Cerium(III) chloride → (S)-tert-butyl 1-(tert-butyldimethylsilyloxy)-3-cyclopropylbut-3-en-2-yl(2-oxopent-3-enyl)carbamate

Participants

Reaction Conditions

Reaction Steps

A suspension of cerium (III) chloride (27.8 g, 112.95 mmol) in THF (100 mL) at room temperature was stirred vigorously for 2 hours. The suspension was cooled to −78° C. and (E)-prop-1-enylmagnesium bromide (0.5 M in THF) (226 mL, 112.95 mmol) was added dropwise. The mixture was stirred at −78° C. for 1.5 hours. (S)-tert-butyl 1-(tert-butyldimethylsilyloxy)-3-cyclopropylbut-3-en-2-yl(2-(methoxy(methyl)amino)-2-oxoethyl)carbamate (Intermediate 235, 5 g, 11.30 mmol) in THF (20 mL) was then added dropwise at −78° C. The reaction was stirred at −78° C. for 30 minutes and then warmed to 0° C. for 15 minutes. The reaction was quenched with 10% citric acid, diluted further with water and extracted twice with ether. The organics were washed once with brine, dried over magnesium sulfate, filtered and concentrated. Silica gel chromatography (0%-20% ethyl acetate/hexanes) afforded the title compound as a light yellow oil (4.0 g, 84%).

Provenance & Evidence