1H-Imidazole-4-carbaldehyde → (2R,4R)-1-allyloxycarbonyl-4-t-butyldimethylsilyloxy-2-{2-(5-formylimidazol-1-yl)ethyl}pyrrolidine

Participants

Reaction Conditions

Reaction Steps

To a solution of (2R,4R)-1-allyloxycarbonyl-4-tert-butyldimethylsilyloxy-2-(2-methanesulfonyloxyethyl)pyrrolidine (63 g) and 4-formylimidazole (17.8 g) in N,N-dimethylformamide (300 ml) was added potassium tert-butoxide (20.8 g) by portions. Then, the mixture was stirred at 45° C. for 2 hours. Evaporation of the solvent gave a residue, which was dissolved in a mixture of ethyl acetate (1.5 l) and water (200 ml). The organic layer was separated, washed in turn with 1N hydrochloric acid (100 ml) and brine (300 ml×3), and dried over magnesium sulfate. Evaporation of the solvent gave an oil, which was chromatographed on silica gel (2 l) eluting with a mixture of hexane and ethyl acetate (1:1 to 1:2 to 0:1). The former active fractions were collected and concentrated in vacuo to give (2R,4R)-1-allyloxycarbonyl-4-tert-butyldimethylsilyloxy-2-{2-(5-formylimidazol-1-yl)ethyl}pyrrolidine (14.9 g).

Provenance & Evidence