Synthesis of Indolizines and Benzoindolizines by Annulation of Donor‐Acceptor Cyclopropanes with Electron‐Deficient Pyridines and Quinolines

Abstract

Abstract The formal [3+2] dipolar cycloaddition (or annulation) of donor‐acceptor cyclopropanoate esters with pyridines and 5‐nitroquinoline is reported. Electron‐deficient pyridine dipolarophiles (R=CN, CO 2 Et, COMe) participate in the annulation whereas electron rich species do not. The product 2,3‐dihydroindolizines undergo rapid autooxidation, and the X‐ray structures for two of the aromatic products are reported.