Generation of 4-substituted coumarins via C–H bond activation under palladium bromide–copper(I) bromide cooperative catalysis

A palladium bromide and copper(I) bromide co-catalyzed reaction of 4-tosyloxy coumarin with benzo[d]oxazole/oxazole/benzo[d]thiazole via C–H activation is described, which generates 4-substituted coumarins in moderate to good yields. 4-Tosyloxy quinolin-2(1H)-one and 2H-pyran-2-one could be applied in this transformation as well.