Novel Synthesis of the Pyrrolizidine Skeleton by Sulfenocycloamination. Total Synthesis of (+/-)-Retronecine and (+/-)-Turneforcidine

Article abstract of DOI:10.1021/jo00169a005

The ω-unsaturated amines 1, 6, and 7 were converted into pyrrolidines 4 and 8 and piperidine 9, respectively, by treatment of their hydrochlorides with benzenesulfenyl chloride followed by base-induced ring closure.This novel sulfenocycloamination ring closure was applied to the synthesis of the pyrrolizidine ring (e.g., 20) and to the total synthesis of (+/-)-retronecine (32) and (+/-)-turneforcidine (34).