Iodine → tert-Butyl 5-(tert-butyldiphenylsilanyloxy)-3-[4-iodo-5-(3-isobutylcyclobutyl)isoxazol-3-yl]valerate

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Reaction Steps

tert-Butyl 3-[2-(tert-butyldiphenylsilanyloxy)ethyl]-6-(3-isobutylcyclobutyl)-4-methoxyimino-5-hexynoate (53.6 g) and acetonitrile (320 mL) were mixed. To the mixture was added iodine (49.6 g) at ice temperature and the reaction mixture was stirred for 3 hr. After pouring the mixture into the solution of aqueous 20 w/v % sodium thiosulfate (380 mL) at ice temperature, the mixture was extracted with chloroform (1 L) and dried over magnesium sulfate. The magnesium sulfate was filtered off and the filtrate was concentrated in vacuo. After an addition of silica gel (80 g) and ethyl acetate/hexane=1/20 (600 mL) to the residue, the mixture was stirred at RT for 1 hr. The silica gel was filtered off and the filtrate was concentrated in vacuo. The residue was purified twice by silica gel column chromatography (Eluent: ethyl acetate/hexane=1/60→1/50→1/45) to give the title compound (38.2 g).

Provenance & Evidence