作者:Nieves P. Ramirez、Irene Bosque、Jose C. Gonzalez-Gomez
DOI:10.1021/acs.orglett.5b02269
日期:2015.9.18
A metal-free dehydrogenative lactonization of 2-arylbenzoic acids at room temperature was developed. This work illustrates the first application of visible-light photoredox catalysis in the preparation of benzo-3,4-coumarins, an important structural motif in bioactive molecules. The combination of photocatalyst [Acr(+)-Mes] with (NH4)(2)S2O8 as a terminal oxidant provides an economical and environmentally benign entry to different substituted benzocoumarins. Preliminary mechanistic studies suggest that this reaction most likely occurs through a homolytic aromatic substitution pathway.