3-(2-methoxyphe nyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(carboxy),3-(2-chlorophen yl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(carboxy),3-(2-nitropheny l).

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-pyridyl),3-(4-methyl phenyl),

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-pyridyl),3-(4-methoxyp henyl),

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-pyridyl),3-(4-dimethyl aminphenyl), Bicyclo[2.2.1]hepta-2,5-diene-2-(4-pyridyl),3-(4-diethylamin phenyl), bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(2-chlorophenyl);

bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(2-methoxyphenyl)-;

bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(2-nitrophenyl)-;

bicyclo[2.2.1]hepta-2,5-diene-2-(2-chlorophenyl), 3-(2-chlorophenyl);

bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(2-thiophene);

bicyclo[2.2.1]hepta-2,5-diene-2-(4-cyanophenyl), 3-(2-thiophene).

A further embodiment is a compound according to Formula I wherein R ¹ represents substituted phenyl according to Formula lla, wherein

R ^' represents OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ), N02;

R ^" represents H;

R ¹ⁱ , R ^{1 ii} , R ¹ⁱⁱⁱ independently represent: H, R ³ , OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ), 0(CH ₂ CH ₂ 0) _I-5 H;

wherein R ³ independently represents C1-C10 alkyl; and

R ² represents CN.

Another embodiment is a compound according to Formula I wherein R ¹ represents phenyl according to Formula lla; wherein R ^' represents R ³ , F, nitro (N0 ₂ ), -0(CI-IO alkyl), 0(CH ₂ CH ₂ 0)i _-5 H or -N(Ci-io alkyl);

or wherein R ¹ represents phenyl according to Formula lla; and

R ^' represents OCH3; and R , R ¹ⁱ , R ^{1 ii} , R ^{1 iii} represent hydrogen (H); or wherein R ¹ represents phenyl according to Formula II; R ^' , R ¹ⁱⁱ represent OCH3; and R ^" , R ¹ⁱ , R ¹ⁱⁱⁱ represent hydrogen (H).

Another embodiment is a compound according to Formula I wherein R ¹ represents 1 -naphthyl,

optionally substituted with R ³ , F, N0 ₂ , 0(Ci-io alkyl), or N(Ci-io alkyl), or 0(CH ₂ CH ₂ 0) _I-5 H; or wherein R ¹ represents 2-thiophene, or 3-thiophene, optionally substituted with R ³ , F, N0 ₂ , 0(Ci-io alkyl), or -N(Ci-io alkyl), 0(CH ₂ CH ₂ 0) _I-5 H.

An embodiment of the invention is the quadricyclane (QC) compound corresponding to the norbornadiene compound as defined above. The compound is of Formula III:

Formula III

wherein R ¹ represents a substituents selected from the group consisting of substituted phenyl, naphthyl, substituted naphthyl, heteroaryl, and substituted heteroaryl; wherein the substituted phenyl, substituted naphthyl, and substituted heteroaryl, are substituted at least in one of its ortho-positions; and are substituted with one or more substituents selected from the group of CN, C(Hal) ₃ , R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ ), or

R ¹ represents substituent selected from the group consisting of substituted naphthyl, and substituted heteroaryl, which is substituted at least in one of its ortho-positions with substituents forming steric bulk;

R ² represents aryl, substituted aryl, heteroaryl, and substituted heteroaryl, (which substituted aryl and substituted heteroaryl groups are substituted with one or more substituents selected from the group consisting of, CN, C(Hal)3, R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) _2J NH(R ³ )); CN; CO; COOR ⁴ ; COR ⁴ ; CON(R ⁴ ) ₂ ;

C = C(CN) _2;

R ³ independently represents C1-C10 alkyl, optionally substituted with Hal;

R ⁴ independently represents H, C1-C10 alkyl, optionally substituted with Hal; with the proviso that the compound is not the corresponding photoisomer to: Bicyclo[2.2.1 ]hepta-2, 5-diene, 2,3-bis(2-methoxyphenyl)-;

Bicyclo[2.2.1 ]hepta-2, 5-diene, 2,3-bis(2-chlorophenyl)-;

Bicyclo[2.2.1 ]hepta-2,5-diene-2-carboxylic acid, 3-(1 -naphthalenyl)-, methyl ester;

Bicyclo[2.2.1 ]hepta-2,5-diene-2-carboxylic acid, 3-(2-chlorophenyl);

Bicyclo[2.2.1 ]hepta-2,5-diene-2-carboxylic acid, 3-(2-methoxyphenyl)-;

Bicyclo[2.2.1 ]hepta-2,5-diene-2-carboxylic acid, 3-(2-nitrophenyl)-;

bicyclo[2.2.1 ]hepta-2,5-diene-2-(2-chlorophenyl), 3-(2-chlorophenyl);

bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(2-methoxyphenyl); bicyclo[2.2.1 ]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(2-chlorophenyl);

bicyclo[2.2.1 ]hepta-2,5-diene-2-(4-pyridyl),3-(4-pyridyl);

bicyclo[2.2.1 ]hepta-2,5-diene-2-(3-pyridyl),3-(3-pyridyl);

bicyclo[2.2.1 ]hepta-2,5-diene-2-(2-pyridyl),3-(2-pyridyl);

bicyclo[2.2.1 ]hepta-2,5-diene-2-(carboxy),3-(2-methyl phenyl);

bicyclo[2.2.1 ]hepta-2,5-diene-2-(carboxy),3-(2-methoxyphenyl);

bicyclo[2.2.1 ]hepta-2,5-diene-2-(carboxy),3-(2-chlorophenyl); bicyclo[2.2.1 ]hepta-2,5-diene-2-(carboxy),3-(2-nitrophenyl).

bicyclo[2.2.1 ]hepta-2,5-diene-2-(4-pyridyl),3-(4-methyl phenyl),

bicydo[2.2.1 ]hepta-2,5-diene-2-(4-pyridyl),3-(4-methoxyphenyl),

bicydo[2.2.1]hepta-2,5-diene-2-(4-pyridyl),3-(4-dimethyla nninphenyl), bicydo[2.2.1 ]hepta-2,5-diene-2-(4-pyridyl),3-(4-diethylanninphenyl), bicydo[2.2.1]hepta-2,5-diene-2-carboxylic add, 3-(2-chlorophenyl);

bicydo[2.2.1 ]hepta-2,5-diene-2-carboxylic add, 3-(2-methoxyphenyl)-;

bicydo[2.2.1 ]hepta-2,5-diene-2-carboxylic add, 3-(2-nitrophenyl)-;

bicydo[2.2.1]hepta-2,5-diene-2-(2-chlorophenyl), 3-(2-chlorophenyl);

bicydo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(2-thiophene);

bicydo[2.2.1 ]hepta-2,5-diene-2-(4-cyanophenyl), 3-(2-thiophene).

Another embodiment of the invention is the compound of Formula III with R1 , R2, R3, and R4 as defined herein.

An embodiment of the invention is the compound of Formula III obtainable by a process wherein the compound of Formula I as defined in any of claims 1 to 10, optionally, is placed in a solvent; and is exposed to light of wavelength in the range of 150 nm to 900 nm.

An embodiment of the invention is the quadricyclane (QC) compound corresponding to the norbornadiene compound as defined above.

Another embodiment of the invention is a compound according to Formula III wherein R ¹ represents substituted phenyl according to

Formula lla:

Formula lla or Formula Mb

Formula Mb;

wherein

R ^' represents R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ );

R ^" represents H, R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ );

R ¹ⁱ , R ^{1 ii} , R ¹ⁱⁱⁱ independently represent: H, R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ ), aryl; 1 -naphthyl, optionally substituted with one or more of H, R ³ , OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ); R ³ represents linear or branched C1-C10 alkyl; and

R ² represents aryl, substituted aryl, heteroaryl, and substituted heteroaryl, (which aryl and heteroaryl groups are substituted with one or more

substituents selected from the group consisting of CN, C(Hal)3, R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ )); CN; CO; COOR ⁴ ; COR ⁴ ; CON(R ⁴ ) ₂ ; C=C(CN) ₂ wherein R ⁴ independently represents H, C1-C10 alkyl, which alkyl is optionally substituted with Hal;

with the proviso that the compound is not one of them disclaimed

corresponding QC of the following NDB compounds as in claim 1.

In one embodiment, the compound of Formula I is one or more from the following

3-(4-Nitrophenyl)bicyclo[2.2.1]hepta-2,5-diene-2-carbonitril e (2a);

3-(3-Nitrophenyl)bicyclo[2.2.1]hepta-2,5-diene-2-carbonit rile (2b);

3-(4-Fluorophenyl)bicyclo[2.2.1]hepta-2,5.diene-2-carboni trile (2c);

3-(2-Fluorophenyl)bicyclo[2.2.1]hepta-2,5.diene-2-carboni trile (2d);

3-(3-Fluoro-4-methoxyphenyl)bicyclo[2.2.1]hepta-2,5-diene -2-carbonitrile (2 e);

3-(2-Methoxyphenyl)bicyclo[2.2.1]hepta-2,5-diene-2-carbon itrile (2f);

3-(3-Methoxyphenyl)bicyclo[2.2.1]hepta-2,5-diene-2-carbon itrile (2g);

3-(3,4-Dimethoxyphenyl)bicyclo[2.2.1]hepta-2,5-diene-2-ca rbonitrile (2h); 3-(2,4-Dimethoxyphenyl)bicyclo[2.2.1]hepta-2,5-diene-2-carbo nitrile (2i); 3-(3,4,5-Trimethoxyphenyl)bicyclo[2.2.1]hepta-2,5-diene-2-ca rbonitrile (2j); 3-(Benzo[c/][1 ,3]dioxol-5-yl)bicyclo[2.2.1]hepta-2,5-diene-2-carbonitnle (2k); 3-(Naphthalen-1 -yl)bicyclo[2.2.1]hepta-2,5-diene-2-carbonitrile (2I);

3-(Naphthalen-2-yl)bicyclo[2.2.1]hepta-2,5-diene-2-carbon itrile (2m);

3-(4-(Dimethylamino)phenyl)bicyclo[2.2.1]hepta-2,5-diene- 2-carbonitrile (2n); 3-(4-(te/t-Butylthio)phenyl)bicyclo[2.2.1]hepta-2,5-diene-2- carbonitrile (2o); 3-(Thiophen-2-yl)bicyclo[2.2.1]hepta-2,5-diene-2-carbonitril e (2p); and 3-(Thiophen-2-yl)bicyclo[2.2.1]hepta-2,5-diene-2-carbonitril e (2q).

In another embodiment the compound of Formula I provided is one or more from the following

3-(2-Fluorophenyl)bicyclo[2.2.1]hepta-2,5.diene-2-carbonitri le (2d);

3-(2-Methoxyphenyl)bicyclo[2.2.1]hepta-2,5-diene-2-carbon itrile (2f);

3-(2,4-Dimethoxyphenyl)bicyclo[2.2.1]hepta-2,5-diene-2-ca rbonitrile (2i); and 3-(Naphthalen-1 -yl)bicyclo[2.2.1]hepta-2,5-diene-2-carbonitrile (2I).

In one embodiment, the compound of Formula III provided is one or more from the following:

2-Cyano-3-(4-nitrophenyl)quadricyclane (7a);

2-Cyano-3-(3-nitrophenyl)quadricyclane (7b);

2-Cyano-3-(4-fluorophenyl)quadricyclane (7c);

2-Cyano-3-(2-fluorophenyl)quadricyclane (7d);

2-Cyano-3-(3-fluoro-4-methoxyphenyl)quadricyclane (7e);

2-Cyano-3-(2-methoxyphenyl)quadricyclane (7f);

2-Cyano-3-(3-methoxyphenyl)quadricyclane (7g);

2-Cyano-3-(3,4-dimethoxyphenyl)quadricyclane (7h);

2-Cyano-3-(2,4-dimethoxyphenyl)quadricyclane (7i);

2-Cyano-3-(3,4,5-trimethoxyphenyl)quadricyclane (7j);

2-Cyano-3-(3,4-methylenedioxyphenyl)quadricyclane (7k);

2-Cyano-3-(1 -naphthyl)quadricyclane (7I);

2-Cyano-3-(2-naphthyl)quadricyclane (7m);

2-Cyano-3-(4-(A/,/V-dimethylamino)phenyl)quadricyclane (7n);

2-Cyano-3-(4-(te/t-butylthio)phenyl)quadricyclane (7o);

2-Cyano-3-(2-thiophenyl)quadricyclane (7p); and

2-Cyano-3-(3-thiophenyl)quadricyclane (7q). Another embodiment the compound of Formula III is one or more from the following

2-Cyano-3-(2-fluorophenyl)quadricyclane (7d);

2-Cyano-3-(2-methoxyphenyl)quadricyclane (7f);

2-Cyano-3-(2,4-dimethoxyphenyl)quadricyclane (7i); and

2-Cyano-3-(1 -naphthyl)quadricyclane (7I).

In another embodiment the QC compound is the compound according to Formula III obtainable by a process wherein the compound of Formula I as defined in claim 1 , is exposed with light of a wavelength in the range of 150 to 900, such as between 150 nm and 500 nm, for example with a wavelength of 310 nm, or 365nm.

The energy reaction, i.e. the conversion QC to NBD, can take place in water, or it can be solvent free, thus where the compounds of the invention is in liquid form. If solvent is present, it shall be optically transparent. Examples of suitable solvents are water, chloroform, toluene, benzyl alcohol, mineral oil, synthetic oils, silicone oils, ethylene glycol, polyethyleneglycols, water.

The compounds of Formula I and III have shown to fulfil requirements like solar spectrum match for the absorption of the parent compound; have a high photoisomerization quantum yield; have minimal spectral overlap between the parent compound and the photoisomer, and have a highly endergonic reaction profile with a high activation energy for the reverse reaction (from QC to NBD). Further, it has been shown that the compounds herein defined provides a surprisingly advantageously combination of solar spectrum match and long-term energy storage. The compounds exhibit long half-lives for their metastable forms without significantly affecting the other properties, especially the solar spectrum match and the energy storage density.

Further, an embodiment of the invention is the process for synthesizing the compound of Formula I wherein the compounds are synthesized according the following scheme showing Method A (herein shown with R ² =CN and R ¹ =aryl (AR)): Method A

or according to Method B (herein shown with R ² =CN and R ¹ =aryl (AR)):

Method B

Method A includes three alternative steps; a) POCI3, DMF, 50 °C; b) b, NFbaq, CHCI3; or c) NaOH, H ₂ O, THF. Step d) is performed with chlorobenzene, butylatedhydroxytoluene (BFIT), and heat. Method B is either e) ArB(OFI) ₂ , CsF, cat. Pd2dba3/PtBu3, TFIF; or f) ArB(OFI)2, K2CO3, cat. Pd(OAc)2/RuPhos, toluene/FhO.

Another embodiment of the invention is the use of the compound according to Formula I as defined herein for solar energy storage and/or solar energy conversion.

Another embodiment of the invention is an energy storage device comprising a molecular solar thermal system, or a solar thermal fuel system, comprising the compound according to Formula I, or a mixture of two or more

compounds according to Formula I. In one embodiment the compound, or mixture of two or more, according to Formula I is present in form of a liquid. In this case, a functional device may consist of a solar collector part, a storage compartment and an energy extraction device that triggers the MOST system to release the stored energy and recover the original NBD molecule. Further, the energy storage device may be a device in form of a functional material for thermal management. It can be selected from functional coating, or functional fabrics. In one embodiment the energy storage device is a polymer film comprising the MOST molecules blended therein. The compounds of Formula I may be included in solar energy devices, like a solar energy collector. An example of a solar energy collector comprises

-a wavelength converter;

-an energy converter being a molecular solar thermal system; wherein the molecular solar thermal system comprises one or more compounds according to Formula I, without the provisos, as defined herein.

In another embodiment of the invention the molecular structures Formula I and III are part of an oligomer or polymer chain, containing 2 or more NBD subunits. The compound of Formula I and III can either be part of the back- bone or grafted onto the polymer as pendant side chains.

In an embodiment of the invention, a method of storing energy is defined. The method comprises the following steps:

i) providing an energy storage device comprising a molecular solar thermal system (MOST) including one or more compounds according to Formula I;

ii) illuminating the solar thermal fuel thereby converting the one or more compounds of Formula I from a lower-energy state to a higher-energy metastable state of corresponding Formula III;

iii) storing the one or more compound of Formula III in the higher- energy metastable state for a period of time 0.1 to 7000 days; and iv) providing a trigger to cause the compound of Formula III to revert to lower-energy state. DEFINITIONS

In connection with the compounds herein defined some terms require to be defined. By the term“heteroaryl” it is herein meant a five- to twelve - membered heterocyclic aromatic system containing one or more heteroatoms selected from oxygen, nitrogen and/or sulfur, which groups are optionally substituted by one or more substituents selected from CN, C(Hal)3, R ³ , OR ³ , Hal, NO2, N(R ³ ) ₂ , NH(R ³ ). Examples of heteroaryls are thiophene, like 2- thiophene, and 3-thiophene, pyrrole, pyrrolidone, furan, benzofuran, indoles, benzothiophenes, quinolones, naphthofurans, dibenzofurans, benzothiazoles, benzoxazoles, azaquinolines, oxazoles, thiazoles, like 1 ,4-thiazole, and 1 ,5- thiazole, diazines, thiazines, naphthoxazoles, benzodifurans and the oxygen, nitrogen and sulfur analogues and combination of two of these three heteroatoms in the ring system.

The term“aryl”, when used herein, includes C6-20 aryl groups, such as phenyl, naphthyl and the like. Unless specified aryl may be substituted by one or more substituents including CN, C(Hal)3, R ³ , OR ³ , Hal, NO2, N(R ³ )2, NH(R ³ ), or substituents forming steric bulk. Examples of aryls are phenyl, 1 -naphthyl, 2-naphthyl, biphenyl, as well as bicyclic and tricyclic variants. When defining aryl being substituted in ortho-position, herein this is meant also to include the 1 -naphthyl.

The term“substituents forming steric bulk” when used herein it is meant substituents forming a bulky structure by binding to one or more atoms in the naphtyl or heteroaryl. Examples are phenyl, naphtyl, and heteroaryl being substituted in its ortho- positions with substituents as defined herein (R ¹ ). Other examples are naphtyl and heteroaryl having hydrogen substituted in 1 - position, or 1 -napthyl, and 2-naphtyl substituted in similar way.

Unless otherwise specified,‘alkyl’ groups and‘alkoxy’ groups as defined herein may be straight-chain, or when there is a sufficient number (i.e. a minimum of three) of carbon atoms be branched-chain, and/or cyclic. Further, when there is a sufficient number (i.e. a minimum of four) of carbon atoms, such alkyl and alkoxy groups may also be part cyclic/acyclic. Such alkyl and alkoxy groups may also be saturated or, when there is a sufficient number (i.e. a minimum of two) of carbon atoms, be saturated and/or interrupted by one or more oxygen and/or sulfur atoms. Examples of alkyl groups are Ci-s alkyl, Ci-3 alkyl, and more specifically methyl, ethyl, propyl, butyl, and pentyl. Examples of alkyl groups are Ci-s alkoxy, Ci-3 alkoxy, and more specifically methoxy, ethoxy, propoxy, butoxy, and pentoxy.

Unless otherwise specified, alkyl and alkoxy groups may also be substituted by one or more Hal, and especially fluoro. Examples are Ci-3 alkyl substituted with one or more F, such as CF3.

The term“halogen”,“halo”, or“Hal”, when used herein includes fluoro (F), chloro (Cl), bromo (Br), and iodo (I). Unless otherwise specified, Formula I and III is substituted by substituents selected from H, Ci-6 alkyl, Hal, aryl.

BRIEF DESCRIPTION OF THE DRAWINGS FIG 1 shows the energy landscape of the conversion of parent to

photoisomer, including the activation barrier E _a for back conversion from photoisomer to parent molecule.

DETAILED DESCRIPTION

The invention herein described relates to molecular solar thermal system (MOST), and the conversion between the norbornadiene compound according to Formula I and the corresponding quadricyclane (QC) compound according to the compound of Formula III, as shown by the following reaction scheme:

Formula I Formula III

Essential to the function of any MOST system is the thermal stability of the photoisomer as controlled by the barrier height (see fig. 1 ). For the NBD - QC it has until now been a major challenge to retain a high barrier for back reaction, while at the same time establishing molecules with good solar spectrum match and high energy density.

By the compounds herein defined it is discovered that it is possible to delineate these properties. Especially, by introducing substituents in the ortho position of 2,3-aryl substituted norbornadienes, or substituents in the ortho position of the aryl or heteroaryl substituted in one or both of the positions of 2,3-substituted norbornadienes, or other bulky groups in the same positions such as e.g. fused benzene rings, such as naphtalene attached in the 1 or 2 position to the norbornadiene. These compounds do all demonstrate an increase in the storage lifetime (ti _/ 2) as compared to their non ortho

substituted analogues.

All compounds are thoroughly characterized, including energy storage density measured by differential scanning calorimetry (DSC), mapping of the activation barriers via Eyring plots and measuring of quantum yields. All substances shown by the Examples below shows good effect, but is even more indicated that the influence of ortho substitution on the reaction barrier height is rationalized using quantum chemical models. Further, the solar spectrum match, or the absorption spectrum, of the compounds of the invention have been shown to be extraordinary. The compounds herein described do exhibit these properties which can be utilised dependency of each other, or alternatively, independently. Therefore, the compounds can be utilised in a broad range of applications.

The compounds according to Formula I may be synthesised by for example, method A, another option is according to method B, but further methods are also available. For example, according to method A (shown with R1 = aryl, and R2=CN) ,

Method A

the acetylenic precursors 5 could be prepared on large scale using the previously reported procedure from the corresponding substituted

acetophenones 4 (Scheme 1 , with a) POCI3, DMF, 50 °C; b) b, NFbaq, CFICI3; c) NaOFI, FI2O, TFIF; d) chlorobenzene, butylatedhydroxytoluene (BFIT), heat). ^A These precursors had both electron withdrawing and donating substituents on a benzene ring, in addition to multiple substituent patterns, and polycyclic structures. Diels-Alder reactions (Method A) with

cyclopentadiene generally went in good yield, using microwave irradiation in temperatures ranging from 100 to 130 °C (see Examples) to afford a host of NBD derivatives. Generally, the compounds are conveniently purified directly from the reaction vial by flash chromatography. In many instances a lot of these reactions were accompanied by recovery of starting materials, which could in any case be recycled back into successive reactions.

For some of the ortho-methoxy substituted compounds according to Formula I Method B (shown with R1 =aryl (Ar), and R2=CN), the Suzuki reaction,

Method B

is a more advantagous choise of synthesising. In method B, the 6 is reacted with ortho-methoxyphenylboronic acid. Palladium catalysis was also employed for the synthesis of NBDs 2i and 3-substituted thiophene derivative 2q in order to compliment this study.

The compound according to Formula I as is described above include following substituents:

R ¹ represents substituent according to Formula lla, wherein R ^' represents OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ), N0 ₂ ;

R ^" represents H;

R ¹ⁱ , R ^{1 ii} , R ¹ⁱⁱⁱ independently represent H, OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ );

wherein R ³ independently represents C1 -C5 alkyl; and

R ² represents aryl, substituted aryl, heteroaryl, and substituted heteroaryl, (which aryl and heteroaryl groups are substituted with one or more substituents selected from the group consisting of CN, C(Hal)3, R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ )); CN; CO; COOR ⁴ ; COR ⁴ ; CON(R ⁴ ) ₂ ; C=C(CN) ₂ wherein Hal is selected from F and Cl;

R ³ independently represents C ₁ -C ₅ alkyl;

R ⁴ independently represents H, C1 -C5 alkyl, optionally substituted with Hal. Further the compound is defined with the following,

R ¹ represents substituent according to Formula lla, wherein

R ^' represents OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ), N0 ₂ ;

R ^" represents H;

R ^{1 i} , R ^{1 ii} , R ^{1 iii} independently represent H, OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ );

wherein R ³ independently represents C1-C3 alkyl; and

R ² represents phenyl, substituted phenyl, heteroaryl, and substituted heteroaryl, (which phenyl and heteroaryl groups are substituted with one or more substituents selected from the group consisting of CN, C(Hal)3, R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) _2J NH(R ³ )); CN; COOR ⁴ ;

R ³ independently represents C ₁ -C3 alkyl;

R ⁴ independently represents H, C1 -C5 alkyl, optionally substituted with Hal;

Hal is selected from F and Cl.

In a further aspect of the invention, the R ¹ represents substituent according to Formula Mb, substituted with one or more of H, OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ),

N0 ₂ ;

R ² represents phenyl, substituted phenyl, heteroaryl, and substituted heteroaryl, (which phenyl and heteroaryl groups are substituted with one or more substituents selected from the group consisting of CN, C(Hal)3, R ³ , OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ )); CN; COOR ⁴ ;

R ³ independently represents C ₁ -C ₅ alkyl;

R ⁴ independently represents H, C1 -C5 alkyl, optionally substituted with Hal; and

Hal is selected from F and Cl.

In a further aspect of the invention, R ¹ represents substituent according to Formula Mb, substituted with one or more of H, OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ),

N0 ₂ ; R ² represents phenyl, substituted phenyl, heteroaryl, and substituted heteroaryl, (which phenyl and heteroaryl groups are substituted with one or more substituents selected from the group consisting of CN, C(Hal)3, R ³ , OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ )); CN; COOR ⁴ ;

R ³ independently represents C ₁ -C ₅ alkyl;

R ⁴ independently represents H, C1 -C5 alkyl, optionally substituted with Hal; and

Hal is selected from F.

In a further aspect of the invention, R ¹ represents substituent according to Formula lla, wherein

R ^' represents OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ), N0 ₂ ;

R ^" represents H;

R ¹ⁱ , R ^{1 ii} , R ¹ⁱⁱⁱ independently represent H, OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ );

wherein R ³ independently represents C1 -C5 alkyl; and

R ² represents CN.

In a further aspect of the invention, R ¹ represents substituent according to Formula lla, wherein

R ^' represents OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ), N0 ₂ ;

R ^" represents H;

R ¹ⁱ , R ^{1 ii} , R ¹ⁱⁱⁱ independently represent H, OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ );

wherein R ³ independently represents C1 -C5 alkyl; and

R ² represents COOH.

In a further aspect of the invention, R ¹ represents substituent according to Formula lla, wherein

R ^' represents OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ), N0 ₂ ;

R ^" represents H;

R ¹ⁱ , R ^{1 ii} , R ¹ⁱⁱⁱ independently represent H, OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ );

wherein R ³ independently represents C1 -C5 alkyl; and

R ² represents phenyl, optionally substituted with OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ), N0 ₂ ;

Hal represents F or Cl. In a further aspect of the invention, R ¹ represents phenyl according to

Formula lla; wherein R ^' represents R ³ , F, NO2, 0(Ci-io alkyl), or -N(Ci-io alkyl).

In a further aspect of the invention, R ¹ represents phenyl according to

Formula lla; wherein

R ^' represents R ³ , F, NO2, 0(Ci-5 alkyl), or -N(CI-5 alkyl).

In a further aspect of the invention, R ¹ represents phenyl according to

Formula lla; and

R ^' represents OCFI3; and

R , R ^{1 i} , R ^{1 ii} , R ^{1 iii} represent hydrogen (FI).

In a further aspect of the invention, R ¹ represents substituent according to Formula lla;

R ^' , R ^{1 ii} represent OCFI3; and

R , R ^{1 i} , R ^{1 iii} represent hydrogen (FI).

In a further aspect of the invention, R ¹ represents 1 -naphtyl or 2-naphthyl, optionally substituted with R ³ , F, NO2, 0(Ci-io alkyl), or -N(Ci-io alkyl).

R ² represents CN; COOR ⁴ ; CONR ⁴ ; or COC(R ⁴ ) ₃ .

In a further aspect of the invention, R ¹ represents 2-thiophene, or 3- thiophene, optionally substituted with R ³ , F, NO2, 0(Ci-s alkyl), or -N(CI-5 alkyl); and R ² represents CN; COOR ⁴ ; COR ⁴ , or CONR ⁴ .

In a further aspect of the invention, R ¹ represents 1 ,4-triazole, or 1 ,5 triazole, optionally substituted with R ³ , F, NO2, 0(Ci-s alkyl), or -N(CI-5 alkyl).

R ² represents CN; COOR ⁴ ; CONR ⁴ ; or COC(R ⁴ ) ₃

The compound included herein is according to Formula I wherein R ¹ represents aryl, substituted aryl, heteroaryl, and substituted heteroaryl, which groups are substituted with one or more substituents selected from the group consisting of CN, C(FHal)3, R ³ , OR ³ , FHal, NO2, N(R ³ )2, NFI(R ³ ), or substituents forming steric bulc;

with the proviso that when aryl is phenyl, the phenyl is substituted;

R ² represents aryl, substituted aryl, heteroaryl, and substituted heteroaryl, (which aryl and heteroaryl groups are substituted with one or more

substituents selected from the group consisting of CN, C(FHal)3, R ³ , OR ³ , FHal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ )); CN; CO; COOR ⁴ ; COR ⁴ ; CON(R ⁴ ) ₂ ; C=C(CN) _2; C(Hal) ₃ , R ³ , OR ³ , Hal, NO2, N(R ³ ) ₂ , NH(R ³ ). _; wherein R ⁴ independently represents H, C1-C10 alkyl, optionally substituted with Hal;

R ³ independently represents C1-C10 alkyl;

R ² may also represent C(Hal) ₃ , R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ ).

Preferably, the substituted aryl and substituted heteroaryl are substituted in its ortho-position. Further, the compounds are as above with the proviso that it is not any of the following compounds:

Bicyclo[2.2.1]hepta-2, 5-diene, 2,3-bis(2-methoxyphenyl)-;

Bicyclo[2.2.1]hepta-2, 5-diene, 2,3-bis(2-chlorophenyl)-;

Bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(1 -naphthalenyl)-, methyl ester;

Bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(2-chlorophenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(2-methoxyphenyl)-;

Bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(2-nitrophenyl)-;

Bicyclo[2.2.1]hepta-2,5-diene-2-cyano, 3-phenyl;

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-cyanophenyl), 3-(4-methoxyphenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(phenyl), 3-(phenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(phenyl), 3-(4-methoxyphenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-trifluoromethylphenyl) , 3-(4- methoxyphenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-trifluoromethylphenyl), 3-(4-dimethylamin); Bicyclo[2.2.1]hepta-2,5-diene-2-(2-chlorophenyl), 3-(2-chlorophenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(4-cyanophenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(2-thiophene);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-cyanophenyl), 3-(2-thiophene).

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-ethylphenyl), 3-(4-ethylphenyl).

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-dimethylamin), 3-(4-dimethylamin).

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(4-methoxyphenyl), Bicyclo[2.2.1]hepta-2,5-diene-2-(3-methoxyphenyl), 3-(3-methoxyphenyl), Bicyclo[2.2.1]hepta-2,5-diene-2-(4-chlorophenyl), 3-(4-chlorophenyl),

Bicyclo[2.2.1]hepta-2,5-diene-2-(3-chlorophenyl), 3-(3-chlorophenyl),

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(4-ethylphenyl), Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(4-dimethylamin), Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(3-methoxyphenyl),

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(2-methoxyphenyl),

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(4-chlorophenyl),

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(3-chlorophenyl),

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(2-chlorophenyl),

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-pyridyl),3-(4-methyl phenyl),

Bicydo[2.2.1]hepta-2,5-diene-2-(4-pyridyl),3-(4-methoxypheny l),

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-pyridyl),3-(4-dinnethylan ninphenyl),

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-pyridyl),3-(4-diethyla nninphenyl),

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-pyridyl),3-(4-pyridyl),

Bicyclo[2.2.1]hepta-2,5-diene-2-(3-pyridyl),3-(3-pyridyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(2-pyridyl),3-(2-pyridyl),;

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-trifluoromethylphenyl),3- (4- methoxyphenyl),

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-trifluoromethylphenyl),3- (4- dimethylaminphenyl),

Bicyclo[2.2.1]hepta-2,5-diene-2-(carboxy),3-(4-methyl phenyl),

Bicyclo[2.2.1]hepta-2,5-diene-2-(carboxy),3-(2-methylphen yl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(carboxy),3-(4-methoxyphe nyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(carboxy),3-(4-methylphen yl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(carboxy),3-(2-methylphen yl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(carboxy),3-(4-methoxyphe nyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(2-thiophen); or Bicyclo[2.2.1]hepta-2,5-diene-2-(4-cyanophenyl), 3-(2-thiophen).

The compound of the invention is according to Formula I wherein R ¹ represents aryl, substituted aryl, heteroaryl, and substituted heteroaryl, which groups are substituted with one or more substituents selected from the group consisting of CN, C(Hal) ₃ , R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ );

with the proviso that when aryl is phenyl, the phenyl is substituted. Preferably R ¹ represents a substituent selected from substituted phenyl, naphthyl, substituted naphthyl, heteroaryl, and substituted heteroaryl; wherein phenyl; naphthyl; heteroaryl, when substituted are substituted with one or more substituents selected from the group consisting of CN, C(Hal)3, R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ ).

Further, the compound of formula I where R ¹ represents substituted phenyl, naphthyl, substituted naphthyl, heteroaryl, and substituted heteroaryl; wherein phenyl; naphthyl; heteroaryl, when substituted are substituted with one or more substituents selected from the group consisting of CN, C(Hal)3, R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ ).

Further, R ¹ may represent substituted phenyl according to

Formula lla:

Formula lla

Formula Mb;

Formula lla and Formula Mb are optionally, independently, substituted with CN, C(Hal) ₃ , R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ ).

R ^' represents OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ ); and

R ^" represents H, OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ ).

R ^{1 i} , R ^{1 ii} , R ^{1 iii} independently represent: H, OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ ).

Also, R ^{1 i} , R ^{1 ii} , R ^{1 iii} may represent aryl; 1 -naphthyl, optionally substituted with one or more of OR ³ , Hal, N(R ³ )2, NH(R ³ ); R ³ represents linear or branched Ci- C10 alkyl. In one embodiment, R ¹ of Formula I represents substituent according to Formula lla, wherein

R ^' represents R ³ , OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ), N0 ₂ ;

R ^" represents H;

R ¹ⁱ , R ^{1 ii} , R ¹ⁱⁱⁱ independently represent H, OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ );

wherein R ³ independently represents linear or branched C1 -C10 alkyl, for example C1 -C5 alkyl, like linear or branched, methyl, ethyl, propyl, butyl, and pentyl.

In one embodiment, R ¹ represents phenyl according to Formula lla; wherein R ^' represents R ³ , F, N0 ₂ , 0(Ci-io alkyl), or -N(Ci-io alkyl).

Further, the compound according to Formula I may include R ¹ representing phenyl according to Formula lla; wherein R ^' is selected from F, N0 ₂ , 0(Ci-io alkyl), or -N(Ci-io alkyl); alternatively,

R ¹ represents phenyl according to Formula II; and

R ^' represents OCH3; and

R ^” , R ¹ⁱ , R ¹ⁱⁱ , R ¹ⁱⁱⁱ represent hydrogen (H); alternatively,

R ¹ represents phenyl according to Formula II;

R ^' , R ¹ⁱⁱ represent OCH3; and

R , R ¹ⁱ , R ¹ⁱⁱⁱ represent hydrogen (H).

Further, the compound according to Formula I may include R ¹ representing

1 -naphthyl, optionally substituted with R ³ , OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ), N0 _2. Further, the compound according to Formula I may include R ¹ representing

2-thiophene, or 3-thiophene, optionally substituted with OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ), N0 ₂ .

The compound of Formula I includes substituent R ² representing aryl, substituted aryl, heteroaryl, and substituted heteroaryl, which groups are substituted with one or more substituents selected from the group consisting of CN, C(Hal) ₃ , R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ );

CN; CO; COOR ⁴ ; COR ⁴ ; COCF ₃ , CON(R ⁴ ) ₂ ; C=C(CN) ₂ wherein R ⁴ independently represents H, linear or branched C1-C10 alkyl, and fluorinated variations; preferably R ² represents aryl, substituted aryl, heteroaryl, and substituted heteroaryl, which groups are substituted with one or more substituents selected from the group consisting of CN, C(Hal)3, R ³ , OR ³ , Hal, NO2, N(R ³ ) _2J NH(R ³ ); CN; CO; COOR ⁴ ; COR ⁴ ; CON(R ⁴ ) ₂ ; C=C(CN) ₂ wherein R ⁴ independently represents H, linear or branched C1-C10 alkyl or fluorinated variations.

Further, the compound of Formula I includes R ¹ representing a substituent according to Formula lla, wherein

R ^' represents OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ), N0 ₂ ;

R ^" represents H;

R ¹ⁱ , R ^{1 ii} , R ¹ⁱⁱⁱ independently represent H, OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ );

wherein R ³ independently represents linear or branched C1-C10 alkyl; and R ² represents CN.

Further, the compound of Formula I includes R ² representing a substituent CN; CO; COOR ⁴ ; COR ⁴ ; CON(R ⁴ ) ₂ ; C=C(CN) ₂ wherein R ⁴ independently represents H, linear or branched C1 -C10 alkyl, such as C1 -C5 alkyl, or C1 -C3 alkyl or fluorinated variations.

The compound of Formula I includes compound where

R ¹ represents substituent according to Formula lla, wherein

R ^' represents OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ), N0 ₂ ;

R ^" represents H;

R ¹ⁱ , R ^{1 ii} , R ¹ⁱⁱⁱ independently represent H, OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ );

wherein R ³ independently represents C1 -C5 alkyl; and

R ² represents aryl, substituted aryl, heteroaryl, and substituted heteroaryl,

(which substituted aryl and substituted heteroaryl groups are substituted with one or more substituents selected from the group consisting of CN, C(Hal)3,

R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) _2J NH(R ³ )); CN; CO; COOR ⁴ ; COR ⁴ ; CON(R ⁴ ) ₂ ;

C=C(CN) ₂ wherein

Hal is selected from F and Cl

R ³ independently represents C ₁ -C ₅ alkyl;

R ⁴ independently represents H, C1 -C5 alkyl, optionally substituted with Hal. The compound of Formula I includes compound where

R ¹ represents substituent according to Formula lla, wherein

R ^' represents OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ), N0 ₂ ;

R ^" represents H;

R ¹ⁱ , R ^{1 ii} , R ¹ⁱⁱⁱ independently represent H, OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ); wherein R ³ independently represents C1-C3 alkyl; and

R ² represents phenyl, substituted phenyl, heteroaryl, and substituted heteroaryl, (which phenyl and heteroaryl groups are substituted with one or more substituents selected from the group consisting of CN, C(Hal)3, R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ )); CN; COOR ⁴ ;

R ³ independently represents C ₁ -C3 alkyl;

R ⁴ independently represents H, C1 -C5 alkyl, optionally substituted with Hal;

Hal is selected from F and Cl.

The compound of Formula I includes compounds where

R ¹ represents substituent according to Formula Mb, substituted with one or more of H, OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ), N0 ₂ ;

R ² represents phenyl, substituted phenyl, heteroaryl, and substituted heteroaryl, (which phenyl and heteroaryl groups are substituted with one or more substituents selected from the group consisting of CN, C(Hal)3, R ³ , OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ )); CN; COOR ⁴ ;

R ³ independently represents C ₁ -C ₅ alkyl;

R ⁴ independently represents H, C1 -C5 alkyl, optionally substituted with Hal; and

Hal is selected from F and Cl.

The compound of Formula I includes compound where

R ¹ represents substituent according to Formula Mb, substituted with one or more of H, OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ), N0 ₂ ;

R ² represents phenyl, substituted phenyl, heteroaryl, and substituted heteroaryl, (which phenyl and heteroaryl groups are substituted with one or more substituents selected from the group consisting of CN, C(Hal)3, R ³ , OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ )); CN; COOR ⁴ ;

R ³ independently represents C ₁ -C ₅ alkyl;

R ⁴ independently represents H, C1 -C5 alkyl, optionally substituted with Hal; and

Hal is selected from F.

The compound of Formula I includes compound where

R ¹ represents substituent according to Formula lla, wherein

R ^' represents OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ), N0 ₂ ; R ^" represents H;

R ¹ⁱ , R ^{1 ii} , R ¹ⁱⁱⁱ independently represent H, OR ³ , Hal, N(R ³ )2, NH(R ³ );

wherein R ³ independently represents C1 -C5 alkyl; and

R ² represents CN.

The compound of Formula I includes compound where

R ¹ represents substituent according to Formula lla, wherein

R ^' represents OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ), N0 ₂ ;

R ^" represents H;

R ¹ⁱ , R ^{1 ii} , R ¹ⁱⁱⁱ independently represent H, OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ );

wherein R ³ independently represents C1 -C5 alkyl; and

R ² represents COOH.

The compound of Formula I includes compound where

R ¹ represents substituent according to Formula lla, wherein

R ^' represents OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ), N0 ₂ ;

R ^" represents H;

R ¹ⁱ , R ^{1 ii} , R ¹ⁱⁱⁱ independently represent H, OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ );

wherein R ³ independently represents C1 -C5 alkyl; and

R ² represents phenyl, optionally substituted with OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ), N0 ₂ ;

Hal represents F or Cl.

The compound of Formula I includes compound wherein

R ¹ represents phenyl according to Formula lla; wherein

R ^' represents R ³ , F, N0 ₂ , 0(Ci- ₅ alkyl), or -N(C _I -5 alkyl).

The compound of Formula I includes compounds wherein R ¹ represents phenyl according to Formula lla; and

R ^' represents OCH3; and

R , R ¹ⁱ , R ¹ⁱⁱ , R ¹ⁱⁱⁱ represent hydrogen (H).

The compound of Formula I includes compound wherein

R ¹ represents phenyl according to Formula lla;

R ^' , R ¹ⁱⁱ represent OCH3; and

R , R ¹ⁱ , R ¹ⁱⁱⁱ represent hydrogen (H).

The compound of Formula I includes compound wherein R ¹ represents 1 -naphtyl or 2-naphthyl, optionally substituted with R ³ , F, NO2, 0(Ci-io alkyl), or -N(Ci-io alkyl); and

R ² represents CN; COOR ⁴ ; CONR ⁴ ; or COC(R ⁴ ) ₃ .

The compound of Formula I includes compound where

R ¹ represents 2-thiophene, or 3-thiophene, optionally substituted with R ³ , F,

NO2, 0(Ci _-5 alkyl), or -N(CI-5 alkyl); and

R ² represents CN; COOR ⁴ ; COR ⁴ , or CONR ⁴ .

The compound of Formula I includes compound where

R ¹ represents 1 ,4-triazole, or 1 ,5 triazole, optionally substituted with R ³ , F,

N0 ₂ , 0(Ci _-5 alkyl), or -N(CI _-5 alkyl);

R ² represents CN; COOR ⁴ ; CONR ⁴ ; or COC(R ⁴ ) ₃ .

Further, the compound of Formula I includes R ² representing CN.

Following compounds are previously known, and disclaimed the scope of compounds of the invention:

Bicyclo[2.2.1]hepta-2, 5-diene, 2,3-bis(2-methoxyphenyl)-;

Bicyclo[2.2.1]hepta-2, 5-diene, 2,3-bis(2-chlorophenyl)-;

Bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(1 -naphthalenyl)-, methyl ester;

Bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(2-chlorophenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(2-methoxyphenyl)-;

Bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(2-nitrophenyl)-;

Bicyclo[2.2.1]hepta-2,5-diene-2-cyano, 3-phenyl;

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-cyanophenyl), 3-(4-methoxyphenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(phenyl), 3-(phenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(phenyl), 3-(4-methoxyphenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-trifluoromethylphenyl) , 3-(4- methoxyphenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-trifluoromethylphenyl), 3-(4-dimethylamin); Bicyclo[2.2.1]hepta-2,5-diene-2-(2-chlorophenyl), 3-(2-chlorophenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(4-cyanophenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(2-thiophen);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-cyanophenyl), 3-(2-thiophen). An embodiment of the invention is the quadricyclane (QC) compound corresponding to the norbornadiene compound as defined above. The compound is of Formula III:

Formula III

wherein

R ¹ represents aryl, substituted aryl, heteroaryl, and substituted heteroaryl, which groups are substituted with one or more substituents selected from the group consisting of CN, C(Hal) ₃ , R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ );

with the proviso that when aryl is phenyl, the phenyl is substituted;

R ² represents aryl, substituted aryl, heteroaryl, and substituted heteroaryl, (which aryl and heteroaryl groups are substituted with one or more

substituents selected from the group consisting of CN, C(Hal)3, R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ )); CN; CO; COOR ⁴ ; COR ⁴ ; CON(R ⁴ ) ₂ ; C=C(CN) _2; wherein R ⁴ independently represents H, C1-C10 alkyl, optionally substituted with Hal;

R ³ independently represents C1-C10 alkyl; and

with the proviso that it the compound is not the corresponding QC of the following NBD compounds:

Bicyclo[2.2.1]hepta-2, 5-diene, 2,3-bis(2-methoxyphenyl)-;

Bicyclo[2.2.1]hepta-2, 5-diene, 2,3-bis(2-chlorophenyl)-;

Bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(1 -naphthalenyl)-, methyl ester;

Bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(2-chlorophenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(2-methoxyphenyl)-;

Bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(2-nitrophenyl)-;

Bicyclo[2.2.1]hepta-2,5-diene-2-cyano, 3-phenyl; Bicyclo[2.2.1]hepta-2,5-diene-2-(4-cyanophenyl), 3-(4-methoxyphenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(phenyl), 3-(phenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(phenyl), 3-(4-methoxyphenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-trifluoromethylphenyl) , 3-(4- methoxyphenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-trifluoromethylphenyl), 3-(4-dimethylamin); Bicyclo[2.2.1]hepta-2,5-diene-2-(2-chlorophenyl), 3-(2-chlorophenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(4-cyanophenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(2-thiophene);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-cyanophenyl), 3-(2-thiophene);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-ethylphenyl), 3-(4-ethylphenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-dimethylamin), 3-(4-dimethylamin);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(4-methoxyphenyl); Bicyclo[2.2.1]hepta-2,5-diene-2-(3-methoxyphenyl), 3-(3-methoxyphenyl); Bicyclo[2.2.1]hepta-2,5-diene-2-(4-chlorophenyl), 3-(4-chlorophenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(3-chlorophenyl), 3-(3-chlorophenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(4-ethylphenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(4-dimethylamin);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(3-methoxyphenyl), Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(2-methoxyphenyl); Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(4-chlorophenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(3-chlorophenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(2-chlorophenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-pyridyl),3-(4-methylph enyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-pyridyl),3-(4-methoxyp henyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-pyridyl),3-(4-dimethyl anninphenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-pyridyl),3-(4-diethyla nninphenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-pyridyl),3-(4-pyridyl) ;

Bicyclo[2.2.1]hepta-2,5-diene-2-(3-pyridyl),3-(3-pyridyl) ;

Bicyclo[2.2.1]hepta-2,5-diene-2-(2-pyridyl),3-(2-pyridyl) ;

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-trifluoromethylphenyl) ,3-(4- methoxyphenyl); Bicyclo[2.2.1 ]hepta-2,5-diene-2-(4-trifluoromethylphenyl),3-(4- dimethylaminphenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(carboxy),3-(4-methylphenyl) ;

Bicyclo[2.2.1]hepta-2,5-diene-2-(carboxy),3-(2-methylphenyl) ;

Bicyclo[2.2.1 ]hepta-2,5-diene-2-(carboxy),3-(4-methoxyphenyl);

Bicyclo[2.2.1 ]hepta-2,5-diene-2-(carboxy),3-(4-methylphenyl);

Bicyclo[2.2.1 ]hepta-2,5-diene-2-(carboxy),3-(2-methylphenyl);

Bicyclo[2.2.1 ]hepta-2,5-diene-2-(carboxy),3-(4-methoxyphenyl).

Another embodiment of the invention is a compound according to Formula Ml wherein R ¹ represents substituted phenyl according to

Formula lla:

Formula Mb

wherein

R ^' represents R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ );

R ^" represents H, R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ ); R ^{1 i} , R ^{1 ii} , R ^{1 iii} independently represent: H, R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ ), aryl; 1 -naphthyl, optionally substituted with one or more of H, R ³ , OR ³ , Hal, N(R ³ ) ₂ , NH(R ³ ); R ³ represents linear or branched C1-C10 alkyl; and

R ² represents aryl, substituted aryl, heteroaryl, and substituted heteroaryl, (which aryl and heteroaryl groups are substituted with one or more

substituents selected from the group consisting of CN, C(Hal)3, R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) _2J NH(R ³ )); CN; CO; COOR ⁴ ; COR ⁴ ; CON(R ⁴ ) ₂ ; C=C(CN) ₂ wherein R ⁴ independently represents H, C1-C10 alkyl, which alkyl is optionally substituted with Hal;

with the proviso that the compound is not a corresponding QC of the following NDB compounds:

Bicyclo[2.2.1 ]hepta-2, 5-diene, 2,3-bis(2-methoxyphenyl)-;

Bicyclo[2.2.1 ]hepta-2, 5-diene, 2,3-bis(2-chlorophenyl)-;

Bicyclo[2.2.1 ]hepta-2,5-diene-2-carboxylic acid, 3-(1 -naphthalenyl)-, methyl ester;

Bicyclo[2.2.1 ]hepta-2,5-diene-2-carboxylic acid, 3-(2-chlorophenyl);

Bicyclo[2.2.1 ]hepta-2,5-diene-2-carboxylic acid, 3-(2-methoxyphenyl)-;

Bicyclo[2.2.1 ]hepta-2,5-diene-2-carboxylic acid, 3-(2-nitrophenyl)-;

Bicyclo[2.2.1 ]hepta-2,5-diene-2-cyano, 3-phenyl;

Bicyclo[2.2.1 ]hepta-2,5-diene-2-(4-cyanophenyl), 3-(4-methoxyphenyl);

Bicyclo[2.2.1 ]hepta-2,5-diene-2-(phenyl), 3-(phenyl);

Bicyclo[2.2.1 ]hepta-2,5-diene-2-(phenyl), 3-(4-methoxyphenyl);

Bicyclo[2.2.1 ]hepta-2,5-diene-2-(4-trifluoromethylphenyl), 3-(4- methoxyphenyl);

Bicyclo[2.2.1 ]hepta-2,5-diene-2-(4-trifluoromethylphenyl), 3-(4-dimethylamin); Bicyclo[2.2.1 ]hepta-2,5-diene-2-(2-chlorophenyl), 3-(2-chlorophenyl);

Bicyclo[2.2.1 ]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(4-cyanophenyl);

Bicyclo[2.2.1 ]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(2-thiophene);

Bicyclo[2.2.1 ]hepta-2,5-diene-2-(4-cyanophenyl), 3-(2-thiophene).

Another embodiment of the invention is a compound of Formula III:

Formula III

wherein

R ¹ represents a substituents selected from the group consisting of substituted phenyl, naphthyl, substituted naphthyl, heteroaryl, and substituted heteroaryl; wherein the substituted phenyl, substituted naphthyl, and substituted heteroaryl, are substituted at least in one of its ortho-positions; and are substituted with one or more substituents selected from the group of CN, C(Hal)3, R ³ , OR ³ , Hal, NO2, N(R ³ )2, NH(R ³ ), or with substituents forming steric bulk;

R ² represents aryl, substituted aryl, heteroaryl, and substituted heteroaryl, (which substituted aryl and substituted heteroaryl groups are substituted with one or more substituents selected from the group consisting of, CN, C(Hal)3, R ³ , OR ³ , Hal, N0 ₂ , N(R ³ ) ₂ , NH(R ³ )); CN; CO; COOR ⁴ ; COR ⁴ ; CON(R ⁴ ) ₂ ; C=C(CN) _2;

R ³ independently represents C1-C10 alkyl, optionally substituted with Hal;

R ⁴ independently represents H, C1-C10 alkyl, optionally substituted with Hal; with the proviso that the compound is not

Bicyclo[2.2.1]hepta-2, 5-diene, 2,3-bis(2-methoxyphenyl)-;

Bicyclo[2.2.1]hepta-2, 5-diene, 2,3-bis(2-chlorophenyl)-;

Bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(1 -naphthalenyl)-, methyl ester;

Bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(2-chlorophenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(2-methoxyphenyl)-;

Bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid, 3-(2-nitrophenyl)-;

Bicyclo[2.2.1]hepta-2,5-diene-2-cyano, 3-phenyl;

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-cyanophenyl), 3-(4-methoxyphenyl); Bicyclo[2.2.1]hepta-2,5-diene-2-(phenyl), 3-(phenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(phenyl), 3-(4-methoxyphenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-trifluoromethylphenyl) , 3-(4- methoxyphenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-trifluoromethylphenyl), 3-(4-dimethylamin); Bicyclo[2.2.1]hepta-2,5-diene-2-(2-chlorophenyl), 3-(2-chlorophenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(4-cyanophenyl);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-methoxyphenyl), 3-(2-thiophene);

Bicyclo[2.2.1]hepta-2,5-diene-2-(4-cyanophenyl), 3-(2-thiophene).

Formula I, II, and III include Ci-io alkyl groups. These can be linear, branched or cyclic when the number of atoms so allows. Example of alkyls are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octanyl, etc.

The compounds of the invention, according to Formula I and Formula III, are to be used for solar energy conversion and solar energy storage.

Compounds of Formula I can be included in functional material for thermal management. The functional material may be selected from functional coating, or functional fabrics, for example in form of films, like polymeric films. Polymer based MOST systems can be realized using two different

approaches, notably i) compounding into existing polymer matrices such as PMMA or PS, or ii) development of functional polymers with NBD containing monomers or monomers with pendant NBD side chains. A polymeric film may have a polymer structure which can be selected from polyesters, polyamides prepared from inter alia norbornadiene-2,3-diacarboxylic acids, or

norbornadiene-2-carboxylic acids. Another example of suitable polymer is norbornadiene being connected to a polyisoprene backbone in a heteroatom free polymer. Norbornadiene may be part of the polymer chain itself, or be linked to the polymer as a side arm. To include the norbornadiene

compounds, the compounds of Formula I, in a polymer may prevent undesired side reactions upon irradiation. Also, further substituents, like carbazole or benzophenones may be attached to the polymer to facilitate the photoisomerisation process. An example of solar energy collector is described in WO 2016/097199 A1. This solar energy collector is a non-limiting example of a suitable for including a molecular solar thermal system as energy converter.

A method of storing energy is another aspect of the invention. The method comprises the following steps:

i) providing an energy storage device comprising a molecular solar thermal system (MOST) including one or more compounds according to Formula I;

By including one or more compounds of Formula I there is a possibility to use a wider range of wave lengths when irradiating the MOST system.

Next step of the method is:

ii) illuminating the solar thermal fuel thereby converting the one or more compounds of Formula I from a lower-energy state to a higher-energy metastable state of corresponding Formula III.

Depending on the compound(s) included in the MOST system the wavelength of the irradiation is determined. For example, 150-700 nm.

Then, step iii)

iii) storing the one or more compound of Formula III in the higher- energy metastable state for a period of time.

It is a desire to be able to extend the period of storage, and to be able to predetermine the time period.

Step iv) is the release of the stored energy:

iv) providing a trigger to cause the compound of Formula III to revert to lower-energy state.

The energy released when the compound is reverted to the lower-energy state (step iv) is collected.

The trigger included in step iv) can be selected from thermal, catalytic, or electrocatalytic/ electrochemical activation. Examples of thermal activation includes heating the said compounds above 20 degrees C to a temperature where the conversion of quadricyclane to norbornadiene is accelerated, e.g. 70-150 degree Celsius range. Catalytic systems include cobalt, nickel, iron, platinum or palladium variants of porphyrines, cobalt phtalocyanines, cobalt salene, M0O3. The compounds of Formula III have a good kinetic stability which is to be used in its conversion into its parent compound according to Formula I. The reaction is a first order reaction, and follows the equation t _½ = In2/k (at room temperature, 25 degrees Celsius). Preferably, the t _½ shall be in the range of 1 hour to 7000 days.

The compounds of Formula I may be included in solar energy devices, like a solar energy collector. An example of a solar energy collector comprises -a wavelength converter;

-an energy converter being a molecular solar thermal system; wherein the molecular solar thermal system comprises one or more compounds according to Formula I as defined herein.

Also a method for storing the energy is provided by the invention. The method comprises an energy storage device comprising a molecular solar

thermal system comprising one or more compounds according to Formula I as defined herein; illuminating the solar thermal fuel thereby converting the compound of Formula I from a lower-energy state to a higher-energy metastable state of corresponding Formula III; storing the compound of Formula III in the higher-energy metastable state for a period of time; and providing a trigger to cause the compound of Formula III to revert to lower- energy state. The compounds as defined in Formula I, and the corresponding compounds of Formula III, have shown the surprising combination of properties when included in the method. By the method it is possible to control both (i) the absorption spectrum of the compound of Formula I; and the (ii) the energy storage half-life of the compound of Formula III. By the method herein described absorption spectrum according to (i) and the energy storage half-life according to (ii) can be controlled dependently of each other, or independently each other. The application of the method determines the desired result to be achieved, thus if one of (i) and (ii).

According to the invention, the method of storing energy herein described, wherein the compounds according to Formula I (and the corresponding compounds of Formula III) are chosen to control (i) the absorption spectrum of the compound of Formula I; and (ii) the energy storage half-life of the compound of Formula III. By that it is possible to store energy for at least 100 days, whilst simultaneously having an absorption spectrum where the wavelength of absorption onset is of at least 300 nm.

More specifically, the method of storing energy including the compounds according to Formula I (and the corresponding compounds of Formula III) as herein defined are chosen to control (i) the absorption spectrum of the compound of Formula I, such that the compound of Formula I has its longest (lowest energy) wavelength absorption having an onset of at least 300 nm, with a preferred absorption onset wavelength of at least 350 nm, with a very much preferred absorption onset wavelength of at least 400 nm; and (ii) the energy storage half-life of the compound of Formula III, such that that the compound of Formula III has an energy storage half-life of at least 100 days, with a preferred energy storage half-life of at least 500 days, with a much preferred energy storage half-life of at least 1000 days, with a very much preferred energy storage half-life of at least 2000 days.

The compounds of Formula I and Formula III having the above properties includes the R ¹ substitutent as herein defined, such as phenyl being substituted at its ortho position.

EXAMPLES

GENERAL METHODS

Cyclopentadiene was distilled by cracking dicyclopentadiene over iron filings and stored at -80 °C, prior to use. Tetrahydrofuran used for Suzuki coupling reactions was distilled over a sodium/benzophenone couple. All other chemicals were used as purchased from commercial sources. Purification of products was carried out by flash chromatography on silica gel (40-63 pm, 60 A). Thin-layer chromatography (TLC) was carried out using aluminum sheets precoated with silica gel. Infrared (IR) spectra recorded on a Perkin-Elmer Frontier FT-IR instrument as films evaporated from CDCI3 onto an ATR attachment, where relative intensities are denoted as vw (very weak), w (weak), m (medium), s (strong) and sh (shoulder). All melting points and heat release of neat quadricyclanes were recorded on a Mettler Toledo DSC 2 apparatus. ¹ H NMR (400 MHz) and ¹³ C NMR (100 MHz) spectra were recorded on a Varian 400 MHz instrument using the residual solvent as the internal standard (CDCI3, ¹ H 7.26 ppm and ¹³ C 77.16 ppm or ds-toluene, ¹ H 2.09 ppm, ¹³ C 20.40 ppm). All chemical shifts are quoted on the <5 scale (ppm), and all coupling constants (J) are expressed in Hz. All solution based spectroscopic measurements were performed in a 1 -cm path length cuvette on either a Cary 50 Bio or a Cary 100 UV-vis spectrophotometer, scanning the wavelength from 700 to 290 nm. Photoswitching experiments were performed using a Vilber Lourmet TLC lamp with a wavelength at 365 nm at 610 pw/cm ³ or Thorlabs LED M365F1. Photoswitching for wavelengths 310 nm and 340 nm were performed using Thorlabs LED lamps M310L3 and M340L4 respectively. The thermal back reaction was performed by heating the sample (cuvette) by a Peltier unit in the UV-Vis spectrophotometer.

Quantum Yields were measured by the published procedure using a high concentration regime. ^A Mass spectra were either acquired by gas

chromatography mass spectrometry (GC-MS) using an Agilent 7820A GC fitted with Agilent 5977E MSD electron ionization capabilities or electron spray ionization (ESI) using an Agilent 1260 Infinity fitted with an Agilent 6120 quadrupole for HRMS. Elemental analyses were performed at London Metropolitan University. Compounds 4o, ^B 5a,c,d,f,g,l,m, ^c 6 ^D were made by their respective literature methods.

Following examples A to H show the synthesis of compound 5 (as included in Method A and B). Examples 1A-1 Q show synthesis of the compound 2 (as included in Method A and B), thus compound of Formula I herein, and Examples 2A-2Q show the corresponding compound 7, the compound of Formula III herein.

For clarity, references (compound 1 , 2, 3, 4, 5, 6, etc) are made to the compounds included in the Method A and Method B above.

Example A

3-(2-Fluorophenyl)propiolonitrile (5d)

To stirring ice cooled DMF (50 mL, 0.65 mol), under a nitrogen atmosphere, was slowly added POCI3 (12 mL, 160 mmol). The ice bath was removed and the vessel allowed to stir for 15 min. The vessel was reimmersed in ice and 2 ^' -fluoroacetophenone 4d (5 ml_, 41 .1 mmol) was added and the flask was heated to 60 °C for 3 h. The cooled solution was poured into 20% aqueous NaOAc (200 ml_) and then allowed to cool and extracted into Et ₂ 0 (3 x 100 ml_). The ethereal extracts were dried over Na ₂ S0 ₄ , filtered and the solvent removed under reduced pressure. The crude residue was diluted in CHCI3 (150 ml_). To this ice cooled stirring solution was added (10.25 g, 40.4 mmol) and 28% aqueous NH3 (70 ml_) and stirred for 2 h at rt. Saturated aqueous NaS ₂ 03 (100 ml_) was added and the phases were separated. The organic phase was dried over Na2S0 ₄ , filtered and the solvent removed in vacuo. The residue was taken up in THF (100 ml_), and to this stirring solution was added portions of aqueous NaOH (4.45 g, 1 1 1 mmol, in 20 ml_ H2O) over 4 h. Saturated NaHC03 was added and the mixture extracted with Et ₂ 0 (2 x 100 ml_). The combined organics were dried over Na ₂ S0 ₄ , filtered and the solvent removed. The residue was purified by flash column chromatography (gradient elution of ChhCh/petroleum spirit 1 :4 to 3:7) to afford 5d (967 mg, 16%) as a white solid. Rf = 0.50 (ChteCh/n-hexane 3:7). M.p. = 43.0-43.7 °C. IR = 2267s, 2330m, 2148m, 1613sh, 1605m, 1572m cm ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 7.59 (dddd, J = 7.7, 6.7, 1 .8, 0.3 Hz, 2H), 7.53 (dddd, J = 8.4, 7.5, 5.3, 1 .8 Hz, 1 H), 7.23-7.14 (m, 2H) ppm. ¹³ C NMR (CDCIs, 100 MHz): d = 164.8 (d, J = 257.7 Hz), 135.1 , 134.1 (d, J = 8.3 Hz), 124.7 (d, J = 3.8 Hz),

1 16.4 (d, J = 20.0 Hz), 106.9 (d, J = 15.0 Hz), 105.3, 67.7 (d, J = 3.2 Hz) ppm, 1 C masked. HRMS (APCI, +ve) calcd for C9H5FN ([M+H] ⁺ ): 146.0401 ; exp 146.0407.

Example B

3-(3-Fluoro-4-methoxyphenyl)propiolonitrile (5e)

To stirring ice cooled DMF (50 ml_, 0.65 mol), under a nitrogen atmosphere, was slowly added POCI3 (10 ml_, 107 mmol). The ice bath was removed and the vessel allowed to stir for 15 min. The vessel was reimmersed in ice and 3 ^' -fluoro-4 ^' -methoxyacetophenone 4e (4.89 g, 29.1 mmol) was added and the flask was heated to 60 °C for 3 h. The cooled solution was poured into 20% aqueous NaOAc (200 ml_) and then allowed to cool. The precipitate was filtered and washed with hhO and the solid taken up in CHCI3 (150 ml_). To this stirring solution was added I2 (7.32 g, 28.8 mmol) and 28% aqueous NH3 (70 ml_) and stirred for 2 h. Saturated aqueous NaS ₂ 03 (100 ml_) was added and the phases were separated. The organic phase was dried over Na ₂ S0 ₄ , filtered and the solvent removed in vacuo. The residue was taken up in THF (100 ml_), and to this stirring solution was added aqueous NaOH (2.35 g, 58.8 mmol, in 25 ml_ H2O). Stirring was continued for 3 h, after which time, saturated NaHC03 (100 ml_) was added and most the THF was removed by rotary evaporation. This mixture was extracted with CH2CI2 (3 x 100 ml_), the combined organics were dried over Na2S0 ₄ , filtered and dry loaded onto celite and was purified by flash column chromatography (gradient elution of CH2Cl2/petroleum spirit 1 :1 to 3:2) to afford 5e (2.86 g, 56%) as a white solid. Rf = 0.39 (CH ₂ CI ₂ /n-hexane 1 :1 ). M.p. = 109.4-1 10.4 °C. IR = 3062w, 2984w, 2969w, 2934w, 2914vw, 2847w, 2261 s, 2146m, 1612m, 1571w, 1557w, 1516s, 1503m cm ¹ . ¹ H NMR (CDCI3, 400 MHz): d = 7.40 (dddd, J = 8.5, 2.0,

1 .3, 0.5 Hz, 1 H), 7.30 (dd, J = 1 1 .0, 2.0 Hz, 1 H), 6.96 (t, J = 8.5 Hz, 1 H), 3.94 (s, 3H) ppm. ¹³ C NMR (CDCI3, 100 MHz): d = 151 .7 (d, J = 249.7 Hz), 151 .4 (d, J = 10.6 Hz), 131 .3 (d, J = 3.7 Hz), 120.8 (d, J = 20.3 Hz), 1 13.5 (d, J =

2.6 Hz), 109.4 (d, J = 8.4 Hz), 105.6, 82.2 (d, J = 3.6 Hz) ppm. MS (GC-MS, +ve) = 175 (M ^+‘ ). HRMS (APCI, +ve) calcd for Ci ₀ H ₇ FNO ([M+H] ⁺ ): 176.0506; exp 176.0518.

Example C

3-(3,4-Dimethoxyphenyl)propiolonitrile (5h) ^E

To stirring ice cooled DMF (50 ml_, 0.65 mol) was slowly added POCI3 (10 ml_, 107 mmol). The ice bath was removed and the vessel allowed to stir for 15 min. The vessel was reimmersed in ice and 3 ^' ,4 ^' -dimethoxyacetophenone 4h (5.10 g, 28.3 mmol) was added and the flask was heated to 60 °C for 2 h. The cooled solution was poured into 20% aqueous NaOAc (200 ml_) and then allowed to cool. The precipitate was filtered and washed with H ₂ O and the solid taken up in CHCI3 (150 ml_). To this stirring solution was added I ₂ (7.12 g, 28.1 mmol) and 28% aqueous Nhb (70 ml_) and stirred for 4 h. Saturated aqueous NaS ₂ 03 (100 ml_) was added and the phases were separated. The organic phase was dried over Na ₂ S0 ₄ , filtered and the solvent removed. The residue was taken up in THF (100 ml_), and to this stirring solution was added aqueous NaOH (2.21 g, 55.3 mmol, in 20 ml_ hteO). Stirring was continued for 3 h, after which time, saturated NaHCOs (100 ml_) was added and most the THF was removed by rotary evaporation. This mixture was extracted with CH2CI2 (3 x 100 ml_), the combined organics were dried over Na2S0 ₄ , filtered, dry loaded onto celite and purified by flash column chromatography (gradient elution of CH2Cl2/petroleum spirit 1 :1 to 8:2) giving 5h (3.31 g, 62%) as a white solid. Rf = 0.56 (CH2Cl2/n-hexane 7:3). M.p. = 105.8-106.0 °C. IR = 3089w, 3073vw, 2999w, 2967w, 2944w, 2918w, 2904sh, 2842w, 2255s, 2138m, 1592s, 1536w, 1516s cm ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 7.26 (dd, J = 8.3, 1 .9 Hz, 1 H), 7.04 (d, J = 1 .9 Hz, 1 H), 6.85 (d, J = 8.3 Hz, 1 H), 3.92 (s, 3H), 3.88 (s, 3H) ppm. ¹³ C NMR (CDCIs, 100 MHz): d = 152.6, 149.0, 128.2, 1 15.2, 1 1 1 .3, 109.2, 105.9, 83.9, 62.4, 56.2 ppm.

Example D

3-(2,3,4-Trimethoxyphenyl)propiolonitrile (5j)

To stirring ice cooled DMF (100 ml_, 1 .30 mol), under a nitrogen atmosphere, was added POCI3 (25 ml_, 268 mmol) over a period of 30 min. The ice bath was removed and the vessel allowed to stir for 10 min. The vessel was reimmersed in ice and 3,4,5-trimethoxyacetophenone 4j (10.64 g, 50.6 mmol) dissolved in DMF (50 ml_) was added and the flask was heated to 70 °C for 1 .5 h. The cooled solution was poured into 20% aqueous NaOAc (400 ml_) and then allowed to cool and precipitate overnight. The precipitate was filtered and washed with H2O and the solid taken up in CHCI3 (200 ml_). To this stirring solution was added I2 (12.08 g, 47.6 mmol) and 28% aqueous NH3 (100 ml_) and stirred for 24 h. Saturated aqueous NaS ₂ 03 (100 ml_) was added and the phases were separated. The organic phase was dried over Na ₂ S0 ₄ , filtered and the solvent removed in vacuo. The residue was taken up in THF (100 ml_), and to this stirring solution was added aqueous NaOH (1 .92 g, 48.0 mmol, in 20 ml_ hteO). Stirring was continued for 1 .5 h, after which time, saturated NaHC03 was added and the THF was removed under vacuum. The resulting mixture was extracted with CH ₂ Cl ₂ (4 x 100 ml_). The combined organics were dried over Na2S0 ₄ , filtered and the solvent removed. The residue was purified by flash column chromatography (CH2CI2) to afford 5j (4.69 g, 43%) as a white solid. Rr = 0.69 (CH2CI2). M.p. = 89.7-90.1 °C. IR = 3099w, 3073vw, 3020sh, 3012w, 2970w, 2940m, 291 1 sh, 2870w, 2838m, 2278m, 2255s, 2237sh, 2141 m, 1577s, 1501 s cm ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 6.83 (s, 2H), 3.89 (s, 3H), 3.86 (s, 6H) ppm. ¹³ C NMR (CDCIs, 100 MHz): d = 153.4, 142.3, 1 12.1 , 1 10.8, 105.7, 83.5, 62.5, 61 .2, 56.5 ppm.

HRMS (APCI, +ve) calcd for C12H12NO3 ([M+H] ⁺ ): 218.0812; exp 218.0818.

Example E

3-(Benzo[c/][1 ,3]dioxol-5-yl)propiolonitrile (5k)

To stirring ice cooled DMF (50 ml_, 0.65 mol), under a nitrogen atmosphere, was slowly added POCI3 (12 ml_, 160 mmol). The ice bath was removed and the vessel allowed to stir for 15 min. The vessel was reimmersed in ice and 3 ^' ,4 ^' -(methylenedioxy)acetophenone 4k (5.31 g, 32.3 mmol) was added and the flask was heated to 60 °C for 3 h. The cooled solution was poured into 20% aqueous NaOAc (200 ml_) and then allowed to cool. The precipitate was filtered and washed with H2O and the solid taken up in CHCI3 (150 ml_). To this stirring solution was added I ₂ (8.09 g, 31 .9 mmol) and 28% aqueous NH3 (80 ml_) and stirred for 3 h. Saturated aqueous NaS ₂ 03 (100 ml_) was added and the phases were separated. The organic phase was dried over Na ₂ S0 ₄ , filtered and the solvent removed in vacuo. The residue was taken up in THF (100 ml_), and to this stirring solution was added aqueous NaOH (2.56 g, 64.0 mmol, in 10 mL H2O). Stirring was continued for 5 h, after which time, saturated NaHC03 was added and the mixture extracted with Et ₂ 0 (3 x 100 mL). The combined organics were dried over Na ₂ S0 ₄ , filtered, dry loaded onto celite, and purified by flash column chromatography (gradient elution of CH2Cl2/n-hexane 1 :1 to 3:2) to afford 5k (3.20 g, 58%) as a white solid. Rf = 0.35 (CH ₂ CI ₂ /n-hexane 3:2). M.p. = 1 12.0-1 12.2 °C. IR = 2920w, 2265s, 2252s, 2141 m, 1612m, 1600m, 1505m, 1491 s cm ¹ . ¹ H NMR (CDCIs, 400 MHz): 5 = 7.19 (dd, J = 8.1 , 1.5 Hz, 1 H), 6.99 (d, J = 1.5 Hz, 1 H), 6.82 (d, J = 8.1 Hz, 1 H), 6.05 (s, 2H) ppm. ¹³ C NMR (CDCIs, 100 MHz): d = 151.2, 147.9, 129.9, 112.6, 110.5, 109.2, 105.8, 102.2, 83.5, 62.2 ppm. MS (ESI, +ve) =

194 ([M+Na] ⁺ ). HRMS (APCI, +ve) calcd for C _IS H _M NO ([M+H] ⁺ ): 172.0393; exp 172.0417.

Example F

3-(4-(Dimethylamino)phenyl)propiolonitrile (5n) ^F

To stirring ice cooled DMF (30 ml_, 0.387 mol) was slowly added POCI3 (12 ml_, 128 mmol). The ice bath was removed and the vessel allowed to stir for 15 min. The vessel was reimmersed in ice and a solution of 4 -N,N- dimethylaminoacetophenone 4n (5.02 g in 80 ml_ DMF, 30.8 mmol) was added and the flask was heated to 60 °C for 3 h. The cooled solution was poured into 20% aqueous NaOAc (300 ml_) and then allowed to cool. The precipitate was filtered and washed with H2O and the solid taken up in CHCI3 (150 ml_). To this stirring solution was added I2 (18.56 g, 73.1 mmol) and 28% aqueous NH3 (70 ml_) and stirred for 24 h. Saturated aqueous NaS ₂ 03 (100 ml_) was added and the phases were separated. The organic phase was dried over Na ₂ S0 ₄ , filtered and the solvent removed. The residue was taken up in THF (100 ml_), and to this stirring solution was added portions of aqueous NaOH (5.57 g, 139 mmol, in 20 ml_ H2O) over 6 h. Saturated

NaHCOs (100 ml_) and Et20 (100 ml_) was added to the vessel and the phases separated. The aqueous phase was extracted with CH2CI2 (3 x 100 ml_), the combined organics were dried over Na2S0 ₄ , filtered, dry loaded onto celite and purified by flash column chromatography (gradient elution of CH2Cl2/petroleum spirit 2:3 to 1 :1 ) to afford 5n (3.13 g, 60%) as an orange solid. Rf = 0.40 (CH ₂ CI ₂ /n-hexane 1 :1 ). M.p. = 146.1-148.1 °C. IR =2917w, 2827vw, 2251 m, 2241 m, 2218m, 1606s, 1535m cm ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 7.45 (d, J = 9.1 Hz, 2H), 6.61 (d, J = 9.1 Hz, 2H), 3.04 (s, 6H) ppm. ¹³ C NMR (CDCIs, 100 MHz): <5 = 152.1 , 135.2, 111.6, 106.8, 102.6, 86.2,

62.4, 40.1 ppm. Example G

3-(4-(ferf-Butylthio)phenyl)propiolonitrile (5o)

To stirring ice cooled DMF (50 ml_, 0.65 mol), under a nitrogen atmosphere, was slowly added POCI3 (10 ml_, 107 mmol). The ice bath was removed and the vessel allowed to stir for 15 min. The vessel was reimmersed in ice and 4- terf-butylthioacetophenone 4o (5.00 g, 24.0 mmol) was added and the flask was heated to 60 °C for 3 h. The cooled solution was poured into 20% aqueous NaOAc (300 ml_) and then allowed to cool and extracted into Et ₂ 0 (3 x 100 ml_). The ethereal extracts were dried over Na ₂ S0 ₄ , filtered and the solvent removed under reduced pressure. The crude residue was taken up in CHCI3 (200 ml_). To this stirring solution was added (5.97 g, 23.5 mmol) and 28% aqueous NH3 (70 ml_) and stirred for 2 h. Saturated aqueous NaS ₂ 03 (100 ml_) was added and the phases were separated. The organic phase was dried over Na ₂ S0 ₄ , filtered and the solvent removed. The residue was taken up in THF (100 ml_), and to this stirring solution was added aqueous NaOFI (2.07 g, 51.8 mmol, in 20 ml_ FI2O). Stirring was continued for 2 h, after which time, saturated NaFICOs was added and the mixture extracted with Et ₂ 0 (3 x 100 ml_). The combined organics were dried over Na ₂ S0 ₄ , filtered and the solvent removed. The residue was purified by flash column chromatography (CFhCh/petroleum spirit 1 :3) to afford 5o (2.52 g, 49%) as reddish solid. R f = 0.37 (CFhCh/n-hexane 1 :3). M.p. = 51.7-53.5 °C. IR = 2974sh, 2963m, 2942w, 2923w, 2897w, 2864w, 2269sh, 2262s, 2145w, 1588m cm ¹ . ¹ H NMR (CDCI3, 400 MHz): d = 7.56 (s, 4H), 1.31 (s, 9H) ppm. ¹³ C NMR (CDCI ₃ , 100 MHz): d = 138.8, 137.1 , 133.3, 117.5, 105.5, 82.6,

64.3, 47.5, 31.2 ppm. MS (GCMS, +ve) = 215 (M ^+‘ ). Analysis calcd for C ₁₃ H ₁₃ NS (215.31 ); C 75.52, H 6.09, N 6.51.

Example H

3-(Thiophen-2-yl)propiolonitrile (5p) ^G

To stirring ice cooled DMF (100 ml_, 1.3 mol), under a nitrogen atmosphere, was slowly added POCI3 (30 ml_, 323 mmol). The ice bath was removed and the vessel allowed to stir for 30 min. The vessel was reimmersed in ice and a solution of 2-acetylthiophene 4p (8.6 ml_, 80 mmol in 40 ml_ DMF) was added dropwise and the resulting solution was heated to 70 °C for 4 h. The cooled solution was poured into 20% aqueous NaOAc (300 ml_) and then allowed to cool. The mixture was extracted with EtOAc (3 x 200 ml_) and the combined organic phases were washed with hhO (3 x 200 ml_) and brine (200 ml_), dried over Na ₂ S0 ₄ , filtered and concentrated in vacuo. The crude mixture was purified by flash column chromatography (ChhCh/petroleum spirit 1 :1 ) yielding 3-chloro-3-(thiophen-2-yl)acrylaldehyde as a slightly yellow oil, and due to stability was used immediately in the next step. ¹ H NMR (400 MHz, CDCIs): <5 = 10.14 (d, J = 6.9 Hz, 1 H), 7.66 (dd, J = 3.8, 1 .2 Hz, 1 H), 7.55 (dd, J = 5.1 , 1 .2 Hz, 1 H), 7.13 (dd, J = 5.1 , 3.8 Hz, 1 H), 6.61 (d, J = 6.9 Hz, 1 H).

To a solution of 3-chloro-3-(thiophen-2-yl)acrylaldehyde in CHCI3 (30 ml_) was added I2 (2.10 g, 8.27 mmol) and 28% aqueous NH3 (26 ml_). After 5 h, a saturated aqueous solution of Na2S203 (200 ml_) was added to the reaction flask. The phases were separated and the aqueous phase was extracted with CHCl3 (2 x 100 ml_), dried over Na ₂ S0 ₄ , filtered and concentrated under reduced pressure. The residue was dissolved in THF (30 ml_), where aqueous NaOH (1 .39 g, 34.8 mmol in 30 ml_ H2O) was added portion-wise over 4 h. A saturated aqueous solution of NaHCOs (100 ml_) was added to the reaction vessel and the mixture was extracted with Et ₂ 0 (3 x 100 ml_).

The combined organic phases were dried over Na ₂ S0 ₄ , filtered and concentrated under reduced pressure. Flash column chromatography

(CH2Cl2/petroleum spirit 3:7) of the crude residue gave 5p (245 mg, 2%) as a yellow oil, which was used directly in the next step. ¹ H NMR (400 MHz, CDCIs): d = 7.59 (dd, J = 3.7, 1 .2 Hz, 1 H), 7.53 (dd, J = 5.1 , 1 .2 Hz, 1 H), 7.08 (dd, J = 5.1 , 3.7 Hz, 1 H) ppm.

Example 1A

3-(4-Nitrophenyl)bicyclo[2.2.1]hepta-2,5-diene-2-carbonitril e (2a)

A vial suitable for microwave reactions was charged with cyclopentadiene (2.0 ml_, 23.8 mmol), 5a (1 .12 g, 6.51 mmol), BHT (20 mg) and chlorobenzene (2.0 ml_). The vial was sealed and heated to 100 °C for 16 h. The resulting reaction mixture was subjected to flash column chromatography (EtOAc/petroleum spirit 3:17) to afford 2a (1.26 g, 81 %) as a yellow solid. R f = 0.52 (CH ₂ CI ₂ /n-hexane 7:3). M.p. = 120.7-121.4 °C. IR = 3108w, 3077w, 2993w, 2948w, 2874w, 2201 m, 1595m, 1585sh, 1558w, 1517s, 1493w cm ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 8.27 (d, J = 9.0 Hz, 2H), 7.85 (d, J = 9.0 Hz, 2H), 6.98 (ddd, J = 5.1 , 3.1 , 0.8 Hz, 1 H), 6.92 (ddd, J = 5.1 , 3.2, 0.8 Hz, 1 H), 4.15 (ddtd, J = 3.2, 2.5, 1.6, 0.8 Hz, 1 H), 4.02 (ddtd, J = 3.1 , 2.5, 1.6, 0.8 Hz,

1 H), 2.35 (dt, J = 7.1 , 1.6 Hz, 1 H), 2.28 (dt, J = 7.1 , 1.6 Hz, 1 H) ppm. ¹³ C NMR (CDCIs, 100 MHz): d = 168.5, 148.2, 143.3, 140.5, 138.9, 127.3, 124.3, 122.3, 117.4, 72.0, 55.7, 54.4 ppm. MS (ESI, +ve) = 261 ([M+Na] ⁺ ). Analysis calcd for C _I4 H _I0 N ₂ O ₂ (238.25); C 70.58, H 4.23, N 11.76; found C 70.71 , H 4.30, N 11.66.

Example 1 B

3-(3-Nitrophenyl)bicyclo[2.2.1]hepta-2,5-diene-2-carbonitril e (2b)

A vial suitable for microwave reactions was charged with cyclopentadiene (2.0 ml_, 23.8 mmol), 5b (1.13 g, 6.56 mmol), BHT (15 mg) and

chlorobenzene (2.5 ml_). The vial was sealed and heated to 100 °C for 12 h. The resulting reaction mixture was dry loaded onto celite and subjected to flash column chromatography (CH ₂ CI ₂ /petroleum spirit 7:3) to afford 2b (1.35 g, 86%) as a white solid. R t - 0.45 (CH ₂ CI ₂ /n-hexane 7:3). M.p. = 141.3- 142.9 °C. IR = 3075w, 3028w, 2975w, 2938w, 2868w, 2198m, 1613w, 1590w, 1557w, 1529s cm ¹ . ¹ H NMR (CDCIs, 400 MHz): <5 = 8.42 (t, J = 2.0 Hz, 1 H), 8.25 (ddd, J = 8.0, 2.0, 1.0 Hz, 1 H), 8.16 (ddd, J = 8.0, 2.0, 1.0 Hz, 1 H), 7.63 (t, J = 8.0 Hz, 1 H), 6.99 (br dd, J = 5.0, 3.0 Hz, 1 H), 6.94 (br dd, J = 5.0, 3.1 Hz, 1 H), 4.18 (ddtd, J = 3.1 , 2.4, 1.6, 0.7 Hz, 1 H), 4.02 (ddtd, J = 3.0, 2.4, 1.6, 0.7 Hz, 1 H), 2.35 (dt, J = 7.0, 1.6 Hz, 1 H), 2.28 (dt, J = 7.0, 1.6 Hz, 1 H) ppm. ¹³ C NMR (CDCIs, 100 MHz): <5 = 168.5, 148.7, 143.3, 140.5, 134.7, 132.3, 130.2, 124.5, 121.1 , 120.9, 117.5, 72.0, 55.5, 54.4 ppm. MS (ESI, +ve) = 261 ([M+Na] ⁺ ). Analysis calcd for C _I4 H _I0 N ₂ O ₂ (238.25); C 70.58, H 4.23, N 11.76; found C 70.43, H 421 , N 11.63. Example 1C

3-(4-Fluorophenyl)bicyclo[2.2.1]hepta-2,5.diene-2-carbonitri le (2c)

A vial suitable for microwave reactions was charged with cyclopentadiene (3.0 ml_, 35.7 mmol), 5c (2.56 g, 17.6 mmol), BHT (5 mg) and chlorobenzene

(2 ml_). The vial was sealed and heated to 130 °C for 16 h. The resulting reaction mixture was subjected to flash column chromatography

(ChhCh/petroleum spirit 1 :2) and crystalized from n- hexane at -18 °C to afford 2c (2.18 g, 59%) as a white solid. R t = 0.59 (ChteCh/n-hexane 1 :1 ). M.p. = 34.7-36.0 °C. IR = 3073w, 2994w, 2947w, 2873w, 2197m, 1598m, 1559w,

1505s cm ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 7.75-7.70 (m, 2H), 7.15-7.09 (m, 2H), 6.94 (br dd, J = 5.1 , 3.0 Hz, 1 H), 6.85 (br dd, J = 5.1 , 3.1 Hz, 1 H), 4.09 (ddtd, J = 3.1 , 2.4, 1.7, 0.8 Hz, 1 H), 3.94 (ddtd, J = 3.0, 2.4, 1.7, 0.8 Hz, 1 H), 2.28 (dt, J = 6.9, 1.7 Hz, 1 H), 2.20 (dt, J = 6.9, 1.7 Hz, 1 H) ppm. ¹³ C NMR (CDCIs, 100 MHz): d = 169.8 (d, J = 1.2 Hz), 163.7 (d, J = 252.0 Hz), 143.4, 140.2, 129.5 (d, J = 3.4 Hz), 128.6 (d, J = 8.5 Hz), 118.5, 116.6 (d, J = 2.4 Hz), 116.2 (d, J = 21.9 Hz), 71.4, 55.1 , 54.4 ppm. MS (ESI, +ve) = 234

([M+Na] ⁺ ). Analysis calcd for C _I4 H _I0 FN (211.24); C 79.60, H 4.77, N 6.63; found C 79.48, H 4.78, N 6.66.

Example 1 D

3-(2-Fluorophenyl)bicyclo[2.2.1]hepta-2,5.diene-2-carbonitri le (2d)

A vial suitable for microwave reactions was charged with cyclopentadiene (2.0 ml_, 24.0 mmol), 5d (950 mg, 6.55 mmol), BHT (5 mg) and

chlorobenzene (2.5 ml_). The vial was sealed and heated to 120 °C for 24 h. The resulting reaction mixture was subjected to flash column chromatography (CH2Cl2/petroleum spirit 1 : 1 ) to afford 2d (969 mg, 70%) as a white solid. R f = 0.57 (CH ₂ CI ₂ /n-hexane 1 :1 ). M.p. = 66.0-66.5 °C. IR = 3073w, 2992w,

2947w, 2874w, 2203m, 1615w, 1597w, 1573sh, 1562w cm ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 7.58 (td, J = 7.5, 1.8 Hz, 1 H), 7.36 (dddd, J = 8.3, 7.5, 5.2, 1.8 Hz, 1 H), 7.19 (td, J = 7.5, 1.2 Hz, 1 H), 7.12 (ddd, J = 11.0, 8.3, 1.2 Hz, 1 H), 6.96 (br dd, J = 5.0, 3.1 Hz, 1 H), 6.91 (br dd, J = 5.0, 3.1 Hz, 2H), 4.14 (ddtd, J = 3.1 , 2.4, 1 .6, 0.8 Hz, 1 H), 3.92 (ddtd, J = 3.1 , 2.4, 1 .6, 0.8 Hz, 1 H), 2.34 (dt, J = 6.9, 1 .6 Hz, 1 H), 2.21 (dt, J = 6.9, 1 .6 Hz, 1 H) ppm. ¹³ C NMR (CDCIs,

100 MHz): d = 167.9 (d, J = 1 .8 Hz), 159.7 (d, J = 252.1 Hz), 142.9 (d, J = 0.6 Hz), 141 .6 (d, J = 0.8 Hz), 131 .6 (d, J = 8.6 Hz), 128.9, 124.6, 122.0 (d, J =

13.1 Hz), 121 .7 (d, J = 1 .3 Hz), 1 17.5, 1 16.4 (d, J = 21 .8 Hz), 72.2, 56.3 (d, J = 5.0 Hz), 54.6 ppm. MS (ESI, +ve) = 234 ([M+Na] ⁺ ). Analysis calcd for CMH IOFN (21 1 .24); C 79.60, H 4.77, N 6.63; found C 79.50, H 4.82, N 6.69.

Example 1 E

3-(3-Fluoro-4-methoxyphenyl)bicyclo[2.2.1]hepta-2,5-diene-2- carbonitrile

(2e)

A vial suitable for microwave reactions was charged with cyclopentadiene (2.5 ml_, 29.7 mmol), 5e (1 .1 1 g, 6.34 mmol), BHT (8 mg) and chlorobenzene (2.5 ml_). The vial was sealed and heated to 120 °C for 24 h. The resulting reaction mixture was subjected to flash column chromatography

(CH2Cl2/petroleum spirit 3:2), giving recovered 5e (1 19 mg), followed by 2e, which was crystalized from Et ₂ 0/heptane at -18 °C to afford the pure material (1 .30 g, 85%, 95% based on recovered 5e) as a white solid. R f = 0.35

(CH ₂ CI ₂ /n-hexane 3:2). M.p. = 58.5-60.0 °C. IR = 3072w, 2988w, 2945w,

2913vw, 2873w, 2844w, 2195m, 1615m, 1570m, 1560w, 1513s cm ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 7.52 (ddd, J = 8.6, 2.2, 1 .2 Hz, 1 H), 7.47 (dd, J = 12.3,

2.2 Hz, 1 H), 6.99 (t, J = 8.6 Hz, 1 H), 6.92 (br dd, J = 5.1 , 3.0 Hz, 1 H), 6.82 (br dd, J = 5.1 , 3.1 Hz, 1 H), 4.05 (ddtd, J = 3.1 , 2.4, 1 .6, 0.7 Hz, 1 H), 3.92-3.90 (m, 4H), 2.25 (dt, J = 6.9, 1 .6 Hz, 2H), 2.17 (dt, J = 6.9, 1 .6 Hz, 1 H) ppm. ¹³ C NMR (CDCIs, 100 MHz): <5 = 169.3 (d, J = 2.4 Hz), 152.2 (d, J = 247.1 Hz),

149.2 (d, J = 10.9 Hz), 143.3, 140.1 , 126.4 (d, J = 6.8 Hz), 123.3 (d, J = 3.4 Hz), 1 18.6, 1 15.5, 1 14.3 (d, J = 19.4 Hz), 1 13.3 (d, J = 2.3 Hz), 71 .0, 56.4, 55.0, 54.1 ppm. MS (ESI, +ve) = 264 ([M+Na] ⁺ ). Analysis calcd for

C15H12FNO (241 .27); C 74.68, H 5.01 , N 5.81 ; found C 74.56, H 4.94, N 5.76.

Example 1 F

3-(2-Methoxyphenyl)bicyclo[2.2.1]hepta-2,5-diene-2-carbonitr ile (2f) A nitrogen sparged solution of 6 (2.15 g, 1 .42 mmol) in toluene (10 ml_) was added to a de-aerated flask containing 2-methoxyphenylboronic acid (310 mg, mmol), K ₂ CO3 (891 mg, 6.45 mmol), RuPhos (64 mg, 0.137 mmol) and Pd(OAc) ₂ (15 mg, 0.067 mmol) under nitrogen, followed by nitrogen purged H ₂ O (3 ml_). The biphasic mixture was stirred at 60 °C for 4 d. After which time, the vessel was allowed to cool to ambient temperature, quenched with saturated aqueous NH ₄ CI (10 ml_) and diluted with water (10 ml_). The mixture was extracted with toluene (3 x 50 ml_), the combined organics were dried over Mg2S0 ₄ , filtered and the solvent removed under reduced pressure. The residue was subjected to flash column chromatography

(ChhCh/petroleum spirit 3:1 ) to give 2f (102 mg, 32%) as a pasty white solid. R f = 0.41 (ChteCh/n-hexane 3:1 ). IR = 3072vw, 2994w, 2975w, 2944w, 2905sh, 2872vw, 2839w, 2200m, 1594m, 1575sh, 1560 cm ¹ . ¹ H NMR

(CDCI3, 400 MHz): d = 7.39 (dd, J = 7.5, 1 .7 Hz, 1 H), 7.35 (ddd, J = 8.3, 7.5,

1 .7 Hz, 1 H), 6.99 (ddd, J = 7.5, 7.5, 1 .1 Hz, 1 H), 6.95-6.90 (m, 3H), 6.87 (br dd, J = 5.0, 3.1 Hz, 1 H), 4.09 (ddtd, J = 3.1 , 2.4, 1 .6, 0.8 Hz, 1 H), 3.90-3.85 (m, 4H), 2.29 (dt, J = 6.8, 1 .6 Hz, 1 H), 2.15 (dt, J = 6.8, 1 .6 Hz, 1 H) ppm. ¹³ C NMR (CDCI ₃ , 100 MHz): <5 = 170.5, 157.1 , 142.7, 141 .8, 131 .2, 128.7, 123.4, 120.8, 1 12.0, 1 18.1 , 1 1 1 .3, 71 .6, 56.6, 55.3, 54.4 ppm. MS (ESI, +ve) = 246 ([M+Na] ⁺ ). Analysis calcd for C15H13NO (223.28); C 80.69, H 5.87, N 6.27; found C 80.73, H 5.83, N 6.28.

Example 1 G

3-(3-Methoxyphenyl)bicyclo[2.2.1]hepta-2,5-diene-2-carbonitr ile (2g)

A vial suitable for microwave reactions was charged with cyclopentadiene (2.0 ml_, 24.0 mmol), 5g (1 .34 g, 8.53 mmol), BHT (5 mg) and chlorobenzene (2.0 ml_). The vial was sealed and heated to 130 °C for 24 h. The mixture was directly subjected to flash column chromatography (gradient elution of CH2Cl2/n-hexane 1 :4 to CH2CI2) resulting in the recovery of 5g (19 mg, 1 %).

A succesive column (gradient elution of EtOAc/n-hexane 1 :19 to 2:23) gave 2g (1 .65 g, 87%, 88% based on recovered 5g) as a pale yellow glassy solid.

R f = 0.38 (CH ₂ Cl ₂ /petroleum spirit 3:2). M.p. = 55.0-56.5 °C. IR = 3072vw, 2997w, 2979sh, 2944w, 2915sh, 2874vw, 2836vw, 2196s, 1599s, 1558m cm ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 7.38-7.32 (m, 1 H), 7.31-7.27 (m, 2H), 6.97-6.92 (m, 2H), 6.86 (br dd, J = 5.0, 3.3 Hz, 1 H), 4.11 (ddtd, J = 3.3, 2.5,

1.6, 0.8 Hz, 1 H), 3.94 (ddtd, J = 3.2, 2.5, 1.6, 0.9 Hz, 1 H), 3.85 (s, 3H), 2.28 (dt, J = 6.9, 1.6 Hz, 1 H), 2.19 (dt, J = 6.9, 1.6 Hz, 1 H) ppm. ¹³ C NMR (CDCIs, 100 MHz): <5 = 170.9, 159.9, 143.2, 140.5, 134.5, 130.0, 119.0, 118.5, 117.3,

116.3, 111.6, 71.4, 55.5, 55.1 , 54.4 ppm. MS (ESI, +ve) = 246

([M+Na] ⁺ ). HRMS (APCI, +ve) calcd for C _IS H _M NO ([M+H] ⁺ ): 224.1070; exp 224.1076.

Example 1 H

3-(3,4-Dimethoxyphenyl)bicyclo[2.2.1]hepta-2,5-diene-2-carbo nitrile (2h)

A vial suitable for microwave reactions was charged with cyclopentadiene (2.5 ml_, 29.7 mmol), 5h (1.13 g, 6.04 mmol), BHT (15 mg) and

chlorobenzene (2.5 ml_). The vial was sealed and heated to 130 °C for 16 h. The resulting reaction mixture was subjected to flash column chromatography (CH2CI2), firstly giving recovered 5h (175 mg) and crude 2h, which was crystalized from Et ₂ 0/heptane at -18 °C to afford the pure material (1.28 g, 84%, 99% based on recovered 5h) as a white solid. R f = 0.35 (CH2CI2). M.p.

= 100.6-101.4 °C. IR = 2998w, 2941 w, 2907w, 2871 w, 2838w, 2191 m,

1599w, 1570w, 1558w, 1513s cm ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 7.46 (d, J = 2.1 Hz, 1 H), 7.23 (dd, J = 8.4, 2.1 Hz, 1 H), 6.92 (br dd, J = 5.1 , 3.0 Hz, 1 H), 6.90 (d, J = 8.4 Hz, 1 H), 6.82 (br dd, J = 5.1 , 3.1 Hz, 1 H), 4.11 (ddtd, J = 3.1 , 2.5, 1.6, 0.7 Hz, 1 H), 3.93 (s, 3H), 3.92-3.90 (m, 4H), 2.25 (dt, J = 6.8, 1.6 Hz, 1 H), 2.17 (dt, J = 6.8, 1.6 Hz, 1 H) ppm. ¹³ C NMR (CDCIs, 100 MHz): d =

170.6, 150.9, 149.2, 143.3, 140.1 , 126.3, 120.0, 119.2, 114.0, 110.9, 109.4, 70.8, 56.1 , 54.8, 53.9 ppm, 1 C masked. MS (ESI, +ve) = 276 ([M+Na] ⁺ ).

HRMS (APCI, +ve) calcd for C _I6 H _I6 N0 ₂ ([M+H] ⁺ ): 254.1176; exp 254.1175. Analysis calcd for C _I6 H _I5 N0 ₂ (253.30); C 75.87, H 5.97, N 5.53; found C 76.03, H 6.02, N 5.65.

Example 11 3-(2,4-Dimethoxyphenyl)bicyclo[2.2.1]hepta-2,5-diene-2-carbo nitrile (2i)

A nitrogen sparged mixture consisting of 6 (507 mg, 3.34 mmol), 2,4- dimethoxyphenylboronic acid (915 mg, 5.02 mmol), CsF (2.34 g, 15.4 mmol), Pd2dba3 (310 mg, 0.338 mmol) and a solution of PtBu3 (1.0 ml_, 1 M in toluene, 1.0 mmol) in dry THF (20 ml_) was heated to 60 °C for 1 d. The cooled reaction mixture was filtered through a pad of S1O2, the volatiles removed under reduced pressure and the crude residue subjected to flash column chromatography (EtOAc/n-hexane 9:41 ). An additional column

(EtOAc/toluene 3:497) of this material resulted in the isolation of pure 2i (557 mg, 66%) as a yellowish oil. R t = 0.45 (EtOAc/n-hexane 1 :4). IR = 3072vw, 2997w, 2971 w, 2942w, 2870w, 2839w, 2196m, 1606s, 1591 sh, 1571 m,

1561 sh, 1501 m cm ¹ . ¹ H NMR (CDCI3, 400 MHz): d = 7.37 (d, J = 8.5 Hz, 1 H), 6.91 (br dd, J = 5.0, 3.0 Hz, 1 H), 6.83 (br dd, J = 5.0, 3.2 Hz, 1 H), 6.51 (dd, J = 8.5, 2.4 Hz, 1 H), 6.47 (d, J = 2.4 Hz, 1 H), 4.08 (ddtd, J = 3.2, 2.3, 1.6, 0.8 Hz, 1 H), 3.87-3.83 (m, 4H), 3.83 (s, 3H), 2.25 (dt, J = 6.8, 1.6 Hz, 1 H), 2.12 (dt, J = 6.8, 1.6 Hz, 1 H) ppm. ¹³ C NMR (CDCI3, 100 MHz): d = 170.0, 162.5, 158.5, 142.8, 141.5, 129.7, 118.7, 117.4, 116.5, 104.8, 98.9, 71.2, 56.5, 55.6, 55.3, 54.3 ppm. MS (ESI, +ve) = 276 ([M+Na] ⁺ ). HRMS (ESI, +ve) calcd for Ci ₆ Hi ₅ N0 ₂ Na ([M+Na] ⁺ ): 276.0995; exp 276.0986.

Example 1J

3-(3,4,5-Trimethoxyphenyl)bicyclo[2.2.1]hepta-2,5-diene-2-ca rbonitrile

(2j)

A vial suitable for microwave reactions was charged with cyclopentadiene (2.0 ml_, 23.9 mmol), 5 j (1.19 g , 5.49 mmol), BHT (6 mg) and chlorobenzene (2.0 ml_). The vial was sealed and heated to 130 °C for 24 h. The resulting reaction mixture was subjected to flash column chromatography (gradient elution of CH2Cl2/n-hexane 3:1 to EtOAc/CH2Cl2 1 :49), first giving recovered 5j (129 mg) and crude 2j which was crystalized from CH2Cl2/heptane to afford the pure material (1.16 g, 75%, 84% based on recovered 5j). R f = 0.26

(CH2CI2). M.p. = 93.2-94.9 °C. IR = 2996w, 2972sh, 2941w, 2907sh, 2873w, 2839w, 2831 sh, 2194m, 1589sh, 1572m, 1559w, 1504 cm ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 6.99 (s, 2H), 6.94 (br dd, J = 5.0, 3.0 Hz, 1 H), 6.85 (br dd, J = 5.1 , 3.2 Hz, 1 H), 4.10 (ddtd, J = 3.2, 2.4, 1 .6, 0.7 Hz, 1 H), 3.94-3.91 (m, 4H), 3.88 (s, 3H), 2.28 (dt, J = 6.8, 1 .6 Hz, 1 H), 2.19 (dt, J = 6.8, 1 .6 Hz, 1 H) ppm. ¹³ C NMR (CDCIs, 100 MHz): d = 170.9, 153.5, 143.4, 140.2, 140.0, 128.7, 1 18.9, 1 16.1 , 104.1 , 71 .2, 61 .1 , 56.4, 55.0, 54.2 ppm. MS (ESI, +ve) = 306 ([M+Na] ⁺ ). Analysis calcd for C ₁₇ H ₁₇ NO3 (283.33); C 72.07, H 6.05, N 4.94; found C 77.12, H 5.98, N 5.00.

Example 1 K

3-(Benzo[c/][1 ,3]dioxol-5-yl)bicyclo[2.2.1]hepta-2,5-diene-2-carbonitrile

(2k)

A vial suitable for microwave reactions was charged with cyclopentadiene (2.5 ml_, 29.7 mmol), 5k (1 .10 g, 6.43 mmol), BHT (14 mg) and

chlorobenzene (2.5 ml_). The vial was sealed and heated to 120 °C for 16 h. The resulting reaction mixture was subjected to flash column chromatography (gradient elution of CH2Cl2/petroleum spirit 1 :1 to 7:3) firstly gave recovered 5k (307 mg), followed by 2k (1 .05 g, 69%, 95% based on recovered 5k) which was isolated as a white solid. R f = 0.45 (CH2Cl2/n-hexane 7:3). M.p. = 84.9-86.2 °C. IR = 3074vw, 2991 w, 2946w, 2903w, 2874w, 2782vw, 2195m,

1620w, 1604w, 1579w, 1558w, 1532w, 1504s, 1488s cm ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 7.28 (dd, J = 1 .9, 0.4 Hz, 1 H), 7.22 (dd, J = 8.2, 1 .9 Hz, 1 H), 6.91 (br dd, J = 5.1 , 3.2 Hz, 1 H), 6.85 (dd, J = 8.2, 0.4 Hz, 1 H), 6.81 (br dd, J = 5.1 , 3.2 Hz, 1 H), 6.01 (q, J = 1 .3 Hz, 2H), 4.04 (ddtd, J = 3.2, 2.4, 1 .6, 0.8 Hz, 1 H), 3.90 (ddtd, J = 3.2, 2.5, 1 .6, 0.8 Hz, 1 H), 2.24 (dt, J = 6.9, 1 .6 Hz,

1 H), 2.15 (dt, J = 6.9, 1 .6 Hz, 1 H) ppm. ¹³ C NMR (CDCIs, 100 MHz): <5 = 170.3, 149.3, 148.3, 143.3, 140.0, 127.6, 121 .5, 1 18.9, 1 14.6, 108.6, 106.7,

101 .7, 70.9, 54.9, 54.5 ppm. MS (ESI, +ve) = 260 ([M+Na] ⁺ ). Analysis calcd for C ₁₅ H _{1 1} NO ₂ (237.26); C 75.94, H 4.67, N 5.90; found C 75.99, H 4.59, N 5.97.

Example 1 L 3-(Naphthalen-1-yl)bicyclo[2.2.1]hepta-2,5-diene-2-carbonitr ile (2I)

A vial suitable for microwave reactions was charged with cyclopentadiene (6.0 ml_, 71.3 mmol), 5I (3.27 g, 18.5 mmol), BHT (5 mg) and chlorobenzene (8.0 ml_). The vial was sealed and heated to 120 °C for 20 h. The resulting reaction mixture was subjected to flash column chromatography

(ChhCh/petroleum spirit 2:3) allowing for the recovery of 5I (1.35 g). A second flash column (gradient elution of EtOAc/n-hexane 1 :24 to 3:47) of the crude isolate gave 2I as a pale yellow oil (1.34 g, 30%, 50% based on recovered 5I). R f = 0.45 ChteCh/n-hexane 1 :1 ). IR = 3059w, 3049sh, 2993w, 2982sh, 2944w, 2871 w, 2204m, 1607sh, 1588w, 1560w, 1509m cm ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 7.93-7.86 (m, 2H), 7.77-7.71 (m, 1 H), 7.58-7.52 (m, 2H), 7.49 (dd, J = 8.2, 7.1 Hz, 1 H), 7.37 (dd, J = 7.1 , 1.2 Hz, 1 H), 7.08 (ddd, J = 5.1 , 3.0, 0.7 Hz, 1 H), 7.01 (ddd, J = 5.1 , 3.1 , 0.8 Hz, 1 H), 4.08 (ddtd, J = 3.1 , 2.5, 1.6, 0.7 Hz, 1 H), 4.05 (ddtd, J = 3.0, 2.5, 1.6, 0.7 Hz, 1 H), 2.60 (dt, J = 6.8, 1.6 Hz,

1 H), 2.33 (dt, J = 6.8, 1.6 Hz, 1 H) ppm. ¹³ C NMR (CDCIs, 100 MHz): d =

173.6, 143.2, 141.4, 133.8, 132.5, 130.3, 129.9, 128.7, 126.6, 126.3, 125.3, 125.1 , 125.1 , 121.9, 117.2, 72.9, 58.0, 54.6 ppm. MS (ESI, +ve) = 266

([M+Na] ⁺ ). HRMS (ESI, +ve) calcd for Ci ₈ Hi ₄ NNa ([M+H] ⁺ ): 244.1121 ; exp 244.1119.

Example 1M

3-(Naphthalen-2-yl)bicyclo[2.2.1]hepta-2,5-diene-2-carbonitr ile (2m)

A vial suitable for microwave reactions was charged with cyclopentadiene (5.0 ml_, 59.5 mmol), 5m (2.41 g, 13.6 mol), BHT (5 mg) and chlorobenzene (6.0 ml_). The vial was sealed and heated to 110 °C for 20 h. The crude reaction mixture purified by flash column chromatography (gradient elution of CH2Cl2/petroleum spirit 1 :4 to 2:3) affording 2m as a crystalline white solid (2.20 g, 66%). Rr = 0.53 (CH ₂ CI ₂ /n-hexane 1 :1 ). M.p. = 97.7-99.3 °C. IR = 3057w, 2992w, 2981 sh, 2944w, 2922sh, 2871 w, 2853sh, 2195s, 1600w,

1584w, 1568w, 1557w, 1505w cm ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 8.08 (d,

J = 1.8 Hz, 1 H), 7.96 (dd, J = 8.6, 1.8 Hz, 1 H), 7.93-7.81 (m, 3H), 7.56-7.50 (m, 2H), 6.97 (dd, J = 5.0, 3.1 Hz, 1 H), 6.93 (dd, J = 5.0, 3.1 Hz, 1 H), 4.28 (ddtd, J = 3.1 , 2.3, 1.6, 0.7 Hz, 1 H), 3.99 (ddtd, J = 3.1 , 2.3, 1.6, 0.8 Hz, 1 H), 2.34 (dd, J = 6.9, 1.6 Hz, 1 H), 2.25 (dt, J = 6.9, 1.6 Hz, 1 H) ppm. ¹³ C NMR (CDCIs, 100 MHz): d = 170.7, 143.3, 140.4, 134.0, 133.2, 130.7, 128.9, 128.8, 127.9, 127.5, 126.9, 126.4, 123.8, 118.8, 117.2, 71.2, 55.3, 54.3 ppm. MS (ESI, +ve) = 266 ([M+Na] ⁺ ). Analysis calcd for CisHisN (243.31 ); C 88.86, H 5.39, N 5.76; found C 88.75, H 5.47, N 5.63.

Example 1 N

3-(4-(Dimethylamino)phenyl)bicyclo[2.2.1]hepta-2,5-diene-2-c arbonitrile

(2n)

A vial suitable for microwave reactions was charged with cyclopentadiene (2.0 ml_, 23.8 mmol), 5n (1.15 g, 6.76 mmol), BHT (5 mg) and chlorobenzene (2.0 ml_). The vial was sealed and heated to 130 °C for 24 h. The resulting reaction mixture was by dry loaded onto celite and subjected to flash column chromatography (gradient elution of toluene/n-hexane 1 :1 to toluene), firstly giving unreacted 5n (331 mg) followed by an impure sample containing 2n. This crude mixture was further purified by a second flash column (EtOAc In- hexane 1 :9) and a third flash column (EtOAc/toluene 3:247), followed finally by recrystallization from hot EtOAc/heptane to afford 2n (328 mg, 21 %, 29% based on recovered 5n) as a yellowish solid. Rf = 0.32 (toluene). M.p. = 151.5-152.8 °C. IR = 3007w, 2981 w, 2945w, 2901 w, 2871 w, 2820w, 2186s, 1612s, 1577m, 1561w, 1523s cm ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 7.70 (d, J = 9.1 Hz, 2H), 6.90 (br dd, J = 5.1 , 2.9 Hz, 1 H), 6.77 (br dd, J = 5.1 , 3.2 Hz,

1 H), 6.70 (d, J = 9.1 Hz, 2H), 4.11 (ddtd, J = 3.2, 2.4, 1.7, 0.7 Hz, 1 H), 3.86 (ddtd, J = 3.2, 2.4, 1.7, 0.9 Hz, 1 H), 3.02 (s, 6H), 2.20 (dt, J = 6.7, 1.7 Hz,

1 H), 2.11 (dt, J = 6.7, 1.7 Hz, 1 H) ppm. ¹³ C NMR (CDCIs, 100 MHz): <5 =

170.4, 151.4, 143.3, 139.6, 128.1 , 121.1 , 120.0, 111.6, 109.6, 69.9, 54.4,

53.5, 40.1 ppm. MS (ESI, +ve) = 237 ([M+H] ⁺ ). Analysis calcd for C16H16N2 (236.32); C 81.32, H 6.82, N 11.85; found C 81.41 , H 6.91 , N 11.84.

Example 10 3-(4-(ferf-Butylthio)phenyl)bicyclo[2.2.1]hepta-2,5-diene-2- carbonitrile

(2o)

A vial suitable for microwave reactions was charged with cyclopentadiene (2.0 ml_, 23.8 mmol), 5o (2.06 g, 9.57 mmol), BHT (5 mg) and chlorobenzene (2.0 ml_). The vial was sealed and heated to 100 °C for 24 h. The resulting reaction mixture was subjected to flash column chromatography

(CH ₂ CI ₂ /petroleum spirit 1 :2), firstly giving unreacted 5o (594 mg), followed by 2o (1 .77 g, 66%, 88% based on recovered 5o) as an off white solid. R t = 0.42 (CH ₂ CI ₂ /n-hexane 1 :1 ). M.p. = 65.0-65.7 °C. IR = 3073w, 2970s, 2961 s, 2942m, 2923m, 2871 m, 2863m, 2198s, 1588w, 1559w, 1543vw crTV ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 7.68 (d, J = 8.6 Hz, 2H), 7.58 (d, J = 8.6 Hz, 2H), 6.94 (br dd, J = 5.0, 3.1 Hz, 1 H), 6.87 (br dd, J = 5.0, 3.2 Hz, 1 H), 4.12 (ddtd, J = 3.2, 2.4, 1 .7, 0.8 Hz, 1 H), 3.95 (ddtd, J = 3.1 , 2.4, 1 .7, 0.8 Hz, 1 H), 2.29 (dt, J = 6.9, 1 .7 Hz, 1 H), 2.21 (dt, J = 6.9, 1 .7 Hz, 1 H), 1 .31 (s, 9H) ppm. ¹³ C NMR (CDCIs, 100 MHz): <5 = 170.1 , 143.2, 140.4, 137.7, 135.6, 133.2, 126.4,

1 18.4, 1 17.8, 71 .4, 55.2, 54.2, 46.9, 31 .2 ppm. MS (ESI, +ve) = 320 ([M+K] ⁺ ). Analysis calcd for CisHigNS (281 .42); C 76.82, H 6.81 , N 4.98; found C 76.72, H 6.73, N 5.08.

Example 1 P

3-(Thiophen-2-yl)bicyclo[2.2.1]hepta-2,5-diene-2-carbonitril e (2p)

A vial suitable for microwave reactions was charged with cyclopentadiene (1 .0 ml_, 12 mmol), 5p (245 mg, 1 .84 mmol), BHT (3 mg) and chlorobenzene (1 .0 ml_). The vial was sealed and heated to 100 °C for 20 h. The resulting mixture was purified by flash column chromatography (gradient elution of CH ₂ CI ₂ /n-hexane 1 :4 to 2:3), followed by a second column (EtOAc/n-hexane 2:23) yielding 2p as a tan solid (197 mg, 54%). R t - 0.44 (CH ₂ CI ₂ /n-hexane 1 :1 ). M.p. = 40.3-41 .6 °C. IR = 3106w, 3075w, 2985w, 2945w, 2871 w, 2192s, 1597sh, 1581 m, 1559w, 1504w cm ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 7.56 (dd, J = 3.8, 1 .1 Hz, 1 H), 7.49 (dd, J = 5.1 , 1 .1 Hz, 1 H), 7.13 (dd, J = 5.1 , 3.8 Hz, 1 H), 6.92 (br dd, J = 5.1 , 3.1 Hz, 1 H), 6.80 (br dd, J = 5.1 , 3.1 Hz, 1 H), 4.06 (ddtd, J = 3.2, 2.4, 1 .7, 0.7 Hz, 1 H), 3.91 (ddtd, J = 3.1 , 2.5, 1 .7, 0.9 Hz, 1 H), 2.28 (dt, J = 6.9, 1.7 Hz, 1 H), 2.17 (dt, J = 6.9, 1.7 Hz, 1 H) ppm. ¹³ C NMR (CDCIs, 100 MHz):□ = 163.9, 143.5, 139.8, 137.0, 129.3, 128.4, 128.0,

118.4, 113.4, 70.8, 55.3, 54.4 ppm. MS (ESI, +ve) = 222 ([M+Na] ⁺ ). Analysis calcd for C ₁₂ H9NS (199.27); C 72.33, H 4.55, N 7.03; found C 72.19, H 4.72,

N 7.03.

Example 1Q

3-(Thiophen-2-yl)bicyclo[2.2.1]hepta-2,5-diene-2-carbonitril e (2q)

To an argon purged solution of 6 (505 mg, 3.33 mmol) and thiophene-3- boronic acid (679 mg, 5.31 mmol) in anhydrous THF (30 ml_) was added Pd2dba3 (458 mg, 0.500 mmol) and CsF (2.27 g, 14.9 mmol) followed by t- BU3P (1 ml_, 1 M in toluene, 1 mmol). The reaction mixture was stirred at reflux point overnight, before cooling to ambient temperature, where it was filtered through a plug of flash silica (CH2CI2). Flash column chromatography

(CH2Cl2/n-hexane 1 :1 ) followed by a second column (n- hexane/toluene 3:7) gave 2q as a slightly yellow oil (336 mg, 51 %). Rf = 0.42 (CH2Cl2/n-hexane 1 :1 ). IR = 3106w, 2995w, 2982sh, 2945w, 287w, 2195s, 1590m, 1560w cm ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 7.69-7.67 (m, 2H), 7.40 (dd, J = 5.0, 3.1 Hz,

1 H), 6.93 (br dd, J = 5.1 , 3.1 Hz, 1 H), 6.81 (br dd, J = 5.1 , 3.2 Hz, 1 H), 4.06 (ddtd, J = 3.2, 2.4, 1.7, 0.7 Hz, 1 H), 3.91 (ddtd, J = 3.1 , 2.4, 1.7, 0.9 Hz, 2H), 2.27 (dt, J = 6.8, 1.7 Hz, 1 H), 2.18 (dt, J = 6.8, 1.7 Hz, 1 H) ppm. ¹³ C NMR (CDCIs, 100 MHz): d = 165.3, 143.4, 140.0, 135.5, 127.2, 125.9, 125.5, 118.7, 114.6, 71.1 , 54.5, 54.4 ppm. MS (ESI, +ve) = 222 ([M+Na] ⁺ ). HRMS (ESI,

+ve) calcd for C12H10NS ([M+H] ⁺ ): 200.0528; exp 200.0524.

Example 2A

2-Cyano-3-(4-nitrophenyl)quadricyclane (7a)

An argon flushed solution of 2a (280 mg) in CHCI3 (50 ml_) was subjected to 365 nm irradiation overnight. The volume was carefully reduced by rotary evaporation and the concentrate purified by flash column chromatography (CH2Cl2/n-hexane 4:1 ), to afford 7a (155 mg, 55%) as a feint yellow solid in addition to recovered 2a (120 mg). R t = 0.35 (CH2Cl2/n-hexane 7:3). IR = 3194vw, 3108w, 3081 w, 2960sh, 2936w, 2860w, 2846sh, 2220m, 1597s, 1512s, 1503sh cm ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 8.13 (d, J = 9.0 Hz, 2H),

7.30 (d, J = 9.0 Hz, 2H), 2.73 (dd, J = 4.9, 2.6 Hz, 1 H), 2.51-2.45 (m, 2H),

2.30 (dt, J = 12.1 , 1 .4 Hz, 1 H), 2.07 (dq, J = 5.0, 1 .4 Hz, 1 H) ppm. ¹³ C NMR (CDCIs, 100 MHz): d = 146.1 , 145.0, 125.8, 123.8, 1 19.0, 35.2, 34.5, 32.5, 31 .1 , 26.8, 25.0, 14.1 ppm.

Example 2B

2-Cyano-3-(3-nitrophenyl)quadricyclane (7b)

An argon flushed stirring solution of 2b (283 mg) in CHCI3 (50 ml_) was subjected to 310 nm irradiation overnight. The volume was carefully reduced by rotary evaporation and the concentrate purified by flash column

chromatography (CH2Cl2/n-hexane 1 : 1 ) to afford 7b (91 mg, 32%) as a white solid in addition to recovered 2b (188 mg). R f = 0.33 (CH2Cl2/n-hexane 7:3).

IR = 3087w, 3074sh, 2960sh, 2934w, 2863w, 2219m, 1617w, 1578w, 1526s cm ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 8.06 (dddd, J = 8.2, 2.3, 1 .1 , 0.5 Hz,

1 H), 7.91 (dd, J = 2.3, 1 .7 Hz, 1 H), 7.67 (dddd, J = 7.7, 1 .7, 1 .1 , 0.5 Hz, 1 H), 7.50 (ddt, J = 8.2, 7.7, 0.5 Hz, 1 H), 2.72 (dd, J = 4.9, 2.6 Hz, 1 H), 2.50 (dt, J = 12.0, 1 .4 Hz, 1 H), 2.46 (dq, J = 4.9, 1 .4 Hz, 2H), 2.42 (dd, J = 5.1 , 2.6 Hz,

1 H), 2.29 (dt, J = 12.0, 1 .4 Hz, 1 H), 2.03 (dq, J = 5.1 , 1 .4 Hz, 2H) ppm. ¹³ C NMR (CDCIs, 100 MHz): <5 = 148.5, 138.5, 132.6, 129.7, 121 .5, 120.7, 1 18.9, 35.3, 32.7, 32.5, 30.9, 26.8, 23.2, 14.4 ppm.

Example 2C

2-Cyano-3-(4-fluorophenyl)quadricyclane (7c)

Complete conversion was effected by irradiation of a toluene solution of 2c with 310 nm giving 7c as a colorless oil. Rf = 0.51 (CH2Cl2/n-hexane 1 :1 ). IR = 3073w, 3053w, 2957sh, 2935w, 2863w, 1608w, 1595w, 1515s cm ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 7.22-7.17 (m, 2H), 7.04-6.98 (m, 2H), 2.65 (dd, J = 4.9, 2.6 Hz, 1 H), 2.44 (dt, J = 1 1 .9, 1 .4 Hz, 1 H), 2.39 (dq, J = 4.9, 1 .4 Hz,

1 H), 2.24-2.21 (m, 2H), 1 .87 (dq, J = 5.0, 1 .4 Hz, 1 H) ppm. ¹³ C NMR (CDCIs,

100 MHz): d = 161 .8 (d, J = 245.6 Hz), 131 .5 (d, J = 3.2 Hz), 128.2 (d, J = 8.1 Hz), 119.4, 115.6 (d, J = 21.6 Hz), 35.3, 32.4, 31.3, 30.8, 26.7, 21.9, 14.6 ppm.

Example 2D

2-Cyano-3-(2-fluorophenyl)quadricyclane (7d)

Complete conversion was effected by irradiation of a toluene solution of 2d with 310 nm giving 7d as a colorless oil. Rf = 0.45 (CH2Cl2/n-hexane 1 :1 ). IR = 3067w, 2956sh, 2935w, 2862w, 2222s, 1585w, 1500s cm ¹ . ¹ H NMR

(CDCIs, 400 MHz): d = 7.30 (td, J = 7.5, 1.8 Hz, 1 H), 7.22 (dddd, J = 8.2, 7.5, 5.2, 1.8 Hz, 1 H), 7.10 (td, J = 7.5, 1.3 Hz, 1 H), 7.03 (ddd, J = 10.6, 8.2, 1.3

Hz, 1 H), 2.64 (dd, J = 4.9, 2.6 Hz, 1 H), 2.49 (dt, J = 11.9, 1.5 Hz, 1 H), 2.50- 2.37 (m, 2H), 2.25 (dt, J = 11.9, 1.5 Hz, 1 H), 1.96 (dtd, J = 4.4, 1.5, 0.8 Hz,

1 H) ppm. ¹³ C NMR (CDCIs, 100 MHz): d = 161.7 (d, J = 247.1 Hz), 129.6 (d, J = 3.9 Hz), 128.8 (d, J = 8.0 Hz), 124.2 (d, J = 3.6 Hz), 122.8 (d, J = 14.2 Hz), 119.4, 115.7 (d, J = 21.0 Hz), 35.2, 32.4 (d, J = 1.5 Hz), 30.4, 27.6 (d, J = 1.0 Hz), 26.6, 21.1 , 15.1 (d, J = 0.6 Hz) ppm.

Example 2E

2-Cyano-3-(3-fluoro-4-methoxyphenyl)quadricyclane (7e)

Complete conversion was effected by irradiation of a chloroform solution of 2e with 310 nm giving 7e as a colorless oil. Rf = 0.20 (CH2Cl2/n-hexane 3:2). IR = 3072vw, 3007vw, 2961 sh, 2936w, 2913sh, 2862w, 2843w, 2218m, 1621w,

1582w, 1520s, 1509sh cm ¹ . ¹ H NMR (CDCIs, 400 MHz): <5 = 7.02 (ddd, J = 8.4, 2.2, 1.2 Hz, 1 H), 6.94-6.86 (m, 2H), 3.87 (s, 3H), 2.63 (dd, J = 4.9, 2.6 Hz, 1 H), 2.43 (dt, J = 11.9, 1.4 Hz, 1 H), 2.38 (dq, J = 4.9, 1.4 Hz, 1 H), 2.23- 2.19 (m, 2H), 1.85 (dq, J = 5.0, 1.4 Hz, 1 H) ppm. ¹³ C NMR (CDCIs, 100 MHz): <5 = 152.4 (d, J = 246.7 Hz), 146.6 (d, J = 10.7 Hz), 128.7 (d, J = 6.8 Hz),

122.8 (d, J = 3.5 Hz), 119.3, 114.5 (d, J = 18.8 Hz), 113.7 (d, J = 2.3 Hz),

56.5, 35.3, 32.3, 31.1 , 26.7, 21.9, 14.6 ppm.

Example 2F

2-Cyano-3-(2-methoxyphenyl)quadricyclane (7f) Complete conversion was effected by irradiation of a chloroform solution of 2f with 365 nm giving 7f as a colorless oil. R f - 0.38 (ChteCh/n-hexane 3:1 ). IR = 3067vw, 3054 vw, 3002vw, 2954sh, 2934w, 2905sh, 2882vw, 2859vw, 2837w, 2200m, 1602w, 1582w cm ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 7.24 (ddd, J =

8.3, 7.4, 1 .8 Hz, 1 H), 7.07 (dd, J = 7.7, 1 .8 Hz, 1 H), 6.90-6.86 (m, 2H), 3.88 (s, 3H), 2.57 (dd, J = 4.9, 2.6 Hz, 1 H), 2.46 (dt, J = 1 1 .7, 1 .4 Hz, 1 H), 2.33 (dq, J = 4.9, 1 .4 Hz, 1 H), 2.26 (dd, J = 5.0, 2.6 Hz, 1 H), 2.20 (dt, J = 1 1 .7, 1 .4 Hz, 1 H), 1 .81 (dq, J = 5.0, 1 .4 Hz, 1 H) ppm. ¹³ C NMR (CDCIs, 100 MHz): d = 159.2, 128.8, 128.7, 123.3, 120.4, 120.1 , 1 10.6, 55.5, 35.2, 32.5, 29.8, 29.8,

26.3, 20.0, 15.6 ppm.

Example 2G

2-Cyano-3-(3-methoxyphenyl)quadricyclane (7g)

Complete conversion was effected by irradiation of a chloroform solution of 2g with 365 nm giving 7g as a colorless gummy oil. Rf = 0.33

(CH2Cl2/petroleum spirit 3:2). IR = 3067w, 3002w, 2955w, 2862w, 2836w, 2218s, 1608sh, 1602s, 1589sh, 1580s cm ¹ . ¹ H NMR (CDCIs, 400 MHz): <5 = 7.27-7.22 (m, 1 H), 6.81-6.76 (m, 3H), 3.82 (s, 3H), 2.66 (dd, J = 5.0, 2.6 Hz,

1 H), 2.45 (dt, J = 1 1 .9, 1 .4 Hz, 1 H), 2.40 (dq, J = 5.0, 1 .4 Hz, 1 H), 2.28 (dd, J = 5.0, 2.6 Hz, 1 H), 2.24 (dt, J = 1 1 .9, 1 .4 Hz, 1 H), 1 .92 (dq, J = 5.0, 1 .4 Hz,

1 H) ppm. ¹³ C NMR (CDCIs, 100 MHz): <5 = 159.9, 137.7, 129.7, 1 19.6, 1 18.2,

1 12.3, 1 1 1 .6, 55.4, 35.4, 32.4, 32.1 , 31 .3, 26.8, 22.5, 14.3 ppm.

Example 2H

2-Cyano-3-(3,4-dimethoxyphenyl)quadricyclane (7h)

Complete conversion was effected by irradiation of a toluene solution of 2h with 365 nm giving 7h as a colorless oil. R t - 0.26 (CH2CI2). IR = 3073vw, 3000w, 2957sh, 2935w, 291 Osh, 2860vw, 2836w, 2217m, 1607w, 1587w, 1519s, 1509sh cm ¹ . ¹ H NMR (CDCIs, 400 MHz): <5 = 6.81 (d, J = 8.2 Hz, 1 H), 6.80 (d, J = 2.1 Hz, 1 H), 6.74 (dd, J = 8.2, 2.1 Hz, 1 H), 3.89 (s, 3H), 3.86 (s, 3H), 2.63 (dd, J = 4.9, 2.6 Hz, 1 H), 2.44 (dt, J = 1 1 .8, 1 .4 Hz, 1 H), 2.37 (dq, J = 4.9, 1 .4 Hz, 1 H), 2.23-2.19 (m, 2H), 1 .87 (dq, J = 5.1 , 1 .4 Hz, 1 H) ppm. ¹³ C NMR (CDCI ₃ , 100 MHZ): d = 149.1 , 148.0, 128.2, 119.7, 118.7, 111.5, 110.1 , 56.1 , 56.0, 35.3, 32.4, 31.3, 30.8, 26.7, 21.8, 14.6 ppm.

Example 2I

2-Cyano-3-(2,4-dimethoxyphenyl)quadricyclane (7i)

Complete conversion was effected by irradiation of a chloroform solution of 2i with 365 nm giving 7i as a colorless oil. R f - 0.39 (EtOAc/n-hexane 1 :4). IR = 3076vw, 3052vw, 2958sh, 2935w, 2907sh, 2859vw, 2838w, 2220m, 1613s, 1583m, 1512s cm ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 6.97 (d, J = 8.3 Hz, 1 H), 6.47 (d, J = 2.4 Hz, 1 H), 6.40 (dd, J = 8.3, 2.4 Hz, 1 H), 3.87 (s, 3H), 3.79 (s, 3H), 2.55 (dd, J = 4.9, 2.5 Hz, 1 H), 2.44 (dt, J = 11.6, 1.4 Hz, 1 H), 2.30 (dq, J = 4.9, 1.4 Hz, 1 H), 2.19-2.15 (m, 2H), 1.74 (dq, J = 4.9, 1.4 Hz, 1 H) ppm. ¹³ C NMR (CDCIs, 100 MHz): d = 160.6, 160.4, 129.7, 120.1 , 115.6, 104.0, 98.8, 55.6, 35.2, 32.4, 29.2, 29.2, 26.2, 19.6, 15.7 ppm.

Example 2J

2-Cyano-3-(3,4,5-trimethoxyphenyl)quadricyclane (7j)

Complete conversion was effected by irradiation of a chloroform solution of 2j with 365 nm giving 7j as a colorless oil. Rf = 0.14 (CH2CI2). IR = 3073vw, 2997w, 2961 sh, 2937w, 2830w, 2217m, 1602sh, 1583s, 1573sh, 1510m, 1503sh cm ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 6.43 (s, 2H), 3.86 (s, 6H), 3.82 (s, 3H), 2.65 (dd, J = 4.9, 2.6 Hz, 1 H), 2.45 (dt, J = 11.9, 1.4 Hz, 1 H), 2.39 (dq, J = 4.9, 1.4 Hz, 1 H), 2.25-2.21 (m, 2H), 1.90 (dq, J = 5.0, 1.4 Hz, 1 H) ppm. ¹³ C NMR (CDCIs, 100 MHz): d = 153.5, 136.8, 131.6, 119.6, 103.3,

61.0, 56.3, 35.4, 32.4, 31.7, 31.5, 26.7, 22.3, 14.5 ppm.

Example 2K

2-Cyano-3-(3,4-methylenedioxyphenyl)quadricyclane (7k)

Complete conversion was effected by irradiation of a chloroform solution of 2k with 365 nm giving 7k as a colorless oil. Rf = 0.33 (CH2Cl2/n-hexane 7:3). IR = 3074vw, 2933w, 2892w, 2863w, 2779vw, 2218m, 1608w, 1505s, 1496sh cm ¹ . ¹ H NMR (CDCIs, 400 MHz): <5 = 76.76 (dd, J = 8.0, 0.5 Hz, 1 H), 6.73 (dd, J = 8.0, 1 .7 Hz, 1 H), 6.68 (dd, J = 1 .7, 0.5 Hz, 1 H), 5.93 (s, 2H), 2.62 (dd, J = 4.9, 2.6 Hz, 1 H), 2.42 (dt, J = 1 1 .9, 1 .4 Hz, 1 H), 2.36 (dq, J = 4.9, 1 .4 Hz,

1 H), 2.22-2.17 (m, 2H), 1 .81 (dq, J = 5.0, 1 .4 Hz, 1 H) ppm. ¹³ C NMR (CDCIs, 100 MHz): <5 = 147.9, 146.7, 129.2, 120.3, 1 19.5, 108.5, 107.4, 101 .2, 35.4, 32.3, 31 .4, 31 .0, 26.7, 21 .6, 14.8 ppm.

Example 2L

2-Cyano-3-(1 -naphthyl)quadricyclane (7I)

Complete conversion was effected by irradiation of a chloroform solution of 2I with 365 nm giving 7I as a colorless oil. R f - 0.32 (CH2Cl2/n-hexane 1 :1 ). IR = 3094sh, 3065sh, 3049w, 3013vw, 2953sh, 2933w, 2861 w, 2219m, 1593w, 1580sh, 1509w cm ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 7.96 (ddt, J = 8.3, 1 .4, 0.7 Hz, 1 H), 7.88 (ddt, J = 8.1 , 1 .4, 0.7 Hz, 1 H), 7.81 (ddt, J = 8.0, 1 .5, 0.7 Hz, 1 H), 7.59 (ddd, J = 8.3, 6.9, 1 .4 Hz, 1 H), 7.53 (ddd, J = 8.1 , 6.9, 1 .4 Hz, 1 H),

7.42 (dd, J = 8.0, 7.0 Hz, 1 H), 7.37 (dd, J = 7.0, 1 .5 Hz, 1 H), 2.77 (dd, J = 4.9, 2.6 Hz, 1 H), 2.73 (dt, J = 12.1 , 1 .4 Hz, 1 H), 2.51 (dq, J = 4.9, 1 .4 Hz, 1 H),

2.43 (dd, J = 5.0, 2.6 Hz, 1 H), 2.39 (dt, J = 12.1 , 1 .4 Hz, 1 H), 1 .85 (dq, J =

5.0, 1 .4 Hz, 1 H) ppm. ¹³ C NMR (CDCIs, 100 MHz): d = 133.9, 133.3, 130.8, 128.9, 128.7, 127.2, 126.5, 126.2, 125.4, 124.8, 1 19.2, 35.9, 32.8, 31 .3, 30.4, 26.7, 19.2, 16.6 ppm.

Example 2M

2-Cyano-3-(2-naphthyl)quadricyclane (7m)

Complete conversion was effected by irradiation of a chloroform solution of 2m with 365 nm giving 7m as a colorless oil. Rf = 0.35 (CH2Cl2/n-hexane 1 :1 ). IR = 3084sh, 3054w, 3024w, 2958sh, 2931 w, 2859w, 2217s, 1630m, 1601 m,

1574w, 1507w cm ¹ . ¹ H NMR (CDCIs, 400 MHz): <5 = 7.82-7.76 (m, 4H), 7.50- 7.42 (m, 2H), 7.24 (dd, J = 8.5, 1 .8 Hz, 1 H), 2.69 (dd, J = 4.9, 2.6 Hz, 1 H),

2.50 (dt, J = 1 1 .9, 1 .5 Hz, 1 H), 2.43 (dq, J = 4.9, 1 .5 Hz, 1 H), 2.37 (dd, J =

5.0, 2.6 Hz, 1 H), 2.27 (dt, J = 1 1 .9, 1 .5 Hz, 1 H), 2.00 (dq, J = 5.0, 1 .5 Hz, 1 H) ppm. ¹³ C NMR (CDCIs, 100 MHz): <5 = 133.5, 133.4, 132.2, 128.4, 127.8, 127.6, 126.5, 125.8, 124.8, 124.1 , 119.7, 35.4, 32.5, 32.0, 31.5, 26.8, 22.4,

14.4 ppm.

Example 2N

2-Cyano-3-(4-(/V,/V-dimethylamino)phenyl)quadricyclane (7n)

Complete conversion was effected by irradiation of a toluene solution of 2n with 365 nm giving 7n. Concentration gave a consistent mixture, which were used for DSC. Rf = 0.32 (toluene). ¹ H NMR (toluen e-ds, 400 MHz): d = 7.13 (d, J = 8.9 Hz, 2H), 6.50 (d, J = 8.9 Hz, 2H), 2.52 (s, 6H), 1.89 (dt, J = 11.6,

1.4 Hz, 1 H), 1.87 (dd, J = 4.9, 2.6 Hz, 1 H), 1.67 (dq, J = 4.9, 1.5 Hz, 1 H),

1.64-1.61 (m, 2H), 1.37 (dq, J = 4.9, 1.5 Hz, 1 H) ppm. ¹³ C NMR (toluene-cfe, 100 MHz): <5 = 149.8, 137.4, 123.3, 119.0, 112.9, 40.1 , 34.7, 32.0, 31.3, 30.1 , 25.8, 21.3, 15.1 ppm.

Example 20

2-Cyano-3-(4-(ferf-butylthio)phenyl)quadricyclane (7o)

Complete conversion was effected by irradiation of a toluene solution of 2o with 365 nm giving 7o as a colorless oil. R f - 0.28 (CH2Cl2/n-hexane 1 :1 ). IR = 3073w, 3059w, 3031 w, 2969sh, 2961 m, 2939m, 2925sh, 2897m, 2862m, 2220s, 1598m - ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 7.46 (d, J = 8.1 Hz, 2H),

7.16 (d, J = 8.1 Hz, 2H), 2.66 (dd, J = 4.8, 2.6 Hz, 1 H), 2.45 (dt, J = 12.0, 1.4 Hz, 1 H), 2.40 (dq, J = 4.8, 1.4 Hz, 1 H), 2.30 (dd, J = 5.0, 2.6 Hz, 1 H), 2.24 (dt, J = 11.9, 1.4 Hz, 1 H), 1.94 (dq, J = 5.0, 1.4 Hz, 1 H), 1.27 (s, 9H) ppm. ¹³ C NMR (CDCIs, 100 MHz): d = 137.7, 137.1 , 130.6, 125.8, 119.6, 46.1 , 35.4, 32.5, 32.4, 31.0, 31.0, 26.8, 23.0, 14.1 ppm.

Example 2P

2-Cyano-3-(2-thiophenyl)quadricyclane (7p)

Complete conversion was effected by irradiation of a chloroform solution of 2p with 365 nm giving 7p as a colorless oil. Rf = 0.28 (CH2Cl2/n-hexane 1 :1 ). IR = 3105w, 3075w, 3056sh, 2955sh, 2935w, 2861w, 2220s, 1538 cm ¹ . ¹ H NMR (CDCIs, 400 MHz): 5 = 7.16 (dd, J = 5.1 , 1.2 Hz, 1 H), 7.09 (dd, J = 3.5, 1.2 Hz, 1 H), 6.97 (dd, J = 5.1 , 3.5 Hz, 2H), 2.66 (dd, J = 4.9, 2.6 Hz, 1 H), 2.47 (dt, J = 11.9, 1.4 Hz, 1 H), 2.39 (dq, J = 4.9, 1.4 Hz, 1 H), 2.26-2.21 (m, 2H), 2.02 (dq, J = 5.0, 1.4 Hz, 1 H) ppm. ¹³ C NMR (CDCIs, 100 MHz): d = 138.8, 127.5, 125.8, 124.3, 118.9, 35.1 , 32.3, 31.6, 27.3, 26.6, 24.5, 15.9 ppm.

Example 2Q

2-Cyano-3-(3-thiophenyl)quadricyclane (7q)

Complete conversion was effected by irradiation of a chloroform solution of 2q with 365 nm giving 7p as a colorless oil. R f - 0.36 (CH2Cl2/n-hexane 1 :1 ). IR = 3104w, 3059sh, 2952sh, 2933w, 2860w, 2219s, 1542w cm ¹ . ¹ H NMR (CDCIs, 400 MHz): d = 7.29 (dd, J = 5.0, 2.9 Hz, 1 H), 7.23 (dd, J = 2.9, 1.3 Hz, 1 H), 6.86 (dd, J = 5.0, 1.3 Hz, 1 H), 2.63 (dd, J = 5.0, 2.6 Hz, 1 H), 2.43 (dt, J = 11.8, 1.4 Hz, 2H), 2.37 (dq, J = 5.0, 1.4 Hz, 1 H), 2.22 (dt, J = 11.8, 1.4 Hz, 1 H), 2.17 (dd, J = 4.9, 2.6 Hz, 1 H), 1.96 (dq, J = 4.9, 1.4 Hz, 1 H) ppm. ¹³ C NMR (CDCIs, 100 MHz): d = 136.6, 126.2, 125.8, 120.2, 119.7, 35.1 , 32.3, 30.7, 28.0, 26.7, 22.9, 14.3 ppm.

Test of Photophysical properties

The compounds as synthesized according to the Examples above were tested regarding their Photophysical Properties. The first was assessment of the properties of the compounds was centered on the absorbance profiles, both maxima and onset, for each NBD-QC couples 2a-q/7a-q, which can be seen in Table 1. These measurements were made in toluene as it is thought that this non-halogenated high boiling solvent was practical choice for future devices involving these types of derivatives as well as it allows for direct comparison with our recent reports (refs). In these cases, corresponding QCs 7a-q were generated in situ, using a selection of wavelengths, 310 nm, 340 nm or 365 nm. In the cases of NBDs 2a and 2b, photostationary states were obtained in toluene upon exposure to 365 nm and 310 nm light source respectively, which was substantiated by ¹ H NMR. Instead, in these

instances, the absorbance values for these QCs were measured from the material isolated by column chromatography. NBD

2a 337 (10.9) 401 20

2b 302 (7.1) 381 19

2c 308 (8.3) 359 49

2d 301 (6.9) 350 50

2e 325 (13.0) 377 40

2f 322 (6.5) 368 70

2g 315 (8.3) 365 60

2h 340 (14.2) 389 68

2i 330 (10.6) 385 73

2j 331 (12.5) 384 68

2k 338 (12.0) 383 82

21 321 (7.6) 373 59

2m 326 (15.6) 384 60

2n 374 (23.3) 427 73

2o 324 (12.2) 380 55

2p 336 (11.0) 390 61

2q 312 (9.4) 367 60

Table 1. Absorbance properties of NBDs 2a-q. It was found that the quantum yields for the nitro-substituted NBDs 2a and 2b were rather low compared to all the other derivatives. Compound 2n exhibited the furthest red shifting in the UV-vis spectrum, complemented with a very large extinction coefficient, however only a small part of the spectrum was not conflicted by absorbance of corresponding QC 7n. In contrast, using the methoxy donating group, in different combinations and even in multiple substitution patterns, showed only small variation in absorbance maxima and quantum yields, but in many instances, there were large differences between the onsets of absorption for the NBDs relative to the corresponding QCs. The highest measured quantum yield of 82% was recorded for the methylenedioxy substituted derivative 2k, which otherwise shared similar properties to the other methoxy substituted NBDs. An increasing trend for the quantum yield had been previously reported for NBD derivatives bearing an arylketone in the 2-position conjugated to an aromatic ring in the 3-position. In that case, the placement of increasing electron withdrawing substituents on the aryl ketone increased quantum yields for QC formation^ No clear trend could be seen in this study aside from the fact that electron rich aryl substituents generally gave better results. The use of naphthalene substituents, 21 and 2m, didn’t seem to add any significant enhancement to the spectroscopic properties. Placement of a fluorine substituent in either the 2- or 4-position, 2c and 2d respectively, did very little to alter the spectroscopic properties compared with parent compound 2.

The kinetic stabilities of QCs 7a-q were determined by monitoring the decay in toluene at three different temperatures. Table 2 includes the half-lives calculated for all the QCs, in addition to the Arrhenius pre-exponential factor.

QC E _a (kJ mol ¹ ) A k ₂₅ (s ¹ ) t½ 25 °C

(days)

7a 104 1.54 xlO ¹² 1.04 xlO ⁶ 7.74

7b 120 7.36 xlO ¹³ 7.38 xlO ⁸ 108.7

7c 119 6.54 xlO ¹³ 8.93 xlO ⁸ 89.8

7d 183 3.25 xlO ²³ 2.99 x 10 ⁹ 2680

7e 114 2.08 xlO ¹³ 2.41 xlO ⁷ 33.3

7f 137 3.96 xlO ¹⁵ 3.53 xlO ⁹ 2273

7 119 7.72 xlO ¹³ 1.03 xlO ⁷ 78

7h 119 1.91 xlO ¹⁴ 2.79 xlO ⁷ 28.7

7i 142 2.32 xlO ¹⁶ 2.70 x 10 ⁹ 2971

7j 112 1.28 xlO ¹² 3.31 xlO ⁷ 24.2

7k 109 5.49 xlO ¹³ 4.11 xlO ⁶ 1.95

71 144 2.32 xlO ¹⁶ 1.19 x 10 ⁹ 6729

7m 169 1.30 xlO ²² 3.79 xlO ⁸ 212

7n 114 1.06 xlO ¹⁴ 1.14 x 10 ⁶ 7.04

7o 117 8.33 xlO ¹³ 2.81 x 10 ⁷ 28.5

7p 98 4.94 xlO ¹² 3.59 xlO ⁵ 0.22

7q 111 8.27 xlO ¹² 3.54 x 10 ⁷ 22.7

Table 2. Kinetic data for the thermal back conversions of 7a-q to 2a-q

The most notable data was the kinetic stabilities measured for QCs 7d, 7f, 7i and 71, which had half-lives well exceeding a year. All these derivatives shared a common feature, in that a substituent protruded from the ortho position, which indeed could, on the account such a constrained transition state may interfere sterically with the rate of the retro [2+2TT] reaction. In fact the Arrhenius values determined from the kinetic decay for all these systems were exceedingly high, possibly a reflection of the importance of the alignment of the aryl substituents in the transition state in these sterically challenged derivatives. Nevertheless, in terms of MOST, this trend in data is extremely useful in the context of long term energy storage and demonstrates that it is possible to effectively delineate the normal correlation between increased onset of absortion accompanied by reduced thermal stability. On the other hand, 7k, for which the corresponding NBD 2k exhibited the highest quantum yield had a half-life of only 2 days. The QC with a 2-thiophene substituent 7p, a donor calculated to enhance MOST properties, exhibited an exceedingly high rate of ring opening. However, the half-life could be protracted to nearly a month when the thiophene was attached through the 3-position (compound 7q).

The pair of compounds, NBD/QC 2d/7d, 2f/7f, 2i/7i, 2I/7I do all feature room temperature halft lives well on order of years and/or back-conversion barriers exceeding 130 kJ/mol. In addition, the compound pairs NBD/QC 2d/7d, 2f/7f, 2i/7i, 2I/7I feature strongly red-shift absorption spectra with a good solar spectrum match. Thus, they surprisingly differ from previously known NBD/QC compounds, when comparing the first absorption maximum and the back- conversion barrier.

While the invention has been described in connection with what is presently considered to be the most practical embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, it is intended to cover various modifications and equivalents included within the spirit and scope of the appended claims.

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