Photocatalytic site-selective C–H difluoroalkylation of aromatic aldehydes†
The direct photocatalyzed para-selective CAr–H difluoroalkylation of aromatic aldehyde derivatives has been accomplished using a newly explored catalytic system. In addition, when using para-substituted benzaldehydes as substrates, ortho-selective CAr–H difluoroalkylation was also accomplished. It is worth noting that all the above site-selectivity is opposite to traditional Friedel–Crafts reactions of aromatic aldehydes. The preliminary mechanistic investigations indicate that an electrophilic difluoroalkyl radical is involved in the catalytic cycle.