ASYMMETRIC FORMAL TOTAL SYNTHESIS OF (-)-SWAINSONINE

A new concise noncarbohydrate-based enantioselective approach to (-)-s wainsonine 1 is described, utilizing the kinetic resolution of alpha-f urfuryl amide 4 and the Sharpless AD reaction of 9a as key steps. Kine tic resolution of alpha-furfuryl amide 4 using the modified Sharpless asymmetric epoxidation reagent with D-(-)-DIPT as the chiral ligand, g ave the chiral building block the dihydropyridone 5. Reduction of the alpha,beta-unsaturated ketone 6a with sodium boranuide gave the 3 beta -OH product 7. Dihydroxylation of 9a, with Sharpless AD reagent using DHQ-CLB as the chiral ligand, provided the 1,2-glycols 10a and 10b in ratio of 10:1. Detosylation of the triol 11 afforded the amino alcohol , which underwent intramolecular cyclization by treatment with CCl4-PP h(3)-Et(3)N giving (-)-8-benzyloxy-swainsonine 12. Compound 12 was con verted into the acetonide 13, which underwent subsequent formal deprot ections to afford (-)-swainsonine 1.