Photocatalytic Decarboxylative [2 + 2 + m] Cyclization of 1,7-Enynes Mediated by Tricyclohexylphosphine and Potassium Iodide.

A novel photocatalytic decarboxylative [2 + 2 + m] cyclization of 1,7-enynes with alkyl N-hydroxyphthalimide (NHP) esters, using tricyclohexylphosphine and potassium iodide as redox catalysts, is reported for the construction of functional polycyclic compounds. This protocol tolerates primary, secondary, and tertiary alkyl NHP esters through a single reaction via decarbonylation, radical addition, C-H functionalization, and cyclization under mild conditions.