An efficient asymmetric synthesis of nitroolefinic lactones with chiral nitroenamines possessing bulky chiral leaving groups

Article abstract of DOI:10.1016/S0957-4166(97)00452-7

An efficient asymmetric nitroolefination of enolates 4a-c, 5 afforded multifunctional group nitroolefinic lactones 7a-e and 8a,b containing stereogenic quaternary carbon centers using bulky chiral nitroenamines 1a,b-3a,b as chiral auxiliaries. Studies on the effect of the bulkiness of leaving group showed that bulky nitroenamines la,b gave higher ees and yields than those of the less bulky 2a,b-3a,b. A possible cyclic transition model is proposed to elucidate the S selectivity.