Water → HCID 20639576, compound

Participants

Reaction Conditions

Reaction Steps

A 1.69 M n-butyllithium-hexane solution (7.2 ml) is added dropwise to a solution of 2.09 g of imidazo[5,1-b]thiazole in 40 ml of dry THF over a period of 10 min while maintaining the temperature at −70° C. or below, and the mixture is stirred at that temperature for 2 hr. A solution of 5.32 g of (3R,5S)-1-allyloxycarbonyl-3-t-butyldimethylsilyloxy-5-formylpyrrolidine in 20 ml of THF is gradually added dropwise to the mixed solution, and the mixture is stirred at −70° C. for 1.5 hr. The temperature is raised to 0° C. over a period of one hr, and the mixture is stirred at 0° C. for one hr and further at room temperature for 1.5 hr. Water is added to the reaction solution, and the mixture is extracted three times with ethyl acetate. The organic layer is washed twice with saturated saline, dried over anhydrous magnesium sulfate, and filtered, and the solvent is removed by evaporation under reduced pressure. The resultant crude product is successively purified by column chromatography on Sephadex LH-20 (dichloromethane:methanol=1:1) and on silica gel (hexane:ethyl acetate=1:1) to give 0.92 g of (3R,5S)-1-allyloxycarbonyl-3-t-butyldimethylsilyloxy-5-[1-hydroxy-1-(imidazo[5,1-b]thiazol-2-yl)methyl]pyrrolidine (a diastereomer mixture) and 1.85 g of (3R,5S)-1-allyloxycarbonyl-3-t-butyldimethylsilyloxy-5-[1-hydroxy-1-(imidazo[5,1-b]thiazol-3-yl)methyl]pyrrolidine (a diastereomer mixture) as a yellow amorphous material.

Provenance & Evidence