Enantioselective Total Synthesis of (+)- and (-)-Pyrrolidine 197B, a New Class of Alkaloid from the Dendrobatid Poison Frog: Assignment of the Absolute Configuration

Article abstract of DOI:10.1021/jo00004a011

Enantioselective total synthesis of both enantiomers of pyrrolidine 197B (1), a new class of dendrobatid alkaloid, is described.The synthesis begins with the C₂ symmetric S,S or R,R diepoxides 4, derived from (S,S)-1,2,5,6-hexanetetraol (2) as a single common chiral synthon, and involves pyrrolidine formation via the cyclic sulfonates to afford (+)- or (-)-1, respectively.The (+) and (-) enantiomers of 1 were converted to the corresponding N-benzoyl derivatives (+)-27 and (-)-27, which were directly compared with 27 derived from natural 1 by HPLC using a Chiracel column.This comparison established the absolute stereochemistry of the natural enantiomer of pyrrolidine 197B as 2S,5S<(+)-1>.