3-Ethynylpyridine → 3-[2-(4,4,5,5-Tetramethyl-[1,3,2]dioxaborolan-2-YL)-vinyl]-pyridine

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Reaction Conditions

Reaction Steps

Commercially available 3-ethynyl-pyridine 3b (1.03 g, 10 mmol) and 4,4,5,5-tetramethyl-[1,3,2]dioxaborolane (7.26 mL, 50 mmole) in toluene (40 mL) were combined with carbonylchlorohydridotris(triphenylphosphine) ruthenium (II), RuHCl(CO)(PPh3) (476 mg, 0.50 mmol) at ambient temperature and the reaction mixture was heated at 50° C. in an oil-bath for 16 h. The toluene was evaporated and the crude compound was diluted with ethyl acetate and washed with saturated sodium bicarbonate solution, saturated sodium chloride solution, and water. The organic extracts were dried over MgSO4, filtered, and evaporated in vacuo. The crude product was eluted with a gradient of 10:1 to 2:1 hexane/ethyl acetate by flash chromatography to yield 3-[2-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-vinyl]-pyridine Compound 3c (2.2 g, 95% yield) as a yellow syrup. 1H NMR (300 MHz, CDCl3) δ 8.75 (d, 1H), 8.54 (dd, 1H), 7.83 (dt, 1H), 7.39 (d, 1H), 7.31 (dd, 1H), 6.27 (d, 1H), 1.34 (s, 12H); MS (ESI) m/z: 232.14 (M+H+).

Provenance & Evidence