Catalyst‐Free [3+2] Cycloaddition of Isoquinolinium/Pyridinium Ylides and Electron‐Deficient Alkenes

Abstract

The development of simple‐to‐operate methods for the preparation of indolizidine derivatives are of great importance. A mild one‐pot protocol for the [3+2] cycloaddition of isoquinolinium/pyridinium ylides and electron‐deficient alkenes using NaBH₃CN as reductant has been developed. The protocol has a broad substrate scope (more than 40 examples) and provides various novel hexahydroindolizidine derivatives in high yields and excellent diastereoselectivities (up to >20/1).