2-(Benzo[b]thiophen-5-yl)-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane

Dissolve 5-bromo-benzo [b] thiophene (J. Mater. Chem., 10: 2069-2081, 2000 ; 49 g, 7.0 mmol) in DMSO (40 mL). Add bis (pinacolato) diboron (7 mmol), PdCl2 (dppf)-CH2Cl2 (0.33 mmol), and KOAc (20 mmol). Flush the flask with N2, and then heat the reaction mixture to 80°C with stirring. Continue to heat the reaction mixture for 3 hours, and then cool to room temperature. Add water (66 mL) and extract the aqueous layer with EtOAc (3 x 66 mL). Combine the organic layers and dry with Na2SO4, filter, concentrate and purify by flash column chromatography (silica gel, 0-5percent Et20/pentane) to give 1.56 g of the title compound (86percent).Step E: Bis(pinacolato)diboron (1.3 g, 5.12 mmol), dichloro[1, 1'-bis(diphenylphosphino)ferrocene]palladium(II)dichloromethane (0.1 g, 0.14 mmol) and potassium acetate (1.4 g, 14.26 mmol) were charged in a 100 ml 3 neck round-bottomed flask which had been dried with a heat gun under vacuum and cooled under nitrogen prior to use. The mixture was degassed with nitrogen three times. A solution of 5-bromothiophene (1.0 g, 4.69 mmol) in dimethyl sulfoxide (20 ml) was added, the mixture was degassed again three times and was stirred at 85° C. for 1.5 hours. After cooling to room temperature, the mixture was filtered through diatomaceous earth and rinsed with water and ethyl acetate. Additional water was added to the filtrate which was extracted with ethyl acetate three times. The combined organic extracts were washed with brine once and dried over sodium sulfate to give the desired material (0.8 g, 64percent, 100percent AUC GC) after chromatography (9:1 to 5:1 heptane/ethyl acetate):

Molecular Weight:260.2
Hydrogen Bond Acceptor Count:3
Rotatable Bond Count:1
Exact Mass:260.1042311
Monoisotopic Mass:260.1042311
Topological Polar Surface Area:46.7
Heavy Atom Count:18
Complexity:316
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes