Intermolecular [2 + 2] Cycloaddition of Oxime Ethers with Indole Derivatives via Visible Light Energy Transfer Catalysis

The [2 + 2] cycloaddition of indole is a method for constructing polycyclic compounds containing an indoline scaffold. An intermolecular [2 + 2] cycloaddition reaction between indole derivatives and oxime ethers using visible-light-mediated energy transfer catalysis has been developed. This reaction can be used to synthesize fused or bridged ring compounds containing both indole and azetidine structural units.