(S)-(+)-1,5-DIMETHYL-4-PHENYL-1,5-DIHYDRO-2H-PYRROL-2-ONE AND (R)-(-)-1,5-DIMETHYL-4-PHENYL-1,5-DIHYDRO-2H-PYRROL-2-ONE BY CARBENE RING CONTRACTION AND DECARBOXYLATION OF (2R,3S)(-)-6-DIAZO-3,4-DIMETHYL-2-PHENYLOXAZEPANE-5,7-DIONE AND (2S,3R)-(+)-6-DIAZO-3,4-DIMETHYL-2-PHENYLOXAZEPANE-5,7-DIONE

Catalytic decomposition of diazo compound 1, which is readily available in homochiral form, leads exclusively to the unsaturated, enantiomerically pure lactam 2. This chiral C5‐building block and its enantiomer open access to asymmetric pyrrolidinones and pyrrolidines, which are of potential therapeutic utility. (Figure Presented.) Copyright © 1995 by VCH Verlagsgesellschaft mbH, Germany