Nonstabilized <i>N</i>-Unsubstituted Azomethine Ylides:  A Synthesis of Indolizidine 239CD

Abstract

[formula: see text] Treatment of a (2-azaallyl)stannane with HF.pyridine generated a nonstabilized N-unsubstituted azomethine ylide, which was found to undergo an efficient and stereoselective dipolar cycloaddition with phenyl vinyl sulfone to produce a trans-2,5-dialkylpyrrolidine that was further transformed into the dendrobatid alkaloid indolizidine 239CD.