Divergent total syntheses of (-)-aspidospermine and (+)-spegazzinine.

ABSTRACT: Divergent total syntheses of (+)-spegazzinine (1) and (-)-aspidospermine (2) and their extensions to the synthesis of C19-epi-aspidospermine and C3-epi-spegazzinine are detailed, confirming the relative stereochemistry and establishing the absolute configuration of (+)-spegazzinine. A powerful intramolecular [4 + 2]/[3 + 2] cycloaddition cascade of a 1,3,4-oxadiazole provided the pentacyclic skeleton and all the requisite stereochemistry of the natural products in a single reaction that forms three rings, four C-C bonds, and five stereocenters.

SUBMITTER: Lajiness JP 

PROVIDER: S-EPMC3337885 | biostudies-literature | 2012 Apr

REPOSITORIES: biostudies-literature