Absolute configuration of tylophorine

Abstract

The configuration at C-13a in tylophorine (I) has been established as S. Ozonolysis of tylophorine gave (S)-pyrrolidine-2-acetic acid identical with a sample synthesized from (S)-proline. The absolute configuration of analogous alkaloids of the group can be deduced by comparison of their o.r.d. spectra with that of tylophorine.