Hydrochloric Acid → (2S,4S)-4-triphenylmethylthio-2-methoxycarbonyl-1-p-nitrobenzyloxycarbonylpyrrolidine

Participants

Reaction Steps

To a suspension of sodium hydride (1.26 g) (60% dispersion in oil) in dimethylformamide (50 ml) under ice cooling is added triphenylmethylmercaptan (10.9 g) in small portions and stirred for 5 minutes at room temperature. A solution of crude (2S,4R)-4-methanesulfonyloxy-2-methoxycarbonyl-1-p-nitrobenzyloxycarbonylpyrrolidine (2:10.6 g) in dimethylformamide (80 ml) is added to this mixture, and the whole mixture is stirred in an oil bath at 50° C. overnight. The reaction mixture is diluted with ethyl acetate and mixed with ice water containing 1N-hydrochloric acid (35 ml). The organic layer is taken, washed with water and satd. brine, dried over sodium sulfate, and concentrated in vacuo. The residue is purified by silica gel chromatography (toluene-ethyl acetate) to give (2S ,4S)-4-triphenylmethylthio-2-methoxycarbonyl-1-p-nitrobenzyloxycarbonylpyrrolidine (3:9.12 g) an orange foam (Yield: 52% from hydroxyproline) and the starting compound (2:3.11 g: Yield: 29%).

Provenance & Evidence