反应详情

Following the same procedure for the preparation of pinacol boronates, the reaction of ethyl (S)-3-methyl-4-oxobutanoate (S)-3 (0.057 g, 0.40 mmol) with CrCl2 (0.39 g, 3.18 mmol), 2-(dichloromethyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane 5 (0.168 g, 0.80 mmol) and LiI (0.21 g, 1.59 mmol) in THF (6 mL) afforded, after purification by column chromatography (silica gel, 97:3 hexane/ethyl acetate), 69 mg (65%) of a colourless oil identified as ethyl (3S,4E)-3-methyl-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pent-4-enoate (S)-4.

1. customafforded
2. customafter purification by column chromatography (silica gel, 97:3 hexane/ethyl acetate), 69 mg (65%) of a colourless oil