Catalyst for alkyne metathesis

The present invention relates to catalysts suitable for alkyne metathesis, to the use of catalysts in alkyne metathesis and to processes in the presence of the catalysts, e.g. synthesis or metathesis processes. The catalysts comprise a ligand, on his part containing a nitrogen which is forming a complex with a transition metal atom

Catalysts of the invention contain a metal atom which is coordinated by two alkoxy groups and one anionic electron donating ligand comprising a nitrogen atom. In the catalytically active form, the metal atom is bound to a substituted carbon by a triple bond. In use as alkyne metathesis catalysts, the compounds of the invention mediate transfer of the substituted carbon by formal transfer to or exchange with another carbon atom being linked by a triple bond, i.e. an alkyne, while maintaining the triple bond.

State of the art

Tamm (Chem. Commun. 2004, 876-877) disclose the synthesis of titanium complexes having imidazolin-2-iminato ligands.

In Tamm et al. (Org. Biomol. Chem. 2007, 5, 523-530), the structure of 2-iminoimidazoline compounds is described.

Tamm et al. (Dalton Trans. 2006, 459-467) describe the synthesis of imidazolin-2-iminato titanium complexes and their use in ethylene polymerization catalysis.

Fϋrstner et al. (Chem. Commun. 2005, 2307-2320) describe alkyne metathesis using a molybdenum tris-amido complex.

When reviewing the metathesis catalysts for the conversion of alkenes and alkynes, Schrock et al. (Adv. Synth. Cat. 2007, 349, 55-77) describe molybdenum or tungsten tris-amido or tris- alkoxy compounds for use in metathesis catalysis of alkynes.

Fϋrstner in Angew. Chem. 2000, 112, 3140-3172, reviews tungsten and molybdenum alkylidene complexes and ruthenium carbene complexes as catalysts for olefin metathesis.

US 2006/0281938 Al describes alkyne metathesis using a tris-amido metal complex.

Stoner et al. in J. Am. Chem. Soc. 112, 5651-5653 (1990) describe conjugated transition metal complexes M ₂ (CCR) ₄ (PMeS) ₄ comprising an alkynyl ligand and a trimethylphosphine ligand in each complex.

WO 99/40047 describes catalysts of the general type M (≡CRl) (OR2) ₃ , wherein Rl can be alkyl, aryl, alkenyl, alkylthio, dialkylamino, and R2 can be e.g. alkyl, aryl, fluorine alkyl. Further, catalysts can be mixtures Of M[N(Rl)Ar] ₃ with halogen compounds of the type R2 ₂ EX ₂ or R3 ₃ SiX with E = C or Si, X = halogen, and R3 = alkyl or aryl.

One disadvantage of catalytically active tris-amido molybdenum complexes, e.g. according to Fϋrstner et al. (Chem. Eur. J. 2001, 7, 5299-5317) or from WO 99/40047, is that these require

a temperature of above 80 ⁰ C and catalyst concentrations of more than 5 to 10 mol-% for a moderate catalytic activity. Further, the known catalysts for alkyne metathesis are unstable as they are sensitive towards inactivation by oxidation or hydrolysis.

Objects of the invention

In view of the known catalysts and processes for alkyne metathesis, it is an object of the present invention to provide compounds having an alternative structure for use as catalysts in alkyne metathesis and metathesis processes involving the use of the catalytically active compounds. Preferably, the compounds have a structure allowing a high efficiency of the metathesis reaction, preferably allowing metathesis reactions to occur at lower temperatures.

General description of the invention

The above objects of the invention are attained by the catalytically active compounds of the invention, which comprise a nitrogen ligand that on his part is forming a complex with a transition metal atom. Formally, the nitrogen containing ligand is formally anionic or mononegative and binds with the metal atom. The monoanionic nitrogen ligand can be embodied as an imine or an amine, preferably as a guanidinato group, a phosphoraniminato group or a disubstituted amine group. One or both of the nitrogen atoms of the guanidinate core the phosphate atom of the phosphoraniminato group, or the substituents to the amine group, which are not participating in the metal complexing bond, can be substituted with substituents being selected from hydrogen, alkyl, alkenyl, aromatic residues, optionally including hetero atoms, e.g. halogen atoms, preferably fluorine.

Further, substituents to the nitrogen atoms not participating in the metal complexing bond can be linked to the metal complexing nitrogen atom by at least one single (C-C) or double (C=C) bond.

Preferably, the valences of the nitrogen atom of the nitrogen ligand which do not complex the transition metal form a double bond, e.g. with the carbon atom of the guanidinato group, or with the phosphor atom of the phosphoraniminato group.

In embodiments of the nitrogen ligand in the form of a phosphoraniminato group, the phosphor atom is preferably substituted with three different or identical moieties, e.g. selected from hydrogen, alkyl, alkenyl and aromatic residues.

In embodiments of the nitrogen ligand in the form of an amine group, the nitrogen in addition to the metal complexing bond is preferably substituted with two different or identical moieties, e.g. selected from hydrogen, alkyl, alkenyl, aromatic residues, optionally including hetero atoms, e.g. halogen atoms, preferably fluorine.

In embodiments of the nitrogen ligand in the form of a guanidinato group, both the nitrogen atoms which are bound to the nitrogen atom complexing the transition metal atom are preferably substituted with different or identical moieties, e.g. selected from hydrogen, alkyl, alkenyl and aromatic residues, which residues optionally bind to both carbon atoms linked to the carbon atom of the guanidinato group, e.g. selected from CH ₂ -CH ₂ , C(H)=C(H), and C(Me)=(CMe).

In addition to the mononegative nitrogen ligand, the metal atom is complexed by two identical or different alkoxy or aryloxy groups, optionally substituted with halogen.

The catalytically active complex exhibits a carbon-metal triple bond, which is essential for alkyne metathesis reactions. The substituents to this carbon atom can be derivatized any way by any substituent moiety because this ligand moiety will be demerged during the metathesis reaction, and therefore does not initially participate in the alkyne metathesis.

The catalytically active compounds of the invention correspond to formula I:

(I)

wherein Zl and Z2 independently are substituents to the nitrogen atom complexing the transition metal atom. Zl and Z2 can be substituents forming an amine group of the nitrogen complexing the metal atom, preferably Zl and Z2 are one substituent linked to the nitrogen complexing the metal atom by a double bond, e.g. forming a guanidinato group or a phosphoraniminato group. M is a transition metal, preferably Mo or W.

Preferably, Zl and Z2 are a group forming an imine including the nitrogen atom complexing the metal atom, e.g. an imine forming a guanidinato group or a phosphoraniminato group.

In a first embodiment, Zl and Z2 and the nitrogen atom complexing the metal atom form a guanidinato ligand according to formula II:

(H)

wherein M is Mo or W,

R ¹ , R ² are independently selected from hydrogen, Cl to C20 alkyl or aryl, optionally containing heteroatoms e.g. N, O, and/or S, preferentially methyl (Me), isopropyl (CHMe ₂ ), tert.-butyl (CMe ₃ ), and aryl, preferentially 2,4,6-Me ₃ -C ₆ H ₂ , and 2,6-/Pr ₂ -C ₆ H ₃ , wherein zPr is isopropyl and C ₆ H ₃ is phenyl,

R ³ , R ⁴ are selected from Cl to C20 alkyl or aryl, optionally containing heteroatoms, e.g. N, O, and/or S, preferentially CMe ₃ , CH(CF ₃ ) ₂ , CMe ₂ CF ₃ , CMe(CF ₃ ) ₂ , C(CF ₃ ) ₃ , and aryl, preferentially 2 ,4,6-(CF ₃ )-C ₆ H ₂ , and 2,6-(CF ₃ )-C ₆ H ₃ , wherein C ₆ H ₃ is phenyl,

X ¹ , X ² are independently selected from H, Cl to C20 alkyl or aryl, preferentially both X ¹ and

X ² are CH ₂ -CH ₂ , C(H)=C(H), or C(Me)=C(Me),

Y is selected from Cl to C20 alkyl and aryl, preferentially CMe ₃ or phenyl (Ph).

One or both of X ¹ and R ¹ , and of X ² and R ² , respectively, can be linked, forming one common substituent to both the nitrogen atoms that do not participate in the complexing of the metal atom. For example, X ¹ and X ² can be replaced by a group comprising two, three or four atoms in a row, forming a 5-membered, a 6-membered or a 7-membered ring including the nitrogen atoms of the guanidinate core that do not participate in complexing the metal. Examples for groups replacing X ¹ and X ² are C-C, C=C, C-C-C, and C=C-C with each C substituted by one hydrogen, a halogen, or a (hetero-) alkyl.

Alternatively, X ¹ and X ² are carbon atoms being linked by single or double bond, an intermediate atom or a group of two atoms, e.g. the intermediate atom or group is selected from -CR ¹ -, -CR ¹ ₂ -CR ^! ₂ -, and -CR^CR ¹ -, with each R ¹ independently defined as above, preferably -CH=CH-, -C(CH ₃ )=C(CH ₃ ) -.

Preferably, X ¹ and X ² in formula II are replaced by C=C with each C substituted by one hydrogen, a halogen, or a (hetero-) alkyl forming an optionally further substituted 2- imidazolyl substituent to the nitrogen atom that complexes the metal atom. As a result, the following structure Ha is obtained:

(Ma)

wherein R ¹ and R ² preferably are selected independently from electron donating groups, e. tert. -butyl, and wherein

R ³ and R ⁴ can each be selected independently from hydrogen, Cl to C20 (hetero-) alkyl or (hetero-) aryl, preferably CMe ₃ , CH(CF ₃ ) ₂ , CMe ₂ CF ₃ , CMe(CF ₃ ) ₂ , and C(CF ₃ ) ₃ , and R ⁸ and R ⁹ can each be selected independently from hydrogen, Cl to C20 (hetero-) alkyl or (hetero-) aryl, preferably CMe ₃ , CH(CF ₃ ) ₂ , CMe ₂ CF ₃ , CMe(CF ₃ ) ₂ , and C(CF ₃ ) ₃ .

In a second embodiment, Zl and Z2 and the nitrogen atom complexing the metal atom form a phosphoraniminato ligand according to formula III:

(III)

wherein substituents are as given for formula II, and each R ⁵ is independently selected from hydrogen, Cl to C20 alkyl, preferentially Me, and

C ₆ Hn (cyclohexyl), or aryl, preferentially phenyl.

In a third embodiment, Zl and Z2 form an amine group of the nitrogen ligand according to formula IV:

(IV)

wherein substituents are as given for formula III, and

R ⁶ , R ⁷ are independently selected from Cl to C20 alkyl or aryl, preferentially R ⁶ = CMe ₃ , and R ⁷ = aryl, e.g. phenyl or 3,5-Me ₂ -C ₆ H ₃ .

In the catalytic processes, the compounds of the invention show the advantage that they catalyze alkyne metathesis reactions more efficiently, e.g. at lower temperatures than known catalysts, e.g. than tris-amido molybdenum complexes. Therefore, the catalysts of the invention are advantageous in use for synthetic reactions of temperature sensitive compounds.

The catalytically active compounds of the invention are advantageous in that they do not require an inert gas atmosphere during the catalysis reaction, but can be used at ambient, preferably at reduced pressure, e.g. in the range of 10 to 500 mbar. Further, the catalytic activities of the compounds of the invention are higher than those of prior art alkyne metathesis catalysts. Accordingly, the catalysts of the invention can be used at lower temperatures, e.g. in the range of 10 to 100 ⁰ C and/or at lower concentrations than previous catalysts.

In general, compounds used as catalysts in the present invention can be synthesized according to the methods described in Tamm et al., Dalton Trans. 2006, 459-467, preferably with replacement of titanium with molybdenum or tungsten.

Detailed description of the invention

The invention is now described in greater detail by way of examples.

Example 1 : Synthesis of catalyst

First, l,3-di-ter£.-butylimino-2-imidazoline lithium (ImN)Li was synthesized by dissolving l,3-di-ter£.-butylimidazoline-2-imine (718 mg, 3.68 mmol) in 45 mL hexane in a 100 mL Schlenk tube and cooling to -30 ⁰ C. Over a period of 5 min, 2.1 mL of a hexane solution of methyllithium (1.6M, 3.4 mmol) was added and stirred for 2 h allowing the solution to warm to 0 ⁰ C. The resulting white suspension was filtered through a Schlenk frit, and the residue was washed 5 times with 10 mL of hexane. The remaining white powder was dried for 5 h at high vacuum to yield 762 mg (97 %) of pure product. ¹ H NMR (200 MHz, C ₆ D ₆ , 25 ⁰ C): δ 1.58 (18 H, s, C(CHs) ₃ ), 6.11 (2 η, s, CH); ¹³ C NMR (150.9 MHz, C ₆ D ₆ , 25 ⁰ C): δ 30.6 (3 C,

s, C(CHs) ₃ ), 53.1 (2 C, s, NCMe ₃ ), 106.6 (2 C, s, NCH), 141.1 (1 C, s, NCN); Found for CnH ₂₀ N ₃ Li: C 65.2 %, H 10.3 %, N 19.8 %; Calculated: C 65.6 %, H 10.0 %, N 20.9 %.

The intermediary product corresponds to

A toluene solution of (ImN)Li (190 mg, 0.944 mmol) was slowly added to the tungsten alkylidyne complex (Me ₃ CC≡W[OCMe(CF ₃ ) ₂ ] ₃ (dme)} (837 mg, 0.944 mmol), which was dissolved in a 100 mL Schlenk tube in 25 mL toluene and stirred for 10 min at room temperature. The yellow-orange suspension was filtered through an Schlenk frit to remove any by-products. Evaporation of the solvent gave the clean product as yellow crystalline powder. Single crystals could be obtained by cooling a saturated diisopropylether solution to -35 ⁰ C. Yield: 726 mg of yellow crystals (95%). ¹ H NMR (400 MHz, C ₆ D ₆ , 25 ⁰ C): δ 1.15 (9 H, s, W≡CCCH ₃ ), 1.29 (18 H, s, NCCH ₃ ), 1.96 (6 H, br, C(CH ₃ )(CF ₃ ) ₂ ), 5.94 (2 η, s, CH); ¹³ C NMR (150.9 MHz, C ₆ D ₆ , 25 ⁰ C): δ 20.5 (2 C, s, OCCH ₃ ), 28.7 (6C, s, NCCH ₃ ), 33.8 (3 C, s, CCCH ₃ ), 50.8 ( ² JCw = 38 Hz, 1 C, OCCH ₃ ), 51.7 (2 C, s, NCCH ₃ ), 81.7 (2 C, m, OCCF ₃ ), 110.0 (2 C, s, NC=CN), 124.1 ( ¹ JcF = 287 Hz, 2 C, q, CF ₃ ), 124.8 ( ¹ JcF = 287 Hz, 2 C, q, CF ₃ ), 159.4 (1 C, s, NCN), 285.6 ( ¹ JCw = 274 Hz, 1 C, s, W≡Q; ¹⁹ F NMR (376.5 MHz, C ₆ D ₆ , 25 ⁰ C): δ -78.6 ( ⁴ J _FF = 19 Hz, 6 F, q, CF ₃ ), -76.4 ( ⁴ J _FF = 19 Hz, 6 F, q, CF ₃ ); Found for C ₂₄ H ₃₅ N ₃ Fi ₂ O ₂ W: C 36.6 %, H 4.7 %, N 5.2 %; Calculated C 35.6 %, H 4.4 %, N 5.2 %. From the data, the following structure of the catalyst was deduced:

The alternative molybdenum-containing catalyst was synthesized using the respective molybdenum alkylidyne complex in the place of the tungsten alkylidyne complex.

Example 2: Synthesis of catalyst

As described in Example 1, l,3-di-ter£.-butylimino-2-imidazoline lithium (ImN)Li was synthesized, and a toluene solution of (ImN)Li (173 mg, 0.860 mmol) was slowly added to the tungsten alkylidyne complex [Me3CC≡W(OCMe3)3] (400 mg, 0.847 mmol), which was dissolved in a 100 mL Schlenk tube in 33 mL toluene and stirred for 120 min at room temperature. The yellow-orange suspension was filtered through an Schlenk frit to remove any by-products. Evaporation of the solvent and extraction with hexane gave the pure product as yellow crystalline powder. Single crystals could be obtained by cooling a saturated diisopropylether solution to -35 ⁰ C. Yield: 488 mg of yellow crystals (97%). ¹ H NMR (400.1 MHz, C ₆ D ₆ , 25 ⁰ C): δ 1.43 (18 H, s, NC(CHs) ₃ ), 1.44 (9 H, s, W≡CC(CH ₃ ) ₃ ), 1.66 (18 η, s, OC(CHs) ₃ ), 6.03 (2 η, s, CH); ¹³ C NMR (150.9 MHz, C ₆ D ₆ , 25 ⁰ C): δ 29.1 (6 C, s, NC(CHs) ₃ ), 33.5 (6C, s, OCCH ₃ ), 34.6 (3 C, s, CC(CH ₃ ) ₃ ), 50.9 (1 C, s, CC|CH ₃ ) ₃ ), 55.9 (2 C, s, NCCH ₃ ), 77.5 (2 C, s, OCCH ₃ ), 108.5 (2 C, s, NC=CN), 159.1 (1 C, s, NCN), 273.3 ( ¹ JCw = 279 Hz, 1 C, s, W≡Q; Found for C ₂₄ H ₄₇ N ₃ O ₂ W: C 47.8%, H 7.9%, N 6.3%; Calculated C 48.6%, H 8.0%, N 7.1%.

From the analytical results, the following structure of the catalyst was deduced:

Example 3 : Synthesis of catalyst

l,3-Di-iso-propyl-4,5-dimethylimidazoline-2-imine (Im ² PrN) (1.689 g, 6.314 mmol) was dissolved in 20 mL hexane in a 100 mL Schlenk tube and cooled to -30 ⁰ C. Over a period of 10 min, 3.95 mL of a hexane solution of n-butyllithium (1.6M, 6.31 mmol) was added and stirred for 2 h allowing the solution to warm to 0 ⁰ C. The resulting white suspension was filtered through a Schlenk frit and the residue was washed 3 times with 10 mL of hexane. The remaining white powder was dried for 7 h at high vacuum giving 0.94 g (yield = 74 %) of pure product having the following analytical data: ¹ H NMR (200 MHz, C ₆ D ₆ , 25 ⁰ C): δ 1.31 (12 H, d, CH(CHs) ₂ ), 1.98 (6 η, s, CH ₃ ), 4.72 (2 η, sept, CHMe ₂ ); ¹³ C NMR (150.9 MHz, C ₆ D ₆ , 25 ⁰ C): δ 11.5 (2 C, s, CH ₃ ), 22.9 (4 C, s, NCH(CH ₃ ) ₂ ), 45.1 (2 C, s, NCHMe ₂ ), 112.8 (2 C, s, C=C), 147.8 (1 C, s, NCN); Found for CnH ₂₀ N ₃ Li: C 65.2 %, H 10.3 %, N 19.8 %; Calculated: C 65.6 %, H 10.0 %, N 20.9 %.

Then, a toluene solution Of (Im ² PrN)Li (98 mg, 0.487 mmol) was slowly added to the tungsten alkylidyne complex (Me ₃ CC≡W[OCMe(CF ₃ ) ₂ ] ₃ (dme)} (430 mg, 0.485 mmol), which was dissolved in a 100 mL Schlenk tube in 23 mL toluene and stirred for 10 min at room temperature. The yellow-orange suspension was filtered through an Schlenk frit to remove any by-products. Evaporation of the solvent and extraction with hexane afforded 487 mg of the product as yellow powder (63%). ¹ H NMR (400.1 MHz, C ₆ D ₆ , 25 ⁰ C): δ 1.14 (9 H, s, W≡CC(CH ₃ ) ₃ ), 1.16 (12 η, d, NCη(CH ₃ ) ₃ ), 1.46 (6 η, s, CCH ₃ ), 1.94 (6 η, br, C(CH ₃ )(CF ₃ ) ₂ ), 4.37 (2 η, sept, NCH(Cη ₃ ) ₃ ); ¹³ C NMR (150.9 MHz, C ₆ D ₆ , 25 ⁰ C): δ 9.1 (2 C, s, CCH ₃ ), 20.5 (4 C, s, NCH(CH ₃ ) ₂ ), 20.7 (2 C, s, OC(CH ₃ ) ₃ ), 33.8 (3 C, s, CC(CH ₃ ) ₃ ), 46.6 (2 C, s, NCHMe ₂ ), 50.1 (1 C, s, CCCH ₃ ), 81.0 (2 C, m, OCCF ₃ ), 117.4 (2 C, s, NC=CN), 124.1 ( ¹ JcF = 287 Hz, 2 C, q, CF ₃ ), 124.4 ( ¹ JcF = 287 Hz, 2 C, q, CF ₃ ), 158.6 (1 C, s, NCN), 284.0 ( ¹ JCw = 277 Hz, 1 C, s, W≡Q; ¹⁹ F NMR (376.5 MHz, C ₆ D ₆ , 25 ⁰ C): δ -78.6 ( ⁴ J _FF = 18 Hz, 6 F, q, CF ₃ ), -77.7 ( ⁴ J _FF = 18 Hz, 6 F, q, CF ₃ ); MS: 809 (M)

From the analytical results, the following structure of the catalyst was deduced:

Example 4: Synthesis of catalyst

A toluene solution Of (Im ² PrN)Li (149 mg, 0.741 mmol) was slowly added to the tungsten alkylidyne complex [Me3CC≡W(OCMe3)3] (350 mg, 0.741 mmol), which was dissolved in a 100 mL Schlenk tube in 15 mL toluene and stirred for 120 min at room temperature. The yellow-orange suspension was filtered through an Schlenk frit to remove any by-products. Evaporation of the solvent and extraction with hexane gave the pure product as a yellow powder in 46% isolated yield.

¹ H NMR (400.1 MHz, C ₆ D ₆ , 25 ⁰ C): δ 1.30 (12 H, d, NCH(CHs) ₂ ), 1.43 (9 H, s, W≡CC(CH ₃ ) ₃ ), 1.58 (6 η, s, CH ₃ ), (18 η, s, OC(CH ₃ ) ₃ ), 4.52 (2 η, sept, NCH); ¹³ C NMR (150.9 MHz, C ₆ D ₆ , 25 ⁰ C): δ 9.6 (2 C, s, CCH ₃ ), 21.4 (4 C, s, NCH(CH ₃ ) ₂ ), 33.5 (6C, s, OC(CH ₃ ) ₃ ), 34.9 (3 C, s, CC(CH ₃ ) ₃ ), 45.9 (2 C, s, NCHMe ₂ ), 50.1 (1 C, s, CCCH ₃ ), 76.7 (2 C, s, OCCH ₃ ), 115.8 (2 C, s, NC=CN), 159.8 (1 C, s, NCN), 270.7 ( ¹ JCw = 281 Hz, 1 C, s, W≡Q.

From the analytical results, the following structure of the catalyst was deduced:

Example 5: Alkyne metathesis of 1-phenylpropyne using the catalyst

As an example for alkyne transfer reactions using the catalyst of the invention, a solution of

220 mg (1.894-KT ³ mol) of 1-phenylpropyne

in 6 mL hexane and 1 mol% of catalyst obtained in Example 1 in hexane was stirred at room temperature under reduced pressure (350 mbar) to continuously remove 2-butyne. Filtration after 30 min through alumina and elution with hexane afforded the cross-metathesis product diphenylacetylene (to lane) in yields >90 %.

Analysis of the resultant product gave diphenylacetylene: ¹ H NMR (200 MHz, CDCI3, 25 ⁰ C): δ 7.34 (6 H, m, Ar), 7.53 (4 H, m, Ar); ¹³ C NMR (50.3 MHz, CDCl ₃ , 25 ⁰ C): δ 89.4 (2 C, s, C≡C), 123.3 (2C, s, Ar), 128.3 (2 C, s, Ar), 128.3 (4 C, Ar), 131.6 (4 C, s, Ar); Found for Ci ₄ Hi ₀ : C 93.5 %, H 5.9 %; Calculated C 94.3 %, H 5.7 %.

Example 6: Alkyne metathesis of l-(2-methylphenyl)propyne using the catalyst As an example for the high catalytic activity of the compounds of the invention in alkyne metathesis, the homodimerization of 1-phenylprop-l-yne was performed with a catalyst of the invention using standard equipment as the reaction could be performed at conditions at moderatedly elevated temperature and at moderately reduced pressure, namely in a rotary evaporator at 60 ⁰ C.

The stirred solution of 112 mg (0.861-10 ³ mol) of l-(2-methylphenyl)prop-l-yne in 10 mL hexane in the presence of 7.0 mg (0.864- 10 ^"5 mol) of catalyst obtained in Example 1 in hexane at 60 ⁰ C at reduced pressure (350 mbar) for 30 min, followed by filtration through alumina, elution with hexane, and evaporation of the solvent yielded 100% isolated bis-(2-methylphenyl)acetylene :

Analysis of the product gave bis-(2-methylphenyl)acetylene: ¹ H NMR (200.1 MHz, CDCl ₃ , 25

⁰ C): δ 2.53 (3 H, s, CH ₃ ), 2.53 (3 η, s, CH ₃ ), 7.23 (6 η, m, ArH), 7.50 (1 η, m, m-ArH), 7.53 (1 η, m, m-ArH); ¹³ C NMR (50.3 MHz, CDCl ₃ , 25 ⁰ C): δ 20.9 (2 C, s, CCH ₃ ), 92.3 (2 C, s, C≡C), 123.4 (2 C, s, CC≡C), 125.6 (2 C, s, Ar), 128.2 (2 C, s, Ar), 129.5 (2 C, s, Ar), 131.9 (2 C, s, Ar), 140.0 (2 C, s, Ar); Found for Ci ₆ Hi ₄ : C 92.5 %, H 7.4 %; Calculated C 93.2 %, H 6.8 %.

When performing the reaction at room temperature under otherwise identical conditions, 100% yield was found after 7 h.

Example 7: Ring-closing-metathesis using the catalyst

As an example for ring-closing-metathesis, a hexane solution of 6,15-dioxaeicosa-2,18-diyne (125.0 mg, 0.449 mmol) was added to a hexane solution of the catalyst obtained in Example 1 (7.3 mg, 4.49- 10 ⁵ mol, 2 mol%) and stirred for 2 h at room temperature under reduced pressure (350 mbar). Filtration through alumina and elution with hexane yielded the crude product after evaporation of the solvent. Pure product could be obtained by flash chromatography using hexane/ethylacetate 4:1 as the eluent in 95.1% yield as colorless syrup:

Analysis of the product gave: ¹ U NMR (400.1 MHz, C ₆ D ₆ , 25 ⁰ C): δ 1.45 (4 H, m, CH ₂ ), 1.54 (4 η, m, CH ₂ ), 1.65 (4 η, m, CH ₂ ), 2.27 (4 η, tt, C≡CCH ₂ ), 3.25 (4 η, t, OCH ₂ ), 3.31 (4 η, t, OCH ₂ ); ¹³ C NMR (50.3 MHz, C ₆ D ₆ , 25 ⁰ C): δ 20.9 (2 C, s, CH ₂ ), 24.8 (2 C, s, CH ₂ ), 27.7 (2 C, s, CH ₂ ), 29.3 (2 C, s, CH ₂ ), 69.1 (2 C, s, OCH ₂ ), 70.0 (2 C, s, OCH ₂ ), 79.0 (2 C, s, C≡C); Found for Ci ₆ Hi ₄ : C 72.9 %, H 10.7 %; Calculated C 74.9 %, H 10.8 %.

HR-MS (ESI): m/z 247.168 [M + Na]; GC-MS: m/z 223 (M) ^" , 209 (M -CH ₂ ⁺ ), 195 (M - C ₂ H ₄ ), 181 (M -C ₃ H ₇ ), 165 (M -C ₃ H ₇ O), 151 (M - C ₄ H ₉ O), 137 (M -C ₅ HnO), 123 (M - C ₆ Hi ₃ O), 109 (M -C ₇ Hi ₅ O), 96 (M -C ₈ Hi ₆ O), 81 (M -C ₈ Hi ₅ O ₂ ), 69 (M -C ₉ Hi ₅ O ₂ ), 55 (M - CnHi ₇ O ₂ ), 41 (M -Ci ₂ Hi ₉ O ₂ ).

Example 8: Ring-closing-metathesis using the catalyst

As a further example for the high catalytic activity of the compounds according to the invention, the following ring-closing reaction was performed:

A 3.1 mM hexane solution of the diyne (A) (150.0 mg, 0.055 mmol) and 2 mol% catalyst obtained in Example 1 (9.0 mg, 1.11-10 ⁵ mol) was stirred for 2 h at room temperature under reduced pressure (350 mbar). Filtration through alumina and elution with Et ₂ O afforded a mixture of monomeric (B) and dimeric (C) ring after evaporation of the solvent. Fractional crystallization from hexane yielded 19% of monomeric ring and 80% of dimeric ring, which is believed to be due to steric reasons.

For the monomeric ring (B) was found:

¹ H NMR (200.1 MHz, CDCl ₃ , 25 ⁰ C): δ 2.41 (4 H, tt, C≡CCH ₂ ), 3.73 (4 η, t, OCH ₂ ), 4.87 (4 η, s, OCH ₂ ), 7.33 (4 η, m, ArH); ¹³ C NMR (50.3 MHz, CDCl ₃ , 25 ⁰ C): δ 21.2 (2 C, s, C≡CCH ₂ ), 68.4 (2 C, s, OCH ₂ ), 71.7 (2 C, s, OCH ₂ ), 80.9 (2 C, s, C≡C), 128.1 (2 C, s, Ar), 130.1 (4 C, s, Ar), 138.5 (4 C, s, Ar); MS (ESI): m/z 239.1 [M + Na].

For the dimeric ring (C) was found:

¹ H NMR (200.1 MHz, CDCl ₃ , 25 ⁰ C): δ 2.50 (8 H, tt, C≡CCH ₂ ), 3.62 (8 η, t, OCH ₂ ), 4.68 (8 η, s, OCH ₂ ), 7.33 (8 η, m, ArH); ¹³ C NMR (50.3 MHz, CDCl ₃ , 25 ⁰ C): δ 19.6 (4 C, s, C≡CCH ₂ ), 68.5 (4 C, s, OCH ₂ ), 70.3 (4 C, s, OCH ₂ ), 77.7 (4 C, s, C≡C), 127.3 (4 C, s, Ar),

128.5 (4 C, s, Ar), 135.9 (4 C, s, Ar); Found for C ₂₈ H ₃₂ O ₄ : C 77.1%, H 7.3%; Calculated C 77.7%, H 7.5%; MS (ESI): m/z 455.2 [M + Na].

Example 9: Synthesis of catalyst

As an example for a catalyst of the third embodiment, the structure identified below was synthesized. A toluene solution OfLi(NtBuAr)(OEt ₂ ) obtainable e.g. according to Laplaza et al, Organometallics 577-580 (1995), (51 mg, 0.200 mmol) was added to the tungsten alkylidyne complex (Me3CC≡W[OCMe(CF3)2(dme)} (153 mg, 0.198 mmol), which was dissolved in 12 mL toluene and stirred for 30 min at room temperature. Evaporation of the solvent and any volatile by-products gave a light yellow residue. The powder was re- dissolved in 8 mL hexane and cooled to -35 ⁰ C for 6 h. Filtration and evaporation of the solvent gave the product as light yellow powder, which can be recrystallized from a cold hexane solution.

¹ H NMR (400.1 MHz, C ₆ D ₆ , 25 ⁰ C): δ 0.66 (9 H, s, C(CHs) ₃ ), 1.16 (9 H, s, C(CHs) ₃ ), 1.73 (6 η, m, C(CH ₃ )(CFs) ₂ ), 2.13 (6 η, s, ArCH ₃ ), 6.62 (1 η, m, ArH), 6.70 (2 η, s, ArH); ¹³ C NMR (150.9 MHz, C ₆ D ₆ , 25 ⁰ C): δ 20.2 (s, OCCH ₃ ), 21.3 (s, ArCH ₃ ), 28.7 (s, CC(CH ₃ ) ₃ ), 31.4 (s, C(CH ₃ )S), 51.5 ( ² Jcw = 39 Hz, CCCH ₃ ), 60.5 (s, NCMe ₃ ), 81.9 (m, OCCF3), 123.9 ( ¹ JcF = 287 Hz, q, CF3), 124.2 ( ¹ J ₀ F = 287 Hz, q, CF3), 126.2 (s, C aryl) 127.4 (s, C aryl meta), 128.3 (s, C aryl), 137.0 (s, C aryl meta), 159.2 (s, C aryl ipso), 298.2 ( ¹ J ₀ W = 286 Hz, s, W≡C); ¹⁹ F NMR (376.5 MHz, C ₆ D ₆ , 25 ⁰ C): δ -78.8 ( ⁴ J _FF = 18 Hz, 6 F, q, CF ₃ ), -77.9 ( ⁴ J _FF = 18 Hz, 6 F, q, CF ₃ ); CHN: calcd. for C ₂₅ H ₃₃ NFi ₂ O ₂ W: C 37.94 %, H 4.20 %, N 1.77 %; found: C 36.97 %, H 4.66 %, N 2.11 %.

From the data, the following structure of the catalyst was deduced:

This catalyst could be used in the synthesis reaction according to Examples 5 to 8 with similar results.

Example 10: Synthesis of catalyst

As an example for a catylyst of the second embodiment, the structure identified below was synthesized. A toluene solution of Li(NPCy3) (68 mg, 0.230 mmol) (Cy = C6H11) was added to the tungsten alkylidyne complex (Me3CC≡W[OCMe(CF3)2(dme)} (200.6 mg, 0.230 mmol), which was dissolved in 10 mL toluene and stirred for 12 h at room temperature. Evaporation of the solvent and any volatile by-products gave a yellow residue. Washing the crude product several times with a minimum amount of hexane and subsequent evaporation of the solvent gave the product as yellow powder in 80 % yield.

¹ H NMR (300.1 MHz, C ₆ D ₆ , 25 ⁰ C): δ 1.27 (9 H, s, C(CHs) ₃ ), 1.03-1.87 (33 H, m, C ₆ Hn), 1.92 (6 η, m, C(CH ₃ )(CFs) ₂ ); ¹³ C NMR (75.5 MHz, C ₆ D ₆ , 25 ⁰ C): δ 20.4 (s, OCCH3), 25.8 ( ⁴ Jcp = 1 Hz, d, Cy), 26.2 ( ³ JCP = 3 Hz, d, Cy), 26.6 ( ² J _C p = 12 Hz, d, Cy), 34.0 ( ⁵ J _C p = 1 Hz, d, CMe3), 35.3 ( ¹ JcP = 57 Hz, d, Cy ipso-Q, 49.4 ( ⁴ J _CP = 1 Hz, CCMe ₃ ), 80.8 (m, OCCF ₃ ), 124.4 ( ¹ JcF = 287 Hz, q, CF3), 124.0 ( ¹ JcF = 287 Hz, q, CF ₃ ), 285.8 ( ³ J _C p = 7 Hz, d, W≡C); ¹⁹ F NMR (188.3 MHz, C ₆ D ₆ , 25 ⁰ C): δ -78.4 ( ⁴ J _FF = 18 Hz, 6 F, q, CF ₃ ), -77.6 ( ⁴ J _FF = 18 Hz, 6 F, q, CF3); ³¹ P NMR (121.5 MHz, C ₆ D ₆ , 25 ⁰ C): δ 44.9 ( ² J _PW = 110 Hz, t, PCy3).

From the data, the following structure of the catalyst was deduced:

This catalyst could be used in the synthesis reaction according to Examples 5 to 8 with similar results.