A concise diastereoselective approach to (+)-dexoxadrol, (−)-epi-dexoxadrol, (−)-conhydrine and (+)-lentiginosine from (−)-pipecolinic acid

A new diastereoselective pathway for the total synthesis of (+)-dexoxadrol, first asymmetric synthesis of (−)-epi-dexoxadrol and formal synthesis of conhydrine and (+)-lentiginosine is presented using commercially available (−)-pipecolinic acid. The key reactions utilized are Sharpless asymmetric dihydroxylation and Wittig reaction. The paper further describes the study of effect of protecting groups on dihydroxylation of a terminal olefin in piperidine ring system.