Photocatalytic decarboxylative [2 + 2 + 1] annulation of 1,6-enynes with N-hydroxyphthalimide esters for the synthesis of indene-containing polycyclic compounds

Abstract

An efficient photoredox-mediated [2 + 2 + 1] cascade annulation of 1,6-enynes with N-hydroxyphthalimide esters was reported for the synthesis of a series of indene-containing polycyclic frameworks through a sequence of radical addition, 5-exo-dig cyclization, 1,n-H shift and 5-endo-trig cyclization. This protocol exhibits excellent functional group tolerance for establishing spiro and non-spiro polycyclic architectures under mild conditions. Moreover, this transformation could also be achieved smoothly via a simple phosphine/iodide-based photoredox system.