A small molecule EnT photocatalyst for rapid [2+2] cycloaddition

Identifying novel catalysts for light-induced energy transfer (EnT) processes is crucial for advancing EnT-based chemical reactions. This work demonstrates that the readily available acylsilane, 1-(tert-butyldimethylsilyl)ethan-1-one, serves as an effective catalyst for both intra- and intermolecular [2 + 2] cyclization of dienes. This catalyst features a low molecular weight (Mw = 158.32 g/mol), and the cyclization reactions can be completed within 30 min. Detailed mechanistic studies support an EnT process, and the high Stern-Volmer quenching constant (K SV = 55.539 mM −1 ) rationalizes the short reaction time. A small molecule acylsilane worked as an effective catalyst for dienes' intra- and intermolecular [2 + 2] cycloaddition. The cycloaddition can be completed within 30 min.