4,4,5,5-Tetramethyl[1,3,2]dioxaborolane → 5-Ethyl-2,2-diphenyl-4-[4-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-butyl]-oxazolidine-4-carboxylic acid tert-butyl ester

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Reaction Steps

A solution of 4-but-3-enyl-5-ethyl-2,2-diphenyl-oxazolidine-4-carboxylic acid tert-butyl ester (230 mg, 0.56 mmol) in dichloromethane (2 mL, 0.3 M) was added chlorotris (triphenylphosphine)rhodium(I) (60 mg, 0.065 mmol, 10 mol %) at room temperature. After stirring for 30 min, 4,4,5,5-Tetramethyl-1,3,2-dioxaborolane (200 μl, 1.3 mmol, 2 eq) was added to the reaction mixture and stirred overnight. After quenching the reaction with water (3 mL), the resulting solution was diluted with ethyl acetate and washed successively with water and saturated aqueous NaCl, dried over MgSO4, filtered and concentrated. Purification by MPLC (1-40% ethyl acetate in heptane) gave 5-Ethyl-2,2-diphenyl-4-[4-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-butyl]-oxazolidine-4-carboxylic acid tert-butyl ester (152 mg, 0.28 mmol, 50%).

Provenance & Evidence