An Organic EnT Photocatalyst 4CzMeBN and the Application in the Synthesis of cis-Fused Azetidines.

A powerful EnT photocatalyst 4CzMeBN has been developed and utilized in the synthesis of cis-fused azetidines via dearomative [2+2] cycloaddition under visible light. The photocatalyst 4CzMeBN is a donor-acceptor cyanoarene and features high triplet state energy and long lifetime of triplet state, which would be an alternative to widely used EnT photocatalyst Ir[dF(CF)ppy](dtbbpy)PF. The photochemical [2+2] cycloaddition provides a facile method to synthesize valuable dihydroisoquinolone-fused azetidines with high efficiency.