Regioselective transition metal-free acylation of coumarins via cross-dehydrogenative coupling reaction of coumarins and aldehydes

Abstract A transition metal-free cross-dehydrogenative coupling reaction is described for the preparation of 3-acylcoumarins. Heating a mixture of a coumarin, an aldehyde, and the K 2 S 2 O 8 /Aliquat 336 system in chlorobenzene at 100 °C for 8 h regioselectively afforded the corresponding 3-acylcoumarin derivatives in good to excellent yields.