Highly Diastereoselective Synthesis of Polycyclic Indolines through Formal [4+2] Propargylic Cycloaddition of Indoles with Ethynyl Benzoxazinanones

A formal 4+2] propargylic annulation of indoles and pyrrole with ethynyl benzoxazinanones was described. This protocol provides a concise synthesis of tetrahydro‐5H‐indolo2,3‐b]quinolines and tetrahydro‐3H‐pyrrolo3,2‐b]quinoline, the core structures of alkaloid frameworks, featuring excellent yields, high diastereoselectivity, mild conditions and wide substrate scope.