Radical cyclization of chiral N-(1-cycloalken-1-yl)-α-haloacetamides: Synthesis of optically active bicyclic pyrrolidinones

Article abstract of DOI:10.1016/0957-4166(96)00326-6

Asymmetric induction in the 5-endo-trig radical cyclization of N-(1-cycloalken-1-yl)-α-haloacetamides has been examined. α-Iodo amide 7 bearing an (S)-1-(1-naphthyl)ethyl group on the nitrogen afforded a 92:8 mixture of bicyclic lactams 9a,b, which was transformed into 3aR,7aR)-octahydroindol-2-one 10a in 77% ee. α-Bromo amide 11 bearing an N-(R)-1-phenethyl group provided a 61:39 mixture of 13a,b. The major product 13a was then transformed into enantiomerically pure (1S,5S)-2-azabicyclo[3.3.0]octan-3-one 15.