Photo-induced difluoroalkylation/cyclization of alkyne ketones: a novel strategy to access difluoroalkyl thiofavones.

A photo-induced electron donor-acceptor (EDA) complex enabled tandem reaction of alkyne ketones via a radical difluoroalkylation/cyclization cascade sequence is reported. The EDA complex plays a key role, and the C-Br bond homolysis process may also be involved for this transformation. Varieties of difluoroalkyl-substituted thiofavones can be smoothly assembled in moderate to good yields under photocatalyst-, metal- and oxidant-free conditions, thus offering potential applications for pharmaceutical research.