Gold-Catalyzed C-C Cross-Coupling of Boron- and Silicon-Containing Aryl Compounds and Aryldiazonium Compounds by Visible-Light

Abstract

The present invention relates to a method for producing (functionalized) biaryls by employing a visible-light-driven, gold-catalyzed CC cross-coupling reaction system involving boron- and silicon-containing aryl compounds and aryldiazonium compounds. Moreover, the present invention relates to the use of such boron- and silicon-containing aryl compounds and aryldiazonium compounds, as well as related gold catalysts, in the manufacture of (functionalized) biaryls.

Claims

1. A method for manufacturing biaryl compounds, comprising the steps: (a) providing a mixture containing a boron-containing aryl compound represented by the following Formula (i) or a silicon-containing aryl compound represented by the following Formula (ii), an aryldiazonium compound represented by the following Formula (iii) and a gold(I) catalyst in a solvent ##STR00065## wherein Ar.sup.1 and Ar.sup.2 are each independently selected from a C.sub.3-C.sub.12 aryl group and a C.sub.3-C.sub.12 heteroaryl group, and each group Ar.sup.1 and Ar.sup.2 may independently contain one or more substituent(s), in Formula (i) R.sup.1, R.sup.2 and R.sup.3 are each independently selected from hydroxy, amino, halogen, C.sub.1-C.sub.12 alkyl, C.sub.1-C.sub.12 alkoxy, C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12 alkenyloxy, C.sub.2-C.sub.12 alkynyl, C.sub.2-C.sub.12 alkynyloxy, C.sub.3-C.sub.12 aryl and C.sub.3-C.sub.12 aryloxy, n represents an integer of 0 or 1, wherein two or more of R.sup.1, R.sup.2 and R.sup.3 may be bound to each other to form one or more rings and M represents a cation selected from Li, Na, K and ammonium, in Formula (ii) R.sup.4, R.sup.5, R.sup.6 and R.sup.7 are each independently selected from hydroxy, amino, halogen, C.sub.1-C.sub.12 alkyl, C.sub.1-C.sub.12 alkoxy, C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12 alkenyloxy, C.sub.2-C.sub.12 alkynyl, C.sub.2-C.sub.12 alkynyloxy, C.sub.3-C.sub.12 aryl and C.sub.3-C.sub.12 aryloxy, n represents an integer of 0, 1 or 2, wherein two or more of R.sup.4, R.sup.5, R.sup.6 and R.sup.7 may be bound to each other to form one or more rings and M represents a cation selected from Li, Na, K and ammonium, in Formula (iii) R.sup.8 represents a fluorine-containing counter-ion, and (b) irradiating the resulting mixture with visible light, wherein the method is carried out in the absence of a photosensitizer and external oxidant.

2. The method according to claim 1, wherein the boron-containing compound of Formula (i) is selected from a compound represented by the following Formulae (i-1) to (i-4): ##STR00066## wherein Ar.sup.1 is as defined above, in Formula (i-1) each R.sup.9 is independently selected from hydrogen, C.sub.1-C.sub.12 alkyl, C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12 alkynyl and C.sub.3-C.sub.12 aryl, and wherein both R.sup.9 may be bound to each other to form a ring, in Formula (i-2) each R.sup.10 is independently selected from H, C.sub.1-C.sub.12 alkyl, C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12 alkynyl and C.sub.3-C.sub.12 aryl, wherein two or all of R.sup.10 may be bound to each other to form one or more rings and M represents a cation selected from Li, Na, K and ammonium, in Formula (i-3) each R.sup.11 is independently selected from C.sub.1-C.sub.12 alkyl, C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12 alkynyl and C.sub.3-C.sub.12 aryl, and wherein both R.sup.11 may be bound to each other to form a ring, and in Formula (i-4) each X is independently selected from halogen and M represents a cation selected from Li, Na, K and ammonium.

3. The method according to claim 1, wherein the boron-containing compound of Formula (i) is selected from a compound represented by the following Formulae (i-1-1) to (i-4-1): ##STR00067## ##STR00068## wherein Ar.sup.1 is as defined above, in Formula (i-1-3) each R.sup.12 is independently selected from hydroxy, amino, halogen, C.sub.1-C.sub.12 alkyl, C.sub.1-C.sub.11 alkoxy, C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12 alkenyloxy, C.sub.2-C.sub.12 alkynyl, C.sub.2-C.sub.12 alkynyloxy, C.sub.3-C.sub.12 aryl and C.sub.3-C.sub.12 aryloxy, wherein n represents an integer of 0 to 4 and one or more of R.sup.12 may be bound to each other to form one or more rings, in Formula (i-1-6) each R.sup.13 is independently selected from hydrogen, C.sub.1-C.sub.12 alkyl, C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12 alkynyl, and C.sub.3-C.sub.12 aryl, and wherein both R.sup.13 may be bound to each other to form a ring, and in Formulae (i-2-1) and (i-4-1) M represents a cation selected from Li, Na, K and ammonium.

4. The method according to claim 1, wherein the silicon-containing compound of Formula (ii) is selected from a compound represented by the following Formula (ii-1) to (ii-4): ##STR00069## wherein Ar.sup.1 is as defined above, in Formula (ii-1) each R.sup.11 is independently selected from H, C.sub.1-C.sub.11 alkyl, C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12 alkynyl and C.sub.3-C.sub.12 aryl, each R.sup.15 is independently selected from H, hydroxy, halogen, amino, C.sub.1-C.sub.12 alkyl, C.sub.1-C.sub.12 alkoxy, C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12 alkenoxy, C.sub.2-C.sub.12 alkynyl, C.sub.2-C.sub.12 alkynoxy, C.sub.3-C.sub.12 aryl and C.sub.3-C.sub.12 aryloxy, wherein two or more of R.sup.14 and R.sup.15 may be bound to each other to form one or more rings and n represents an integer of 0 to 3, in Formula (ii-2) each R.sup.16 is independently selected from H, C.sub.1-C.sub.11 alkyl, C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12 alkynyl and C.sub.3-C.sub.12 aryl, each R.sup.17 is independently selected from H, hydroxy, halogen, amino, C.sub.1-C.sub.12 alkyl, C.sub.1-C.sub.12 alkoxy, C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12 alkenoxy, C.sub.2-C.sub.12 alkynyl, C.sub.2-C.sub.12 alkynoxy, C.sub.3-C.sub.12 aryl and C.sub.3-C.sub.12 aryloxy, wherein two or more of R.sup.16 and R.sup.17 may be bound to each other to form one or more rings and n represents an integer of 0 to 4, in Formula (ii-3) each R.sup.18 and R.sup.19 is independently selected from H, hydroxy, halogen, amino, C.sub.1-C.sub.12 alkyl, C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12 alkynyl and C.sub.3-C.sub.12 aryl, and wherein two or more of R.sup.18 and R.sup.19 may be bound to each other to form one or more rings, in Formula (ii-4) each R.sup.20 is independently selected from H, hydroxy, halogen, amino, C.sub.1-C.sub.12 alkyl, C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12 alkynyl and C.sub.3-C.sub.12 aryl, wherein two or more of R.sup.20 may be bound to each other to form one or more rings and M represents a cation selected from Li, Na, K and ammonium, and in Formula (ii-5) each R.sup.11 is independently selected from H, hydroxy, halogen, amino, C.sub.1-C.sub.12 alkyl, C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12 alkynyl and C.sub.3-C.sub.12 aryl, wherein two or more of R.sup.21 may be bound to each other to form one or more rings and each M independently represents a cation selected from Li, Na, K and ammonium.

5. The method according to claim 1, wherein the silicon-containing compound of Formula (ii) is selected from a compound represented by the following Formulae (ii-1-1) to (ii-5-1): ##STR00070## wherein Ar.sup.1 is as defined above, in Formula (ii-2-1) each R.sup.22 is independently selected from hydroxy, amino, halogen, C.sub.1-C.sub.12 alkyl, C.sub.1-C.sub.11 alkoxy, C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12 alkenyloxy, C.sub.2-C.sub.12 alkynyl, C.sub.2-C.sub.12 alkynyloxy, C.sub.3-C.sub.12 aryl and C.sub.3-C.sub.12 aryloxy, wherein n represents an integer of 0 to 4, one or more of R.sup.22 may be bound to each other to form one or more rings and M represents a cation selected from Li, Na, K and ammonium, in Formula (ii-3-6) X represents halogen and n represents an integer of 1 to 4, in Formula (ii-4-1) each R.sup.23 is independently selected from hydroxy, amino, halogen, C.sub.1-C.sub.12 alkyl, C.sub.1-C.sub.11 alkoxy, C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12 alkenyloxy, C.sub.2-C.sub.12 alkynyl, C.sub.2-C.sub.12 alkynyloxy, C.sub.3-C.sub.12 aryl and C.sub.3-C.sub.12 aryloxy, X represents halogen, wherein one or more of R.sup.23 may be bound to each other to form one or more rings and M represents a cation selected from Li, Na, K and ammonium, and in Formula (ii-5-1) X represents halogen and each M represents a cation selected from Li, Na, K and ammonium.

6. The method according to claim 1, wherein R.sup.8 is selected from BF.sub.4, PF.sub.6, SbF.sub.6, OTf, NTf.sub.2, OSO.sub.2C.sub.4F.sub.9, F, OSO.sub.2F, BArF.sub.20, BArF.sub.24, brosylate, carborane, C(TF).sub.3, B(Ph).sub.4, Altebat, Bortebat, PFTB, and C(CF.sub.3).sub.4.

7. The method according to claim 1, wherein the aryl groups Ar.sup.1 and Ar.sup.2 are independently selected from furanyl, pyrrolyl, thiophenyl, imidazolyl, pyrazolyl, oxazolyl, isoxazolyl, thiazolyl, phenyl, pyridinyl, pyrazinyl, pyrimidinyl, pyradizinyl, benzofuranyl, indolyl, benzothiophenyl, benzimidazolyl, indazolyl, benzoxazolyl, benzisoxazolyl, benzothiazolyl, isobenzofuranyl, isoindolyl, purinyl, naphthyl, chinolinyl, chinoxalinyl and chinazolinyl.

8. The method according to claim 1, wherein each of the aryl groups Ar.sup.1 and Ar.sup.2 of the boron- or silicon-containing aryl compounds and the aryldiazonium compound, respectively, comprises one or more substituents which are independently selected from the group consisting of hydrogen, halogen, nitro, hydroxy, cyano, carboxyl, C.sub.1-C.sub.6 carboxylic acid ester, C.sub.1-C.sub.6 ether, C.sub.1-C.sub.6 aldehyde, C.sub.1-C.sub.6 ketone, sulfonyl, C.sub.1-C.sub.6 alkylsulfonyl, C.sub.1-C.sub.6 alkyl, C.sub.1-C.sub.6 haloalkyl, C.sub.1-C.sub.8 cycloalkyl, C.sub.1-C.sub.8 halocycloalkyl, C.sub.1-C.sub.8 heterocycloalkyl, C.sub.1-C.sub.6 alkoxy, C.sub.1-C.sub.6 haloalkoxy, C.sub.3-C.sub.12 aryl, C.sub.3-C.sub.12 heteroaryl and spiro-groups.

9. The method according to claim 1, wherein the gold(I) catalyst is selected from the group consisting of (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl, Ph.sub.3PAuNTf.sub.2, Cy.sub.3PAuCl, (4-Me-C.sub.6H.sub.4).sub.3PAuCl and (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuNTf.sub.2.

10. The method according to claim 1, wherein the solvent is selected from the group consisting of MeOH, EtOH, and MeCN.

11. The method according to claim 1, wherein the method is further carried out in the absence of an external ligand and/or additives in general.

12. The method according to claim 1, wherein irradiation in step (b) is carried out at a temperature of 0 to 60 C. for a duration of 10 min. to 24 hours.

13. (canceled)

14. (canceled)

15. A method for manufacturing optionally functionalized biaryl compounds, comprising: (a) providing (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl, Ph.sub.3PAuNTf.sub.2, Cy.sub.3PAuCl, (4-Me-C.sub.6H.sub.4).sub.3PAuCl or (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuNTf.sub.2 as a catalyst to a mixture containing a boron-containing aryl compound or a silicon-containing aryl compound; and (b) irradiating the resulting mixture with visible light, wherein the method is carried out in the absence of a photosensitizer and external oxidant.

Description

[0082] The figures show:

[0083] FIG. 1 shows Left: The photoreactor which is equipped with 29 W LED stripes (.sub.max=470 nm) and a fan on top to keep the reactor in a temperature range of 0 to 60 C., preferably around room temperature, during the reaction processes. Right: Reaction mixture before irradiation with blue LEDs (left), reaction mixture after irradiation with blue LEDs for 16 h (right).

[0084] FIG. 2 shows a graph wherein the slope equals the quantum yield () of the photoreaction. =0.3021 (=30.2%).

[0085] The following examples are intended to further illustrate the present invention. However, the present invention is not limited to these specific examples.

EXAMPLES

1. General Information

[0086] All commercially available chemicals were purchased from suppliers (ABCR, Acros, Alfa Aesar, Chempur, Merck and Sigma Aldrich) or obtained from the chemical store of the University of Heidelberg and were used without further purifications. Dry solvents were dispensed from solvent purification system MB SPS-800-Benchtop. Deuterated solvents were supplied from Euriso-Top and used as received. The NMR spectra, if not noted otherwise, were recorded at room temperature on the following spectrometers: Bruker Avance III 300 (300 MHz), Bruker Avance DRX 300 (300 MHz), Bruker Avance III 400 (400 MHz), Bruker Avance III 500 (500 MHz), Bruker Avance III 600 (600 MHz) or Fourier 300 (300 MHz). Chemical shifts 6 are quoted in parts per million (ppm) and coupling constants J in hertz (Hz). .sup.1H and .sup.13C spectra are calibrated in relation to the deuterated solvents, namely CDCl.sub.3 (7.26 ppm; 77.16 ppm). .sup.31P spectra were calibrated in relation to the reference measurement of phosphoric acid (0.00 ppm). .sup.19F spectra were calibrated in relation to the reference measurement of 1,2-difluorobenze (139 ppm). The following abbreviations were used to indicate the signal multiplicity: for the .sup.1H NMR spectra: s (singlet), d (doublet), t (triplet), q (quartet), quint (quintet), sext (sextet), sept (septet), m (multiplet), as well as their combinations; for the .sup.13C NMR spectra: s (quaternary carbon), d (tertiary carbon (CH)), t (secondary carbon (CH.sub.2)) and q (primary carbon (CH.sub.3)). All the .sup.13C NMR spectra were measured with .sup.1H-decoupling and were interpreted with the help of DEPT135, .sup.1H,.sup.1HCOSY and HMBC. All spectra were integrated and processed using TopSpin 3.5 software. Mass spectra (MS and HRMS) were determined in the chemistry department of the University Heidelberg under the direction of Dr. J. Gross. Elk-spectra were measured on a JOEL JMS-700 spectrometer. For ESI.sup.+-spectra a Bruker ApexQu FT-ICR-MS spectrometer was applied. Gas chromatography/Mass Spectroscopy (GC MS) were carried out on two different systems: 1. HP 5972 Mass Selective Detector, coupled with a HP 5890 SERIES II plus Gas Chromatograph. 2. Agilent 5975C Mass Selective Detector, coupled with an Agilent 7890A Gas Chromatograph. In both cases, as a capillary column, an OPTIMA 5 cross-linked Methyl Silicone column (30 m, 0.32 mm, 0.25 mm) was employed, and helium was used as the carrier gas. Flash Column Chromatography was accomplished using Silica gel 60 (0.04-0.063 mm/230-400 mesh ASTM) purchased from Macherey-Nagel as stationary phase. As eluents the respectively mentioned proportions of petroleum ether (PE) and ethyl acetate (EA) were used. Analytical Thin Layer Chromatography (TLC) was carried out on precoated Macherey-Nagel POLYGRAM SIL G/UV254 or Merck TLC Silical Gel 60 F254 aluminium sheets. Detection was accomplished using UV-light (254 nm), KMnO.sub.4 (in 1.5M Na.sub.2CO.sub.3 (aq.)), molybdatophosphoric acid (5% in ethanol), vanillin/H.sub.2SO.sub.4 (in ethanol) or anisaldehyde/HOAc (in ethanol).

[0087] The aryldiazonium tetrafluoroborates were synthesized according to a modified procedure reported by Knig et al. (D. P. Hari, P. Schroll, B. Knig, J. Am. Chem. Soc. 2012, 134, 2968-2961). The neutral gold complexes were prepared after a procedure published by Hashmi et al. (L. Huang, M. Rudolph, F. Rominger, A. S. K. Hashmi, Angew. Chem. Int. Ed. 2016, 55, 4808-4813) and the synthesis of the cationic gold complexes proceeded after a modification of a literature report by Ogawa et al. (T. Tamai, K. Fujiwara, S. Higashimae, A. Nomoto, A. Ogawa, Org. Lett. 2016, 18, 2114-2117).

2. General Procedures

2.1 General Procedure for the Synthesis of Aryldiazonium Tetrafluoroborate (GP1)

[0088] ##STR00030##

[0089] The corresponding aniline (10 mmol, 1.0 equiv.) was dissolved in a mixture of water (3.5 mL) and 3.5 mL of a 48 wt. % tetrafluoroboric acid solution in H.sub.2O. After cooling to 0 C. an aqueous solution of sodium nitrite (690 mg, 10 mmol, 1.0 equiv., in 1.0 mL H.sub.2O) was added dropwise over a course of 10 min. The reaction mixture was stirred for 30 min and the resulting precipitate was collected by filtration. The crude product was purified by dissolving in a minimum amount of acetone. The product was precipitated by addition of Et.sub.2O, which was again collected by filtration. For further purification this can be repeated several times. After drying under high vacuum the corresponding diazonium tetrafluoroborate was obtained and stored at 20 C.

2.2 General Procedure for the Synthesis of Gold Complexes (GP2)

[0090] DMSAuCl (1.0 equiv.) was dissolved in DCM (10 mol/l) and the corresponding ligand (1.0 equiv.) was added. After stirring for 2 hours at room temperature in the dark, the solvent was removed under reduced pressure at room temperature in the dark. The crude product was purified by dissolving in a minimum amount of DCM and the gold complex was precipitated by addition of n-pentane or PE. After filtration and drying under high vacuum in the dark, the corresponding gold complex was obtained and stored at 20 C.

2.3 General Procedure for the Synthesis of Cationic Gold Complexes (GP3)

[0091] The corresponding gold complex of GP2 (1.0 equiv.) was dissolved in DCM (40 mmol/l) and AgNTf.sub.2 (1.0 equiv.) was added. After the reaction mixture was stirred for 15 min at room temperature, the precipitated AgCl was removed by filtration through a Celite Pad. The filtrate was concentrated under reduced pressure and the obtained cationic gold complex was dried under high vacuum.

2.4 General Procedure for Visible-Light-Mediated Gold Catalyzed C(Sp.SUP.2.)C(Sp.SUP.2.)-Coupling (GP4)

[0092] ##STR00031##

[0093] In a dried Pyrex screw-top reaction tube (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 10 mol %) and the corresponding boronic acid (0.3 mmol, 1.0 equiv.) were dissolved in 1.5 mL MeOH. After adding the corresponding diazonium salt (1.2 mmol, 4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated at room temperature with 29 W blue LEDs for 15-17 hours. The solvent was removed under reduced pressure and the resulting crude product was purified by column chromatography on SiO.sub.2.

2.5 General Procedure for Visible-Light-Mediated Gold Catalyzed C(Sp.SUP.2.)C(Sp.SUP.2.)-Coupling Using BPin as the Coupling Partner (GP5)

[0094] ##STR00032##

[0095] In a dried Pyrex screw-top reaction tube (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.01 mmol, 10 mol %) and the corresponding boronic pinacol ester (0.1 mmol, 1.0 equiv.) were dissolved in 0.5 mL MeOH. After adding the corresponding diazonium salt (0.4 mmol, 4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated at room temperature with 29 W blue LEDs for 16 hours. The solvent was removed under reduced pressure and the resulting crude product was purified by preparative TLC.

3. Optimization of Model Reaction

[0096]

TABLE-US-00002 TABLE 2 Screening of photocatalyst..sup.[a] [00033] Entry Catalyst (10 mol- %) Solvent T [ C.] Light source Additives Yield [%] 1 Ph.sub.3PAuCl MeCN r.t Blue LEDs traces.sup.[d] 2 (4-FC.sub.6H.sub.4).sub.3PAuCl MeCN r.t Blue LEDs traces.sup.[d] 3 (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl MeCN r.t Blue LEDs 51.sup.[c] 4 (4-MeC.sub.6H.sub.4).sub.3PAuCl MeCN r.t Blue LEDs 20.sup.[c] 5 Ph.sub.2qnPAuCl MeCN r.t Blue LEDs traces.sup.[d] 6 Cy.sub.3PAuCl MeCN r.t Blue LEDs 31.sup.[c] 7 Ph.sub.3PAuNtf.sub.2 MeCN r.t Blue LEDs 31.sup.[c] 8 (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuNtf.sub.2 MeCN r.t Blue LEDs 22.sup.[c] 9 RO.sub.3PAuCl[b] MeCN r.t Blue LEDs ND.sup.[d] .sup.[a]Reaction conditions: 4-methoxycarbonylphenyl boronic acid (1, 0.1 mmol), phenyldiazonium salt (2, 0.4 mmol) and gold catalyst (10 mol %) were reacted in 0.5 mL MeCN at room temperature under irradiation with blue LED. [b]R = 1,3-di-tert-butylbenzene. .sup.[c]Yield of isolated product using PTLC. .sup.[d]Not detected, determined using GC-MS.

TABLE-US-00003 TABLE 3 Screening of solvent..sup.[a] [00034] Entry Catalyst (10 mol- %) Solvent T [ C.] Light source Additives Yield [%] 1 (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl MeCN r.t Blue LEDs 51.sup.[b] 2 (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl DMF r.t Blue LEDs ND.sup.[c] 3 (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl MeOH r.t Blue LEDs 85.sup.[b] 4 (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl THF r.t Blue LEDs ND.sup.[c] 5 (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl DCM r.t Blue LEDs ND.sup.[c] 6 (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl MeCN r.t Blue LEDs 2 equiv. 21.sup.[b] H2O .sup.[a]Reaction conditions: 4-methoxycarbonylphenyl boronic acid (1, 0.1 mmol), phenyldiazonium salt (2, 0.4 mmol) and gold catalyst (10 mol %) were reacted with different solvents at room temperature under irradiation with blue LED. .sup.[b]Yield of isolated product using PTLC. .sup.[c]Not detected, determined using GC-MS.

TABLE-US-00004 TABLE 4 Screening of different light sources and temperatures..sup.[a] [00035] Entry Catalyst (10 mol- %) Solvent T [ C.] Light source Additives Yield [%] 1 (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl MeOH r.t Blue LED 85.sup.[b] 2 (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl MeOH r.t dark ND.sup.[c] 3 (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl MeOH 70 C. CFL ND.sup.[c] 4 (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl MeOH 70 C. dark ND.sup.[c] 5 (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl MeOH 50 C. dark ND.sup.[c] 6 (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl MeOH r.t UVA 61.sup.[b] 7 (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl MeOH r.t UV-light[e] 75.sup.[b] .sup.[a]Reaction conditions: 4-methoxycarbonylphenyl boronic acid (1, 0.1 mmol), phenyldiazonium salt (2, 0.4 mmol) and gold catalyst (10 mol %) were reacted in 0.5 mL of MeOH with different light sources temperatures. .sup.[b]Yield of isolated product using PTLC. .sup.[c]Not detected, determined using GC-MS. [d] = 350 nm. [e] = 420 nm.

TABLE-US-00005 TABLE 5 Variation of equivalents of 2 and gold catalyst (4-CF.sub.3-C.sub.6H.sub.4).sub.3PAuCl..sup.[a][b] [00036] Diazonium Entry Catalyst x mol % Solvent T [ C.] Light source Additives salt x equiv. Yield [%] 1 10 MeOH r.t Blue LEDs 1 21 2 10 MeOH r.t Blue LEDs 2 54 3 10 MeOH r.t Blue LEDs 3 56 4 10 MeOH r.t Blue LEDs 4 85 5 5 MeOH r.t Blue LEDs 4 47 6 MeOH r.t Blue LEDs 4 ND.sup.[c] .sup.[a]Reaction conditions: 4-methoxycarbonylphenyl boronic acid (1, x mmol), phenyldiazonium salt (2, 0.4 mmol) and gold catalyst (x mol %) were reacted in methanol at room temperature under irradiation with blue LED. .sup.[b]Yield of isolated product using PTLC. .sup.[c]Not detected, determined using GC-MS.

4. Synthesis and Characterization of Cross-Coupled Substituted Biaryls

4.1 Synthesis of Methyl[1,1-biphenyl]-4-carboxylate

[0097] ##STR00037##

[0098] According to GP4, (4-(methoxycarbonyl)phenyl)boronic acid (0.3 mmol, 54.0 mg, 1.0 equiv.) and (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 21.0 mg, 10 mol %) were dissolved in 1.5 mL MeOH. After adding benzenediazonium tetrafluoroborate (1.2 mmol, 230 mg, 4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated at room temperature with blue LEDs for 17 h and the crude product was purified by flash column chromatography (SiO.sub.2, PE/EA, 300:1) to give 53.2 mg of 3a (0.25 mmol, 84%) as a pale yellow solid. .sup.1H NMR (300 MHz, CDCl.sub.3): =3.90 (s, 3H), 7.33-7.46 (m, 3H), 7.58-7.70 (m, 4H) ppm, 8.05-8.09 (m, 2H).

4.2 Synthesis of 4-(trifluoromethyl)-1,1-biphenyl

[0099] ##STR00038##

[0100] According to GP4, (4-(trifluoromethyl)phenyl)boronic acid (0.3 mmol, 57.0 mg, 1.0 equiv.) and (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 21.0 mg, 10 mol %) were dissolved in 1.5 mL MeOH. After adding benzenediazonium tetrafluoroborate (1.2 mmol, 230 mg, 4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated room temperature with blue LEDs for 16 h and the crude product was purified by flash column chromatography (SiO.sub.2, PE/EA, 200:1) to give 45.1 mg of 3b (0.20 mmol, 68%) as a white solid. .sup.1H NMR (400 MHz, CDCl.sub.3): =7.39-7.43 (m, 1H), 7.46-7.50 (m, 2H), 7.60-7.62 (m, 2H), 7.70 (s, 4H) ppm.

4.3 Synthesis of 1-([1,1-biphenyl]-4-yl)ethan-1-one

[0101] ##STR00039##

[0102] According to GP4, (4-acetylphenyl)boronic acid (0.3 mmol, 49.2 mg, 1.0 equiv.) and (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 21.0 mg, 10 mol %) were dissolved in 1.5 mL MeOH. After adding benzenediazonium tetrafluoroborate (1.2 mmol, 230 mg, 4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated room temperature with blue LEDs for 16 h and the crude product was purified by flash column chromatography (SiO.sub.2, PE/EA, 500:1) to give 34.3 mg of 3c (0.18 mmol, 59%) as a white solid. .sup.1H NMR (300 MHz, CDCl.sub.3): =2.64 (s, 3H), 7.44-7.50 (m, 3H), 7.61-7.71 (m, 4H), 8.01-8.05 (m, 2H) ppm.

4.4 Synthesis of [1,1-biphenyl]-4-carbonitrile

[0103] ##STR00040##

[0104] According to GP4, (4-cyanophenyl)boronic acid (0.3 mmol, 44.1 mg, 1.0 equiv.) and (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 21.0 mg, 10 mol %) were dissolved in 1.5 mL MeOH. After adding benzenediazonium tetrafluoroborate (1.2 mmol, 230 mg, 4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated room temperature with blue LEDs for 16 h and the crude product was purified by flash column chromatography (SiO.sub.2, 100% PE) to give 31.2 mg of 3d (0.17 mmol, 58%) as a white solid. .sup.1H NMR (300 MHz, CDCl.sub.3): =7.41-7.52 (m, 3H), 7.57-7.61 (m, 2H), 7.67-7.75 (m, 4H) ppm.

4.5 Synthesis of 4-(methylsulfonyl)-1,1-biphenyl

[0105] ##STR00041##

[0106] According to GP4, (4-(methylsulfonyl)phenyl)boronic acid (0.3 mmol, 60.0 mg, 1.0 equiv.) and (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 21.0 mg, 10 mol %) were dissolved in 1.5 mL MeOH. After adding benzenediazonium tetrafluoroborate (1.2 mmol, 230 mg, 4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated room temperature with blue LEDs for 16 h and the crude product was purified by flash column chromatography (SiO.sub.2, PE/EA, 300:1-10:1) to give 43.2 mg of 3e (0.19 mmol, 62%) as an off white solid. .sup.1H NMR (400 MHz, CDCl.sub.3): =3.09 (s, 3H), 7.41-7.51 (m, 3H), 7.60-7.62 (m, 2H), 7.76-7.79 (m, 2H), 7.99-8.04 (m, 2H) ppm.

4.6 Synthesis of 3-phenylthiophene-2-carbaldehyde

[0107] ##STR00042##

[0108] According to GP4, (2-formylthiophen-3-yl)boronic acid (0.3 mmol, 46.8 mg, 1.0 equiv.) and (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 21.0 mg, 10 mol %) were dissolved in 1.5 mL MeOH. After adding benzenediazonium tetrafluoroborate (1.2 mmol, 230 mg, 4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated room temperature with blue LEDs for 16 h and the crude product was purified by flash column chromatography (SiO.sub.2, PE/EA, 20:1) to give 25.4 mg of 3f (0.14 mmol, 45%) as a pale yellow solid. .sup.1H NMR (400 MHz, CDCl.sub.3): =7.38-7.46 (m, 4H), 7.66-7.69 (m, 2H) ppm, 7.74 (d, J=3.9 Hz, 1H), 9.90 (s, 1H) ppm.

4.7 Synthesis of 4-fluoro-1,1-biphenyl

[0109] ##STR00043##

[0110] According to GP4, (4-fluorophenyl)boronic acid (0.3 mmol, 42.0 mg, 1.0 equiv.) and (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 21.0 mg, 10 mol %) were dissolved in 1.5 mL MeOH. After adding benzenediazonium tetrafluoroborate (1.2 mmol, 230 mg, 4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated room temperature with blue LEDs for 15 h and the crude product was purified by flash column chromatography (SiO.sub.2, 100% PE) to give 24.8 mg of 3g (0.15 mmol, 48%) as a white solid. .sup.1H NMR (300 MHz, CDCl.sub.3): =7.10-7.16 (m, 2H), 7.31-7.37 (m, 1H) ppm, 7.41-7.47 (m, 2H), 7.52-7.59 (m, 4H) ppm.

4.8 Synthesis of 4-chloro-1,1-biphenyl

[0111] ##STR00044##

[0112] According to GP4, (4-chlorophenyl)boronic acid (0.3 mmol, 47.0 mg, 1.0 equiv.) and (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 21.0 mg, 10 mol %) were dissolved in 1.5 mL MeOH. After adding benzenediazonium tetrafluoroborate (1.2 mmol, 230 mg, 4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated room temperature with blue LEDs for 16 h and the crude product was purified by flash column chromatography (SiO.sub.2, PE/EA, 500:1) to give 49.7 mg of 3h (0.26 mmol, 88%) as a white solid. .sup.1H NMR (300 MHz, CDCl.sub.3): =7.33-7.47 (m, 5H), 7.50-7.62 (m, 4H) ppm.

4.9 Synthesis of 4-bromo-1,1-biphenyl

[0113] ##STR00045##

[0114] According to GP4, (4-bromophenyl)boronic acid (0.3 mmol, 60.2 mg, 1.0 equiv.) and (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 21.0 mg, 10 mol %) were dissolved in 1.5 mL MeOH. After adding benzenediazonium tetrafluoroborate (1.2 mmol, 230 mg, f4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated room temperature with blue LEDs for 18 h and the crude product was purified by flash column chromatography (SiO.sub.2, 100% PE) to give 55.8 mg of 3i (0.26 mmol, 80%) as an off white solid. .sup.1H NMR (300 MHz, CDCl.sub.3): =7.34-7.48 (m, 5H), 7.54-7.58 (m, 4H) ppm.

4.10 Synthesis of 4-methoxy-1,1-biphenyl

[0115] ##STR00046##

[0116] According to GP4, (4-methoxyphenyl)boronic acid (0.3 mmol, 45.6 mg, 1.0 equiv.) and (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 21.0 mg, 10 mol %) were dissolved in 1.5 mL MeOH. After adding benzenediazonium tetrafluoroborate (1.2 mmol, 230 mg, 4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated room temperature with blue LEDs for 17 h and the crude product was purified by flash column chromatography (SiO.sub.2, PE/EA, 150:1) to give 12.1 mg of 3j (0.07 mmol, 23%) as a yellow solid. .sup.1H NMR (300 MHz, CDCl.sub.3): =3.86 (s, 3H), 6.96-7.01 (m, 2H), 7.27-7.33 (m, 1H), 7.39-7.44 (m, 2H), 7.51-7.57 (m, 4H) ppm.

4.11 Synthesis of methyl[1,1-biphenyl]-3-carboxylate

[0117] ##STR00047##

[0118] According to GP4, (3-(methoxycarbonyl)phenyl)boronic acid (0.3 mmol, 54.0 mg, 1.0 equiv.) and (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 21.0 mg, 10 mol %) were dissolved in 1.5 mL MeOH. After adding benzenediazonium tetrafluoroborate (1.2 mmol, 230 mg, 4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated room temperature with blue LEDs for 15 h and the crude product was purified by flash column chromatography (SiO.sub.2, PE/EA, 150:1) to give 26.3 mg of 3k (0.12 mmol, 41%) as a colorless oil. .sup.1H NMR (300 MHz, CDCl.sub.3): =3.95 (s, 3H), 7.36-7.41 (m, 1H), 7.44-7.54 (m, 3H), 7.61-7.65 (m, 2H), 7.77-7.81 (m, 1H), 8.01-8.05 (m, 1H), 8.29 (t, J=1.7 Hz, 1H) ppm.

4.12 Synthesis of methyl[1,1-biphenyl]-2-carboxylate

[0119] ##STR00048##

[0120] According to GP4, (2-(methoxycarbonyl)phenyl)boronic acid (0.3 mmol, 54.0 mg, 1.0 equiv.) and (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 21.0 mg, 10 mol %) were dissolved in 1.5 mL MeOH. After adding benzenediazonium tetrafluoroborate (1.2 mmol, 230 mg, 4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated room temperature with blue LEDs for 15 h and the crude product was purified by flash column chromatography (SiO.sub.2, PE/EA, 200:1) to give 42.8 mg of 3l (0.20 mmol, 67%) as a pale yellow oil. .sup.1H NMR (300 MHz, CDCl.sub.3): =3.65 (s, 3H), 7.31-7.45 (m, 7H), 7.44-7.54 (m, 3H), 7.61-7.65 (m, 2H), 7.54 (td, J=1.4 Hz, 7.6 Hz, 1H), 7.84 (dd, J=1.2 Hz, 7.6 Hz, 1H) ppm.

4.13 Synthesis of methyl 4-(trifluoromethyl)-[1,1-biphenyl]-4-carboxylate

[0121] ##STR00049##

[0122] According to GP4, (4-(methoxycarbonyl)phenyl)boronic acid (0.3 mmol, 54.0 mg, 1.0 equiv.) and (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 21.0 mg, 10 mol %) were dissolved in 1.5 mL MeOH. After adding 4-(trifluoromethyl)benzenediazonium tetrafluoroborate (1.2 mmol, 312 mg, 4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated room temperature with blue LEDs for 15 h and the crude product was purified by flash column chromatography (SiO.sub.2, PE/EA, 250:1) to give 68.8 mg of 3m (0.25 mmol, 82%) as a white solid. M.p=121-122 C. .sup.1H NMR (400 MHz, CDCl.sub.3): =3.95 (s, 3H), 7.65-7.68 (m, 2H), 7.72 (s, 4H), 8.12-8.15 (m, 2H) ppm. .sup.13C NMR (101 MHz, CDCl.sub.3): =52.2 (q), 125.9 (s, q: JC-F=3.8 Hz), 127.2 (d), 127.6 (d), 129.9 (s), 130.3 (d), 143.6 (s), 144.1 (s), 166.7 (s) ppm. .sup.19F NMR (283 MHz, CDCl.sub.3): =62.5 (s, 3F) ppm. IR (ATR): {tilde over (v)}=2954, 1943, 1712, 1609, 1584, 1437, 1398, 1373, 1334, 1287, 1182, 1158, 1143, 1111, 1075, 1023, 1008, 956, 869, 842, 833, 774, 739, 700, 667 cm-1 HR MS (EI (+)): m/z=280.0695, calcd. for [C.sub.15H.sub.11O.sub.2F.sub.3].sup.+: 280.0706.

4.14 Synthesis of methyl 4-fluoro-[1,1-biphenyl]-4-carboxylate

[0123] ##STR00050##

[0124] According to GP4, (4-(methoxycarbonyl)phenyl)boronic acid (0.3 mmol, 54.0 mg, 1.0 equiv.) and (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 21.0 mg, 10 mol %) were dissolved in 1.5 mL MeOH. After adding 4-fluorobenzenediazonium tetrafluoroborate (1.2 mmol, 252 mg, 4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated room temperature with blue LEDs for 16 h and the crude product was purified by flash column chromatography (SiO.sub.2, PE/EA, 200:1) to give 52.9 mg of 3n (0.23 mmol, 77%) as a white solid. .sup.1H NMR (600 MHz, CDCl.sub.3): =3.94 (s, 3H), 7.15 (t, J=8.6 Hz, 2H), 7.57-7.62 (m, 4H), 8.10 (d, J=8.2 Hz, 2H) ppm.

4.15 Synthesis of methyl 4-bromo-[1,1-biphenyl]-4-carboxylate

[0125] ##STR00051##

[0126] According to GP4, (4-(methoxycarbonyl)phenyl)boronic acid (0.3 mmol, 54.0 mg, 1.0 equiv.) and (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 21.0 mg, 10 mol %) were dissolved in 1.5 mL MeOH. After adding 4-bromobenzenediazonium tetrafluoroborate (1.2 mmol, 325 mg, 4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated room temperature with blue LEDs for 16 h and the crude product was purified by flash column chromatography (SiO.sub.2, PE/EA, 100:1) to give 83.1 mg of 3o (0.29 mmol, 95%) as a white solid. .sup.1H NMR (300 MHz, CDCl.sub.3): =3.95 (s, 3H), 7.47-7.50 (m, 2H), 7.57-7.64 (m, 4H), 8.09-8.12 (m, 2H) ppm.

4.16 Synthesis of methyl 4-chloro-[1,1-biphenyl]-4-carboxylate

[0127] ##STR00052##

[0128] According to GP4, (4-(methoxycarbonyl)phenyl)boronic acid (0.3 mmol, 54.0 mg, 1.0 equiv.) and (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 21.0 mg, 10 mol %) were dissolved in 1.5 mL MeOH. After adding 4-chlorobenzenediazonium tetrafluoroborate (1.2 mmol, 272 mg, 4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated room temperature with blue LEDs for 16 h and the crude product was purified by flash column chromatography (SiO.sub.2, PE/EA, 200:1) to give 63.8 mg of 3p (0.26 mmol, 84%) as an off white solid. .sup.1H NMR (300 MHz, CDCl.sub.3): =3.95 (s, 3H), 7.40-7.45 (m, 2H), 7.53-7.63 (m, 4H), 8.09-8.13 (m, 2H) ppm.

4.17 Synthesis of methyl 4-(tert-butyl)-[1,1-biphenyl]-4-carboxylate

[0129] ##STR00053##

[0130] According to GP4, (4-(methoxycarbonyl)phenyl)boronic acid (0.3 mmol, 54.0 mg, 1.0 equiv.) and (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 21.0 mg, 10 mol %) were dissolved in 1.5 mL MeOH. After adding 4-(tert-butyl)benzenediazonium tetrafluoroborate (1.2 mmol, 298 mg, 4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated room temperature with blue LEDs for 15 h and the crude product was purified by flash column chromatography (SiO.sub.2, PE/EA, 100:1) to give 61.8 mg of 3q (0.23 mmol, 77%) as an off white solid. .sup.1H NMR (300 MHz, CDCl.sub.3): =1.37 (s, 9H), 3.94 (s, 3H), 7.48-7.50 (m, 2H), 7.57-7.59 (m, 2H), 7.65-7.67 (m, 2H), 8.07-8.11 (m, 2H) ppm.

4.18 Synthesis of methyl 4-methoxy-[1,1-biphenyl]-4-carboxylate

[0131] ##STR00054##

[0132] According to GP4, (4-(methoxycarbonyl)phenyl)boronic acid (0.3 mmol, 54.0 mg, 1.0 equiv.) and (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 21.0 mg, 10 mol %) were dissolved in 1.5 mL MeOH. After adding 4-methoxybenzenediazonium tetrafluoroborate (1.2 mmol, 266 mg, 4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated room temperature with blue LEDs for 16 h and the crude product was purified by flash column chromatography (SiO.sub.2, PE/EA, 50:1) to give 21.7 mg of 3r (0.09 mmol, 30%) as a pale yellow solid. .sup.1H NMR (400 MHz, CDCl.sub.3): =3.87 (s, 3H), 3.94 (s, 3H), 6.98-7.02 (m, 2H), 7.56-7.64 (m, 4H), 8.07-8.11 (m, 2H) ppm.

4.19 Synthesis of methyl 4-(methylsulfonyl)-[1,1-biphenyl]-4-carboxylate

[0133] ##STR00055##

[0134] According to GP4, (4-(methoxycarbonyl)phenyl)boronic acid (0.3 mmol, 54.0 mg, 1.0 equiv.) and (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 21.0 mg, 10 mol %) were dissolved in 1.5 mL MeOH. After adding 4-(methylsulfonyl)benzenediazonium tetrafluoroborate (1.2 mmol, 324 mg, 4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated room temperature with blue LEDs for 17 h and the crude product was purified by flash column chromatography (SiO.sub.2, 100% DCM) to give 50.6 mg of 3s (0.17 mmol, 58%) as an off white solid. M.p=196-197 C. .sup.1H NMR (300 MHz, CDCl.sub.3): =3.10 (s, 3H), 3.96 (s, 3H), 7.68 (d, J=8.8 Hz, 2H), 7.80 (d, J=8.8 Hz, 2H), 8.04 (d, J=8.8 Hz, 2H), 8.16 (d, J=8.3 Hz, 2H) ppm. .sup.13C NMR (75 MHz, CDCl.sub.3): =44.5 (q), 52.2 (q), 127.3 (d), 128.0 (d), 128.1 (d), 130.2 (s), 130.3 (d), 139.9 (s), 143.3 (s), 145.4 (s), 166.5 (s) ppm. IR (ATR): G=3073, 3019, 2961, 2933 1946, 1925, 1715, 1608, 1580, 1561, 1456, 1440, 1396, 1311, 1294, 1273, 1214, 1196, 1181, 1150, 1117, 1096, 1021, 1005, 970, 867, 833, 784, 869, 751, 714, 699, 615 cm.1. HR MS (EI (+)): m/z=290.0599, calcd. for [C.sub.15H.sub.14O.sub.4S].sup.+: 290.0607.

4.20 Synthesis of methyl 3-(4-(methoxycarbonyl)phenyl)thiophene-2-carboxylate

[0135] ##STR00056##

[0136] According to GP4, (4-(methoxycarbonyl)phenyl)boronic acid (0.3 mmol, 54.0 mg, 1.0 equiv.) and (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 21.0 mg, 10 mol %) were dissolved in 1.5 mL MeOH. After adding 2-(methoxycarbonyl)-3-thiophenediazonium tetrafluoroborate (1.2 mmol, 306 mg, 4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated room temperature with blue LEDs for 15 h and the crude product was purified by flash column chromatography (SiO.sub.2, PE/EA, 150:1 till 50:1) to give 40.6 mg of 3t (0.15 mmol, 49%) as a white solid. M.p=127-128 C. .sup.1H NMR (400 MHz, CDCl.sub.3): =3.77 (s, 3H), 3.94 (s, 3H), 7.10 (d, J=5.0 Hz, 1H), 7.50-7.55 (m, 3H), 8.06-8.09 (m, 2H) ppm. .sup.13C NMR (101 MHz, CDCl.sub.3): b=52.0 (q), 52.1 (q), 127.8 (d), 129.1 (d), 129.3 (d), 129.5 (s), 130.5 (d), 131.2 (d), 133.3 (s), 140.4 (s), 147.3 (s), 162.2 (s), 166.9 (s) ppm. IR (ATR): {tilde over (v)}=3107, 3026, 2954, 2841, 1712, 1610, 1570, 1540, 1498, 1458, 1430, 1416, 1403, 1317, 1271, 1224, 1181, 1099, 1068, 1018, 966, 893, 865, 843, 819, 786, 763, 710, 700, 676, 654, 628 cm-1. HR MS (EI (+)): m/z=276.0437, calcd. for [C.sub.14H.sub.12O.sub.4S].sup.+: 276.0450.

4.21 Synthesis of methyl 4-acetyl-[1,1-biphenyl]-4-carboxylate

[0137] ##STR00057##

[0138] According to GP4, (4-(methoxycarbonyl)phenyl)boronic acid (0.3 mmol, 54.0 mg, 1.0 equiv.) and (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 21.0 mg, 10 mol %) were dissolved in 1.5 mL MeOH. After adding 4-acetylbenzenediazonium tetrafluoroborate (1.2 mmol, 281 mg, 4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated room temperature with blue LEDs for 17 h and the crude product was purified by flash column chromatography (SiO.sub.2, PE/DCM, 10:1) to give 56.7 mg of 3u (0.22 mmol, 75%) as a white solid. .sup.1H NMR (300 MHz, CDCl.sub.3): =2.65 (s, 3H), 3.95 (s, 3H), 7.68-7.74 (m, 4H), 8.04-8.08 (m, 2H), 8.12-8-16 (m, 2H) ppm.

4.22 Synthesis of methyl 3-fluoro-[1,1-biphenyl]-4-carboxylate

[0139] ##STR00058##

[0140] According to GP4, (4-(methoxycarbonyl)phenyl)boronic acid (0.3 mmol, 54.0 mg, 1.0 equiv.) and (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 21.0 mg, 10 mol %) were dissolved in 1.5 mL MeOH. After adding 3-fluorobenzenediazonium tetrafluoroborate (1.2 mmol, 252 mg, 4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated room temperature with blue LEDs for 16 h and the crude product was purified by flash column chromatography (SiO.sub.2, PE/EA, 150:1) to give 57.0 mg of 3v (0.25 mmol, 83%) as an off white solid. M.p=59-60 C. .sup.1H NMR (600 MHz, CDCl.sub.3): =3.94 (s, 3H), 7.07-7.10 (m, 1H), 7.32 (dt, J=1.9 Hz, J=9.9 Hz, 1H), 7.39-7.45 (m, 2H), 7.63-7.65 (m, 2H), 8.10-8.12 (m, 2H) ppm. .sup.13C NMR (151 MHz, CDCl.sub.3): =52.5 (q), 114.5 (d, d: JC-F=23.4 Hz), 115.3 (d, d: JC-F=21.0 Hz), 123.2 (d, d: JC-F=3.0 Hz), 127.4 (d), 129.8 (s), 130.5 (d), 130.7 (d, d: JC-F=8.5 Hz), 142.5 (s, d: JC-F=7.4 Hz), 144.5 (s, d: JC-F=2.3 Hz), 163.5 (s, d: JC-F=245.3 Hz), 167.2 (s) ppm. .sup.19F NMR (283 MHz, CDCl.sub.3): =112.7 (s, 1F) ppm. IR (ATR): {tilde over (V)}=3075, 3008, 2957, 2852, 1937, 1719, 1611, 1589, 1569, 1486, 1475, 1439, 1399, 1279, 1189, 1166, 1114, 1037, 1016, 1000, 961, 903, 881, 854, 828, 797, 770, 726, 700, 685, 648 cm-1. HR MS (EI (+)): m/z=230.0740, calcd. for [C.sub.14H.sub.11O.sub.2F].sup.+: 230.0743.

4.23 Synthesis of methyl 2-fluoro-[1,1-biphenyl]-4-carboxylate

[0141] ##STR00059##

[0142] According to GP4, (4-(methoxycarbonyl)phenyl)boronic acid (0.3 mmol, 54.0 mg, 1.0 equiv.) and (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 21.0 mg, 10 mol %) were dissolved in 1.5 mL MeOH. After adding 2-fluorobenzenediazonium tetrafluoroborate (1.2 mmol, 252 mg, 4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated room temperature with blue LEDs for 15 h and the crude product was purified by flash column chromatography (3102, PE/EA, 150:1) to give 45.3 mg of 3w (0.20 mmol, 66%) as a pale brown solid. M.p=61-62 C. .sup.1H NMR (600 MHz, CDCl.sub.3): =3.94 (s, 3H), 7.16-7.19 (m, 1H), 7.23 (td, J=1.0 Hz, J=7.5 Hz, 1H), 7.33-7.38 (m, 1H), 7.46 (td, J=1.7 Hz, J=7.7 Hz, 1H), 7.63 (dd, J=1.5 Hz, J=8.3 Hz, 2H), 8.10 (d, J=8.4 Hz, 2H) ppm. .sup.13C NMR (151 MHz, CDCl.sub.3): =52.5 (q), 116.5 (d, d: JC-F=23.8 Hz), 124.8 (d, d: JC-F=3.7 Hz), 128.3 (d, d: JC-F=12.8 Hz), 129.3 (d, d: JC-F=2.8 Hz), 129.5 (s), 130.0 (d), 130.1 (d, d: JC-F=8.3 Hz), 130.9 (s, d: JC-F=3.2 Hz), 140.7 (s), 160.0 (s, d: JC-F=247.2 Hz), 167.2 (s) ppm. .sup.19F NMR (283 MHz, CDCl.sub.3): =117.5 (s, 1F) ppm. IR (ATR): 9=3002, 2954, 2851, 1939, 1720, 1613, 1584, 1514, 1485, 1453, 1440, 1402, 1316, 1282, 1253, 1209, 1116, 1102, 1043, 1025, 1008, 972, 949, 873, 857, 832, 818, 777, 766, 756, 726, 703, 616 cm-1. HR MS (EI (+)): m/z=230.0722, calcd. for [C.sub.14H.sub.11O.sub.2F].sup.+: 230.0738.

4.24 Synthesis of methyl 4-methyl-[1,1-biphenyl]-4-carboxylate

[0143] ##STR00060##

[0144] According to GP4, (4-(methoxycarbonyl)phenyl)boronic acid (0.3 mmol, 54.0 mg, 1.0 equiv.) and (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 21.0 mg, 10 mol %) were dissolved in 1.5 mL MeOH. After adding 4-methylbenzenediazonium tetrafluoroborate (1.2 mmol, 247 mg, 4.0 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tubes were irradiated room temperature with blue LEDs for 16 h and the crude product was purified by flash column chromatography (SiO.sub.2, PE/EA, 200:1) to give 24.8 mg of 3 (0.11 mmol, 38%) as a pale yellow solid. .sup.1H NMR (300 MHz, CDCl.sub.3): =2.41 (s, 3H), 3.94 (s, 3H), 7.29 (s, 2H), 7.51-7.54 (d, J=8.2 Hz, 2H), 7.63-7.66 (m, 2H), 8.07-8.10 (m, 2H) ppm.

4.25 Synthesis of 4-iodo-1,1-biphenyl

[0145] ##STR00061##

[0146] The reaction was carried out according to GP4, using 74.3 mg of (4-iodophenyl)boronic acid (0.3 mmol, 1.0 equiv.), 21.0 mg of (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.03 mmol, 10 mol %), 230 mg of benzenediazonium tetrafluoroborate (1.2 mmol, 4.0 equiv.) and 1.5 mL of MeOH. After flash column chromatography (SiO.sub.2, 100% n-heptane), 68.0 mg of 3y (0.24 mmol, 81%) were isolated as a white solid. .sup.1H NMR (300 MHz, CDCl.sub.3): =7.33-7.39 (m, 3H), 7.44-7.47 (m, 2H), 7.55-7.57 (m, 1H), 7.60-7.62 (m, 1H), 7.76-7.79 (m, 2H) ppm. The data is consistent with literature values.

5. Mechanistic Studies

5.1 Control Experiments

[0147] ##STR00062##

Control Experiment A:

[0148] In a dried Pyrex screw-top reaction tube (4-(methoxycarbonyl)phenyl)boronic acid (0.1 mmol, 1.0 equiv.) was dissolved in 0.5 mL MeOH. After addition of benzenediazonium tetrafluoroborate (0.4 mmol, 0.4 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tube was irradiated with 29W blue LEDs for 16 h. The crude mixture was subjected to GC-MS analysis, no product 3a was detected. This observation was also confirmed by NMR spectroscopy, which shows that the presence of the catalyst is essential to the reaction.

Control Experiment B:

[0149] In a dried Pyrex screw-top reaction tube (4-(methoxycarbonyl)phenyl)boronic acid (0.1 mmol, 1.0 equiv.) was dissolved in 0.5 mL MeOH. After the reaction mixture was degassed under argon by sparging for 5-10 min, the tube was irradiated with 29W blue LEDs for 16 h. The crude mixture was analyzed by GC-MS and NMR spectroscopy, the intact boronic acid and the corresponding hydrogenated product, methyl benzoate, could be detected.

Control Experiment C:

[0150] In a dried Pyrex screw-top reaction tube (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.01 mmol, 10 mol %) and (4-(methoxycarbonyl)phenyl)boronic acid (0.1 mmol, 1.0 equiv.) were dissolved in 0.5 mL MeOH. After the reaction mixture was degassed under argon by sparging for 5-10 min, the tube was irradiated with 29W blue LEDs for 15 h. The solvent was removed under reduced pressure and the crude product was analyzed by .sup.1H NMR, .sup.11B NMR, .sup.31P NMR and .sup.19F NMR, which indicate an intact catalyst and boronic acid. This shows that the presence of the aryldiazonium salt is essential to the reaction.

Control Experiment D:

[0151] In a dried Pyrex screw-top reaction tube (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.01 mmol, 10 mol %) was dissolved in 0.5 mL MeOH. After addition of benzenediazonium tetrafluoroborate (0.4 mmol, 0.4 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tube was irradiated with 29W blue LEDs for 16 h. The crude mixture was subjected to GC-MS analysis which showed that homocoupling product was obtained.

5.2 Variation of the Counterion of the Aryldiazonium Salt

[0152] To answer the question whether the tetrafluoroborate anion plays an essential role in the reaction mechanism, a diazonium salt with bis((trifluoromethyl)sulfonyl)amide as the anion was synthesized. The synthesis was performed according to a procedure reported by Hass et al. (A. Haas, Y. L. Yagupolskii, C. Klare, Mendeleev Commun. 1992, 2, 70).

##STR00063##

##STR00064##

Experiment A:

[0153] In a dried Pyrex screw-top reaction tube (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.01 mmol, 10 mol %) and (4-(methoxycarbonyl)phenyl)boronic acid (0.1 mmol, 1.0 equiv.) were dissolved in 0.5 mL MeOH. After adding 4-bromobenzenediazonium bis((trifluoromethyl)sulfonyl)amide (0.4 mmol, 0.4 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tube was irradiated with 29 W blue LEDs for 15 hours. The crude mixture was subjected to GC-MS analysis, no product 3o was detected. This shows that the presence of a fluoride source, such as tetrafluoroborate, is essential for the reaction.

Experiment B:

[0154] In a dried Pyrex screw-top reaction tube (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (0.01 mmol, 10 mol %) and (4-(methoxycarbonyl)phenyl)boronic acid (0.1 mmol, 1.0 equiv.) were dissolved in 0.5 mL MeOH. After adding CsF (0.2 mmol, 2.0 equiv.) 4-bromobenzenediazonium bis((trifluoromethyl)sulfonyl)amide (0.4 mmol, 0.4 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The tube was irradiated with 29 W blue LEDs for 15 hours. The crude mixture was subjected to GC-MS analysis, product 3o was detected. The product was purified by pTLC (SiO.sub.2, PE/EA, 5:1) to give 10.5 mg of 3o (0.04 mmol, 36%). This shows, that adding an external fluoride source the reactions proceeds and the desired product can be formed.

5.3 Quantum Yield Measurement

[0155] The quantum yield () was determined by the known ferrioxolate actinometry method. A ferrioxolate actinometry solution was prepared by following the Hammond variation of the Hatchard and Parker procedure outlined in the Handbook of Photochemistry.[18] The irradiated light intensity was estimated to 3.0010.sup.7 Einstein S.sup.1 by using K.sub.3[Fe(C.sub.2O.sub.4).sub.3] as an actinometer.

[0156] Five dried Pyrex screw-top reaction tubes were each charged with (4-CF.sub.3C.sub.6H.sub.4).sub.3PAuCl (8.0 mol, 10 mol %), (4-(methoxycarbonyl)phenyl)boronic acid (0.08 mmol, 1.0 equiv.) and dodecane (0.08 mmol, 1.0 equiv.) and dissolved in 0.4 mL MeOH. After adding phenyldiazonium tetrafluoroborate (0.32 mmol, 0.4 equiv.) the reaction mixture was degassed under argon by sparging for 5-10 min. The solutions were irradiation with blue LEDs for specified time intervals (5 min, 10 min, 15 min, 20 min and 25 min). The moles of products formed were determined by GC-MS with dodecane as reference standard. The number of moles of products (y axis) per unit time is related to the number of photons (x axis, calculated from the light intensity). The slope of the graph represented in FIG. 2 equals the quantum yield () of the photoreaction. =0.3021 (=30.2%).