Cerium(III) chloride → (S)-tert-butyl (2,2,3,3,11,11,12,12-octamethyl-7-methylene-4,10-dioxa-3,11-disilatridecan-6-yl)(2-oxopent-3-en-1-yl)carbamate

Participants

Reaction Conditions

Reaction Steps

A suspension of cerium (III) chloride (47.6 g, 193.26 mmol) in THF (200 mL) 3 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) (387 mL, 193.26 mmol) was added dropwise. The mixture was stirred at −78° C. for 1.5 hours. (5)-tert-butyl (2-(methoxy(methyl)amino)-2-oxoethyl)(2,2,3,3,11,11,12,12-octamethyl-7-methylene-4,10-dioxa-3,11-disilatridecan-6-yl)carbamate (Intermediate 278, 13.55 g, 24.16 mmol) in THF (50 mL) was then added dropwise at −78° C. The reaction was stirred at −78° C. for 1 hour and then warmed to 0° C. for 30 minutes. The reaction was quenched with 10% citric acid, diluted further with water and extracted twice with ether. The organics were dried over magnesium sulfate, filtered and concentrated. Silica gel chromatography (0%-20% ethyl acetate/hexanes) afforded the title compound (10 g, 76%) as a yellow oil.

Provenance & Evidence