Asymmetric syntheses of 2-substituted and 2,5-disubstituted pyrrolidines from (3S,5R,7aR)-5-(benzotriazol-1-yl)-3-phenyl[2,1,b]oxazolopyrrolidine

Benzotriazole, 2,5-dimethoxytetrahydrofuran, and (S)-phenylglycinol in one step gave 80% of (3S, 5R,7aR)-5-(benzotriazol-1-yl)-3-phenyl-[2,1-b]oxazolopyrrolidine (6), whose crystal structure was confirmed by X-ray crystallography. Novel chiral pyrrolidine synthon 6 reacts with organosilicon (allyltrimethylsilanes and vinyloxytrimethylsilanes), organophosphorus, organozinc, and Grignard reagents to afford chiral 2-substituted and 2,5-disubstituted pyrrolidines.