Acridinium amidate as a hydrogen-bonding photocatalyst for direct decarboxylative alkylation of native carboxylic acids

Abstract

The direct generation of carbon radicals from carboxylic acids under visible-light photocatalysis offers an appealing strategy for molecular diversification. Here, we report a decarboxylative Giese-type addition using a zwitterionic acridinium amidate as a uniquely effective photocatalyst, which enables the efficient and selective activation and functionalization of a broad range of carboxylic acids without an external base or oxidant. The catalytic process relies on the formation of a hydrogen-bonded complex between the carboxylic acid and amidate, which triggers proton-coupled electron transfer upon photoexcitation to generate the corresponding carboxyl radical. This method featuring neutral conditions demonstrates excellent functional group tolerance and is applicable to structurally demanding substrates, including complex natural products and pharmaceutically relevant compounds.