New borane-amine complexes and their application in Suzuki-type cross-coupling reactions

Field of the Invention

The invention relates to new amine complexes of B-organyl-9-borabicyclo[3.3.1]no- nanes and to solutions of said complexes. Furthermore, the invention relates to a method of using trialkylborane-amine complexes in Suzuki-type cross-coupling reactions and to a process to form new carbon-carbon bonds in a Suzuki-type cross- coupling reaction with a triorganoborane, which is carried out in the presence of an amine.

Background of the Invention

The transition metal-catalyzed cross-coupling reaction between organic electrophiles and organoboron derivatives to form new carbon-carbon bonds is known as Suzuki- type cross-coupling reaction (Miyaura, N.; Suzuki, A., Chem. Rev. 95, pages 2457 to 2483 (1995)). For example, triorganoboranes can be used as sources for a nucleophilic organic moiety that will be coupled to an organic electrophile in this Suzuki-type cross- coupling reactions. Readily available B-organyl-9-borabicyclo[3.3.1]nonanes (B- organyl-9-BBN ^' s) are especially useful reagents in said cross-coupling reactions since the exocyclic alkyl group is coupled preferentially over the bicyclic 9-borabicyc- lo[3.3.1]nonane skeleton (Miyaura, N.; Suzuki, A. et al., J. Am. Chem. Soc. 1 11 , pages 314 to 321 (1989); Netherton, M. R. et al., J. Am. Chem. Soc. 123, pages 10099 to 10100 (2001 )).

Hydroboration of alkenes or alkynes with 9-borabicyclo[3.3.1]nonane (9-BBN) provides easy access to many B-organyl-9-borabicyclo[3.3.1]nonanes. In favourable cases formation of the B-organyl-9-BBN via hydroboration of an appropriate alkene and the sub- sequent Suzuki-type cross-coupling reaction with an organic electrophile can be conducted as one-pot synthesis with the two steps run consecutively in the same reaction vessel (e. g. Rodriguez, A. et al., Org. Biomol. Chem. 1 , pages 973 to 977 (2003)).

Owing to its dimeric structure 9-BBN forms a pyrophoric solid with only poor solubility in typical organic solvents (Soderquist, J. A.; Brown, H. C, J. Org. Chem. 46, pages 4599 to 4600 (1981)). These properties may hamper the large scale application of 9-BBN and so alternatives are desirable.

It is known that the 9-BBN dimer can be split by addition of certain Lewis bases and that in some cases stable 9-BBN-Lewis base complexes are formed (Brown, H. C. et al., J. Am. Chem. Soc. 104, pages 7148 to 7155 (1982); Gazzetta Chimica Italians 117, pages 517 to 523 (1987)). However, the 9-BBN-pyridine complex (Brown, H. C, J. Org. Chem. 45, pages 846 to 849 (1980)) shows only a relatively poor ability to act as a hy-

droborating agent (Brown, H. C. et al., Inorg. Chem. 16, pages 3090 to 3094 (1977)). Recently, new dialkylborane-amine complexes have been developed that are more suitable for hydroboration reactions and therefore give access to the corresponding trialkylborane-amine complexes or mixtures (WO 2008/055859).

It was an object of the present invention to develop new trialkylborane-amine complexes and solutions thereof. It was another object of the present invention to provide a new method of using trialkylborane-amine complexes in Suzuki-type cross-coupling reactions. It was still another object of the present invention to develop a process to form new carbon-carbon bonds in a Suzuki-type cross-coupling reaction, which is carried out in the presence of an amine.

Summary of the Invention

Accordingly, new B-organyl-9-borabicyclo[3.3.1]nonane-amine complexes of the formula (1) have been found,

wherein

R ¹ is an organyl comprising at least one carbon atom that is directly bound to the boron atom, and amine is a substituted pyridine of the formula (2)

wherein

R ² is Ci - Cio alkyl, Ci - Cs alkoxy or Ci - Cs-alkoxy-Ci - Cio alkyl, and R ³ is hydrogen or a Ci - Cio alkyl, Ci - Cs alkoxy or Ci - Cs-alkoxy-Ci - Cio alkyl group, or an alkylamine of the formula (3)

R ⁴ R ⁵ NH (3),

wherein

R ⁴ is hydrogen or Ci - C10 alkyl, and R ⁵ is Ci - Cio alkyl.

Another embodiment of the present invention are solutions comprising at least one of the new B-organyl-9-borabicyclo[3.3.1]nonane-amine complexes of the formula (1 ) and at least one solvent.

Still another embodiment of the present invention is a new method of using B-organyl- 9-BBN-amine complexes of the formula (1) in Suzuki-type cross-coupling reactions to form new carbon-carbon bonds.

Furthermore, a process has been found to form new carbon-carbon bonds comprising a Suzuki-type cross-coupling reaction with a triorganoborane, which is carried out in the presence of an amine.

Detailed Description of the Invention

The new B-organyl-9-borabicyclo[3.3.1]nonane-amine complexes of the present invention have chemical structures according to the general formula (1 ),

wherein

R ¹ is an organyl comprising at least one carbon atom that is directly bound to the boron atom, and amine is a substituted pyridine of the formula (2)

wherein

R ² is Ci - Cio alkyl, Ci - Cs alkoxy or Ci - Cs-alkoxy-Ci - Cio alkyl, and

R ³ is hydrogen or a Ci - Cio alkyl, Ci - Cs alkoxy or Ci - Cs-alkoxy-Ci - Cio alkyl group, or an alkylamine of the formula (3)

R ⁴ R ⁵ NH (3), wherein

R ⁴ is hydrogen or Ci - Cio alkyl, and R ⁵ is Ci - Cio alkyl.

In a preferred embodiment of the present invention the new B-organyl-9-BBN-amine complexes have chemical structures according to the general formula (1), wherein the amine is a substituted pyridine of the formula (2).

As used in connection with the present invention, the term "organyl" denotes an organic group comprising at least one carbon atom, that may contain heteroatoms like hydrogen, oxygen, nitrogen, sulphur, phosphorus, fluorine, chlorine, bromine, iodine, boron, silicon, selenium, tin or transition metals like iron, nickel, zinc, platinum, etc. The organyl can have any linear or cyclic, branched or unbranched, mono- or polycyclic, carbo- or heterocyclic, saturated or unsaturated molecular structure and may comprise protected or unprotected functional groups. Furthermore, the organyl may be linked to or part of an oligomer or polymer with a molecular weight up to one million Dalton.

Preferred organyl groups are Ci - C24 alkyl, C3 - C16 cycloalkyl, substituted alkyl, C2 - C22 alkenyl, C5 - C15 cycloalkenyl and C2 - C22 alkynyl groups.

As used in connection with the present invention, the term "Ci - C24 alkyl" denotes a branched or an unbranched saturated hydrocarbon group comprising between 1 and 24 carbon atoms; examples are methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec- butyl, tert-butyl, amyl, isoamyl, sec-amyl, 1 ,2-dimethylpropyl, 1 ,1-dimethylpropyl, hexyl, 4-methylpentyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 1 ,1-dimethylbutyl, 2,2- dimethylbutyl, 3,3-dimethylbutyl, 1 ,2-dimethylbutyl, 1 ,3-dimethylbutyl, 1 ,2,2-trimethyl- propyl, 1 ,1 ,2-trimethylpropyl, heptyl, 5-methylhexyl, 1-methylhexyl, 2,2-dimethylpentyl, 3,3-dimethylpentyl, 4,4-dimethylpentyl, 1 ,2-dimethylpentyl, 1 ,3-dimethylpentyl, 1 ,4- dimethylpentyl, 1 ,2,3-trimethylbutyl, 1 ,1 ,2-trimethylbutyl, 1 ,1 ,3-trimethylbutyl, octyl, 6- methylheptyl, 1-methylheptyl, 1 ,1 ,3,3-tetramethylbutyl, nonyl, 1-, 2-, 3-, 4-, 5-, 6- or 7- methyloctyl, 1-, 2-, 3-, 4- or 5-ethylheptyl, 1-, 2- or 3-propylhexyl, decyl, 1-, 2-, 3-, 4-, 5-, 6-, 7- and 8-methylnonyl, 1-, 2-, 3-, 4-, 5- or 6-ethyloctyl, 1-, 2-, 3- or 4-propylheptyl, undecyl, 1-, 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-methyldecyl, 1-, 2-, 3-, 4-, 5-, 6- or 7-ethylnonyl, 1-, 2-, 3-, 4- or 5-propyloctyl, 1-, 2- or 3-butylheptyl, 1-pentylhexyl, dodecyl, 1-, 2-, 3-, 4- , 5-, 6-, 7-, 8-, 9- or 10-methylundecyl, 1-, 2-, 3-, 4-, 5-, 6-, 7- or δ-ethyldecyl, 1-, 2-, 3-, 4-, 5- or 6-propylnonyl, 1-, 2-, 3- or 4-butyloctyl, 1-2-pentylheptyl and isopinocampheyl. Preferred are the alkyl groups ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert- butyl, amyl, isoamyl, sec-amyl, 1 ,2-dimethylpropyl, 1 ,1-dimethylpropyl, hexyl and octyl.

The term "C3 - C16 cycloalkyl" denotes a saturated hydrocarbon group comprising between 3 and 16 carbon atoms including a mono- or polycyclic structural moiety. Exam-

pies are cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyc- lononyl or cyclodecyl. Prefered are the cycloalkyl groups cyclopropyl, cyclopentyl and cyclohexyl.

The term "substituted alkyl" denotes an alkyl group in which at least one hydrogen atom is replaced by a halide atom like fluorine, chlorine, bromine or iodine, a Ci - C20 alkoxy group, an ester group, a trialkylsilyl group, a Cβ - C14 aryl group, or a C3 - C14 heteroaryl group.

The term "Ci - C20 alkoxy" stands for a group derived from an aliphatic monoalcohol with between 1 and 20 carbon atoms.

The term "Cβ - C14 aryl" denotes an unsaturated hydrocarbon group comprising between 6 and 14 carbon atoms including at least one aromatic ring system like phenyl or naphthyl or any other aromatic ring system.

The term "C3 - C14 heteroaryl" denotes a mono- or polycyclic aromatic ring system comprising between 3 and 14 ring atoms, in which at least one of the ring carbon atoms is replaced by a heteroatom like nitrogen, oxygen or sulfur. Examples are pyridyl, pyranyl, thiopyranyl, chinolinyl, isochinolinyl, acridyl, pyridazinyl, pyrimidyl, pyrazinyl, phenazinyl, triazinyl, pyrrolyl, furanyl, thiophenyl, indolyl, isoindolyl, pyrazolyl, imida- zolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl and triazolyl.

The term "C2 - C22 alkenyl" denotes a straight chain or branched unsaturated hydrocar- bon group comprising between 2 and 22 carbon atoms including at least one carbon- carbon double bond. Examples are vinyl, allyl, 1-methylvinyl, butenyl, isobutenyl, 3- methyl-2-butenyl, 1-pentenyl, 1-hexenyl, 3-hexenyl, 2,5-dimethylhex-4-en-3-yl, 1- heptenyl, 3-heptenyl, 1-octenyl, 1-nonenyl, 2-nonenyl, 3-nonenyl, 1-decenyl, 3-decenyl, 1 ,3-butadienyl, 1-4-pentadienyl, 1 ,3-hexadienyl and 1 ,4-hexadienyl. Prefered are the alkenyl groups vinyl, allyl, butenyl, isobutenyl, 1 ,3-butadienyl and 2,5-dimethylhex-4-en- 3-yl.

The term "C5 - C15 cycloalkenyl" denotes an unsaturated hydrocarbon group comprising between 5 and 15 carbon atoms including at least one carbon-carbon double bond and a mono- or polycyclic structural moiety. Examples are cyclopentenyl, 1-methylcyclo- pentenyl, cyclohexenyl, cyclooctenyl, 1 ,3-cyclopentadienyl, 1 ,3-cyclohexadienyl, 1 ,4- cyclohexadienyl, 1 ,3-cycloheptadienyl, 1 ,3,5-cycloheptatrienyl and 1 ,3,5,7-cycloocta- tetraenyl.

The term "C2 - C22 alkynyl" denotes a straight chain or branched unsaturated hydrocarbon group comprising between 2 and 22 carbon atoms including at least one carbon-

carbon triple bond. Examples of alkynyl groups include ethynyl, 2-propynyl and 2- or 3- butynyl.

According to the invention, the substituted pyridine of the formula (2) can be, for exam- pie, 2-picoline, 2,3-lutidine, 2,4-lutidine, 2,5-lutidine, 5-ethyl-2-methylpyridine, 4-ethyl-2- methylpyridine, 3-ethyl-2-methylpyridine, 2,5-diethylpyridine, 5-propyl-2-methylpyridine, 4-propyl-2-methylpyridine, 5-isopropyl-2-methylpyridine, 5-t-butyl-2-methylpyridine, 5-n- hexyl-2-methylpyridine, 4-isobutyl-2-methylpyridine or 2,4-dipropylpyridine. Preferred pyridines of the formula (2) are 2-picoline, 2,3-lutidine, 2,4-lutidine, 2,5-lutidine and 5- ethyl-2-methylpyridine.

In a preferred embodiment of the present invention the new B-organyl-9-BBN-amine complexes have chemical structures according to the general formula (1 ), wherein R ¹ is an organyl that is directly bound to the boron atom via two methylene groups and (1 ) exhibits a moiety of the formula >BCH ₂ CH ₂ - , i. e. R ¹ is -CH ₂ CH ₃ or -CH ₂ CH ₂ -organyl. These preferred derivatives of (1 ) can, for example, be synthesized via hydroboration of terminal alkenes with 9-BBN or 9-BBN-amine complexes, owing to the well-known anti-Markovnikov regioselectivty of such hydroborations. Examples for these preferred B-organyl-9-BBN-amine complexes (1) have chemical structures according to the gen- eral formula (1 ), wherein R ¹ is ethyl, propyl, butyl, pentyl, hexyl and octyl.

In cases where the organyl R ¹ is substituted at the -BCH ₂ CH ₂ - moiety the R ¹ group becomes more bulky and complexation between the amine and the triorganoborane might be hampered. In some cases a mixture of the new B-organyl-9-BBN-amine com- plex and the uncomplexed B-organyl-9-BBN is observed, in other cases there is no complexation at all. However, compositions comprising any amine and a B-organyl-9- BBN derivative can very often be used for further reactions independent from complex formation (see below).

In another preferred embodiment of the present invention the new B-organyl-9-BBN- amine complexes have chemical structures according to the general formula (1 ), wherein the amine is a compound according to the formula (2), wherein R ³ is hydrogen or Ci - C4-alkyl.

Most preferred is an embodiment of the present invention where the new B-organyl-9- BBN-amine complexes have chemical structures according to the general formula (1), wherein R ¹ is -CH ₂ CHs or -CH ₂ CH ₂ -organyl and the amine is 2-picoline, 2,3-lutidine, 2,4-lutidine, 2,5-lutidine or 5-ethyl-2-methylpyridine.

The ¹¹ B NMR spectra of the new B-organyl-9-BBN-amine complexes of the formula (1 ) generally show a broad singlet with a chemical shift δ between +10 to +35 ppm, indicating strong coordination between the amine and the trialkylborane moieties in solution.

For example, the B-octyl-9-borabicyclo[3.3.1]nonane-2-picoline complex shows a ¹¹ B NMR resonance at δ = 26.6 ppm (cf. example 1 ).

The new B-organyl-9-BBN-amine complexes (1 ) can, for example, be obtained via hy- droboration of an unsaturated compound like an alkene or an alkyne with 9-BBN or a 9- BBN-Lewis base complex (e. g. 9-BBN-THF or 9-BBN-dimethyl sulfide) followed by adding the respective amine of the formula (2) or (3) to the resulting B-organyl-9-BBN derivative. Alternatively, the hydroboration of an alkene or alkyne can be conducted directly with a complex of 9-BBN and an amine of the formula (2) or (3).

Another embodiment of the present invention is therefore a process to synthesize new B-organyl-9-BBN-amine complexes of the formula (1 ), comprising the step of hydrobo- rating an alkene or an alkyne with a complex of 9-BBN and an amine of the formula (2) or (3) or hydroborating an alkene or an alkyne with 9-BBN or a 9-BBN-Lewis base complex followed by adding an amine of the formula (2) or (3).

If necessary, the hydroboration of alkenes or alkynes with 9-BBN or a complex of 9- BBN can be carried out in solution in the presence of at least one solvent. Preferably, complexes of 9-BBN and an amine of the formula (2) or (3) are reacted with alkenes or alkynes in organic solvents. Owing to the generally higher solubility of these 9-BBN- amine complexes in organic solvents compared to 9-BBN this allows for working at higher concentrations, thereby permitting higher loadings of reactors and avoids the difficulties connected with the handling of 9-BBN as a pyrophoric solid. The initial products of this synthetic route are therefore solutions of the new B-organyl-9-BBN-amine complexes (1). These solutions can either be directly employed for further reactions or the new B-organyl-9-BBN-amine complexes (1) can be isolated in pure form by evaporation of the solvent. The preferred method for removal of the solvent is evaporation under reduced pressure to decrease the boiling point of the solvent.

Another embodiment of the present invention is therefore a solution comprising at least one B-organyl-9-BBN-amine complexes of the formula (1 ) and at least one solvent. Suitable solvents for the solutions of the present invention are those in which the B- organyl-9-BBN-amine complexes have a high solubility. Examples are ethers like diethyl ether, tetrahydrofuran or 2-methyltetrahydrofuran, sulfides like dimethyl sulfide or 1 ,6-thioxane and hydrocarbons like pentane, hexane(s), heptane(s), cyclohexane, toluene or xylenes. Preferred solvents for the solutions comprising at least one B-organyl- 9-BBN-amine complex of the formula (1) are tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfide, 1 ,6-thioxane, toluene, hexane(s), heptane(s) or cyclohexane, most preferred are tetrahydrofuran, 2-methyltetrahydrofuran, toluene, hexane(s), heptane(s) or cyclohexane.

The solutions of the present invention generally contain the new B-organyl-9-BBN- amine complexes of the formula (1) in concentrations between 0.05 and 5 mol/l, preferably between 0.1 and 5 mol/l, more preferably between 0.5 and 3 mol/l.

Another embodiment of the present invention is a process to synthesize a solution comprising at least one of the new B-organyl-9-BBN-amine complexes of the formula (1 ) and at least one solvent, comprising the steps of hydroborating an alkene or an alkyne with a complex of 9-BBN and an amine of the formula (2) or (3) or hydroborating an alkene or an alkyne with 9-BBN or a 9-BBN-Lewis base complex followed by adding an amine of the formula (2) or (3) in at least one solvent.

Still another embodiment of the present invention is a process to synthesize the new B- organyl-9-BBN-amine complexes of the formula (1), comprising the steps of hydroborating an alkene or an alkyne with a complex of 9-BBN and an amine of the formula (2) or (3) or hydroborating an alkene or an alkyne with 9-BBN or a 9-BBN-Lewis base complex followed by adding an amine of the formula (2) or (3) in at least one solvent and isolating the complex from the formed solution. Preferably the isolation is done by evaporation of the solvent.

The present invention further provides a new method of using the new B-organyl-9- BBN-amine complexes of the formula (1) in Suzuki-type cross-coupling reactions to form new carbon-carbon bonds. The direct use of the new B-organyl-9-BBN-amine complexes of the formula (1) in Suzuki-type cross-coupling reactions without the need to separate the trialkylborane from the amine is highly desirable for development of cost effective processes.

Moreover, it was found that in Suzuki-type cross coupling reactions with trialkylboranes as nucleophile the presence of an amine does not interfere with the catalytic cycle. It turned out to be irrelevant whether there is a complex formed between the trialkylbo- rane and the amine or not or if there is a dynamic equilibrium between the complex and the separated trialkylborane and amine species. This is of great value since trialkylboranes are easily prepared via hydroboration of alkenes and alkynes with dialkylborane- amine complexes, which are much easier to handle and have a much higher solubility than the corresponding dialkylboranes without any amine. Therefore, the crude product of the reaction between a dialkylborane-amine complex and an alkene or alkyne can be used directly in a Suzuki-type cross-coupling reaction.

Therefore, a further aspect of the present invention is a process to form new carbon- carbon bonds comprising a Suzuki-type cross-coupling reaction with a triorganoborane, which is carried out in the presence of an amine.

Another embodiment of the present invention is a process to form new carbon-carbon bonds comprising the steps of hydroborating an alkene or alkyne with a diorganobo- rane-amine complex and using the resulting mixture of a triorganoborane and the amine in a Suzuki-type cross-coupling reaction.

In one embodiment of the present invention the triorganoborane in these processes is a B-organyl-9-BBN derivative, e. g. B-octyl-9-BBN. In another embodiment of present invention the amine in these processes is a substituted pyridine of the formula (2) or an alkylamine of the formula (3) as defined above.

Examples

The following examples illustrate the present invention without limitation of the same. All reactions were performed under dry and oxygen free conditions.

Example 1 :

Hydroboration of 1-octene with 9-BBN-2-picoline complex

29.5 g of a 43.1 wt% solution of 9-BBN-2-picoline complex in THF (60 mmol) were di- luted with 6.5 ml of anhydrous THF and cooled to 0 ⁰ C. 6.73 g of 1-octene (60 mmol) were added slowly and the mixture was stirred at room temperature for three hours. After that analysis of the reaction mixture by ¹¹ B NMR spectroscopy revealed that no 9-BBN-2-picoline complex (δ = -1.6 ppm) was left and a major peak at 26.6 ppm was visible assigned to B-octyl-9-BBN-2-picoline complex. This prepared 1.02 M stock solu- tion of B-octyl-9-BBN-2-picoline complex in THF was used for the following Suzuki experiments.

Example 2:

Hydroboration of methyl-10-undecenoate with 9-BBN-2-picoline complex

2.5 g of a 43.1 wt% solution of 9-BBN-2-picoline complex in THF (5 mmol) were diluted with 10 ml of anhydrous THF. Then 1.12 ml of methyl-10-undecenoate (5 mmol) were added dropwise and the mixture was stirred at room temperature for three hours. After that analysis of the reaction mixture by ¹¹ B NMR spectroscopy revealed that no 9-BBN- 2-picoline complex (δ = -1.6 ppm) was left and a major peak at δ = 29.6 ppm was visible, assigned to B-(1 1-methylundecanoate)-9-BBN-2-picoline complex.

Example 3:

Hydroboration of isoprene with 9-BBN-2-picoline complex

2.69 g of a 40 wt% solution of 9-BBN-2-picoline complex in THF (5 mmol) were diluted with 10 ml of anhydrous THF. Then 0.5 ml of isoprene (5 mmol) were added and the

mixture was stirred at room temperature for 24 hours. After that analysis of the reaction mixture by ¹¹ B NMR spectroscopy revealed that no 9-BBN-2-picoline complex (δ = -1.6 ppm) was left. Two resonances were abserved at δ = 76.1 ppm and 18.1 ppm assigned to the complexed and uncomplexed product (1 : 0.71 = triorganylborane-2-picoline : triorganylborane). The proton spectra showed the formation of two isomers caused by addition to either of the double bonds of isoprene

Example 4:

Suzuki coupling of iodobenzene and B-octyl-9-BBN-2-picoline complex (sp ² -sp ³ )

123 mg (0.15 mmol) of PdCI ₂ (dppf).DCM complex ([1 ,1 ^' -bis(diphenylphosphino)- ferrocene]dichloropalladium-(ll)-complex with dichloromethane), 12 ml distilled THF and 1.02 g (5 mmol) iodobenzene were mixed. Then, 7.53 g of a 16 wt% solution of B-octyl-9-BBN-2-picoline complex in THF were added followed by 5 ml of a 3 M aqueous sodium hydroxide (NaOH) solution, which resulted in a dark brown reaction mix- ture. The mixture was heated to reflux for 22 hours. Then it was cooled to room temperature, hexane (20 ml) was added and the mixture was quenched with hydrogen peroxide hydrogen peroxide (H2O2, 30w%, 2 ml). Stirring was continued for 10 minutes until the gas evolution ceased. The aqueous layer was separated from the organic layer, extracted with hexane (1 x 20 ml) and the combined organic layers were dried over sodium sulfate (Na2SU4), filtered and evaporated to dryness. The crude product (1.83 g) was purified by column chromatography on silica gel (pure hexane) to give 558 mg (59%) of pure 1-octylbenzene as a colorless oil.

Example 5: Suzuki Coupling of 1-iodo-4-nitrobenzene and B-octyl-9-BBN-2-picoline complex (sp ² - sp ³ )

204 mg (0.25 mmol) of PdCI ₂ (dppf).DCM complex, 14.6 ml distilled THF and 1.245 g (5 mmol) 1-iodo-4-nitrobenzene were mixed. Then 5.39 ml of a 1.02 M solution of B- octyl-9-BBN-2-picoline complex was added followed by 3.33 ml of a 3 M aqueous potassium phosphate (K3PO4) solution, which resulted in a black reaction mixture. The mixture was stirred for 21 h, then hexane (20 ml), followed by water (5 ml) and hydrogen peroxide (H2O2, 30w%, 2 ml) were added. Stirring was continued for 10 minutes until the gas evolution ceased. The black mixture was filtered over a pad of celite, the aqueous layer was separated from the organic layer and extracted with diethyl ether (2 x 15 ml). The combined organic layers were dried over sodium sulfate (Na2SU4), filtered and evaporated to dryness. The crude product was purified by column chromatography on silica gel (pure hexane) to result in 0.70 g (60 %) of 1-nitro-4-octylbenzene as a colorless oil.

Example 6:

Suzuki Coupling of methyl-4-bromobenzoate and B-octyl-9-BBN-2-picoline complex (sp ² -sp ³ )

204 mg (0.25 mmol) of PdCI ₂ (dppf).DCM complex, 14.6 ml distilled THF and 1.08 g (5 mmol) methyl-4-bromobenzoate were mixed. Then 5.39 ml of a 1.02 M solution of B- octyl-9-BBN-2-picoline complex was added followed by 3.33 ml of a 3 M aqueous potassium phosphate (K3PO4) solution, which resulted in a black reaction mixture. The mixture was stirred for 23 h, then hexane (20 ml), followed by water (5 ml) and hydrogen peroxide (H2O2, 30w%, 2 ml) were added. Stirring was continued for 10 minutes until the gas evolution ceased. The aqueous layer was separated from the organic layer and extracted with diethyl ether (2 x 15 ml). The combined organic layers were dried over sodium sulfate (Na ₂ SO ₄ ), filtered and evaporated to dryness. The crude product was purified by column chromatography on silica gel (gradient elution: pure hexane to hexane : ethyl acetate = 97 : 3) to result in 1.24 g (99 %) of methyl-4- octylbenzoate as a colorless oil.

Example 7:

Suzuki coupling of ethyl-4-bromobutanoate and B-octyl-9-BBN-2-picoline complex (sp ³ - sp ³ )

1.38 g (6 mmol) of solid potassium phosphate (K3PO4.H2O), 50 mg (0.2 mmol) of PaI- ladium-(ll)-acetate (Pd(OAc)2) and 1 12 mg (0.4 mmol) of tricyclohexylphophine (P(Cy)3) were mixed. The mixture was purged with nitrogen for 15 minutes and then 5.88 ml of a 1.02 M solution of B-octyl-9-BBN-2-picoline complex (6 mmol) in THF was added to the solids. The mixture was diluted with 5.9 ml anhydrous THF and treated with ethyl-4-brombutanoate (975 mg, 5.0 mmol). The black suspension was stirred for 22 h at room temperature, than hydrogen peroxide (H2O2, 30w%, 2 ml) was added and stirring was continued for another 10 minutes. After that, diethyl ether (20 ml), followed by water (5 ml) was added. The aqueous layer was separated from the organic layer and extracted twice with diethyl ether (2 x 15 ml). The combined organic layers were dried over sodium sulfate (Na2SU4), filtered and evaporated to dryness. The crude product was purified by column chromatography on silica gel (pure hexane) to result in 870 mg (73 %) of ethyl dodecanoate as a colorless oil.

All the references described above are incorporated by reference in its entirety for all useful purposes.

While there are shown and described certain specific structures embodying the invention, it will be manifest to those skilled in the art that various modifications and rearrangements of the parts may be made without departing from the spirit and scope of the underlying inventive concept and the same is not limited to the particular forms herein shown and described.