Imidazole → (3R,5S)-1-allyloxycarbonyl-3-t-butyldimethylsilyloxy-5-[1-(5-chloroimidazo[5,1-b]thiazol-2-yl)-1-(methylthiothiocarbonyloxy)methyl]pyrrolidine

Participants

Reaction Steps

(3R,5S)-1-Allyloxycarbonyl-3-t-butyldimethylsilyloxy-5-[1-(5-chloroimidazo[5,1-b]thiazol-2-yl)-1-hydroxymethyl]pyrrolidine (a diastereomer mixture) (2.300 g) and 3.3 mg of imidazole are dissolved in 24.5 ml of anhydrous THF. Carbon disulfide (0.44 ml) and 292 mg of 60% sodium hydride are successively added to the solution in an argon atmosphere on ice bath, and the mixture is stirred in this state for 20 min. Methyl iodide (0.32 ml) is added dropwise thereto, and the mixture is stirred in this state for one hr. The reaction solution is diluted with 250 ml of ethyl acetate, washed with semi-saturated saline, and dried over anhydrous magnesium sulfate. The solvent is removed by evaporation under reduced pressure to give a crude product which is then purified by column chromatography on silica gel (hexane:ethyl acetate=3:1) to give 2.607 g of (3R,5S)-1-allyloxycarbonyl-3-t-butyldimethylsilyloxy-5-[1-(5-chloroimidazo[5,1-b]thiazol-2-yl)-1-(methylthiothiocarbonyloxy)methyl]pyrrolidine (a diastereomer mixture) as a yellow viscous material.

Provenance & Evidence