Methanol → HCID 60023926, compound

Participants

Reaction Conditions

Reaction Steps

Vinylmagnesium bromide (1M soln in THF, 34.6 mL, 34.6 mmol) was added to a solution of (R)-tert-butyl 1-(methoxy(methyl)amino)-3-methyl-1-oxobutan-2-ylcarbamate (4.5 g, 17.30 mmol) in anhydrous tetrahydrofuran (50 mL) under nitrogen at −78° C., dropwise, over 20 min. The reaction was slowly warmed to 0° C. and then stirred for an hour at 0° C. The reaction warmed to room temperature and then stirred for 10 h. Acetic anhydride (10 mL) was added to the reaction mixture at 0° C. After several minutes methanol (10 mL) was added to the reaction. The mixture was allowed to stir for 10 min, and then concentrated to a volume of 25 mL. The reaction mixture was washed with water (100 mL) and the aqueous layer was extracted with ethyl acetate (150 mL). The combined organic layers were washed successively with aqueous sodium bicarbonate (2×100 mL) and brine (2×100 mL), dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure at less than 40° C. The resulting residue was purified by flash column chromatography on silica gel, eluting with 85:15 hexanes:ethyl acetate to provide (R)-tert-butyl 2-methyl-4-oxohex-5-en-3-ylcarbamate (2.52 g) as a white solid. 1H NMR (CDCl3): 6.50-6.32 (m, 2H), 5.85 (d, 1H), 5.22 (d, 1H), 4.56 (dd, 1H), 2.18 (m, 1H), 1.44 (s, 9H), 1.01 (d, 3H), 0.80 ppm (d, 3H).

Provenance & Evidence