An efficient waste-free oxidative coupling via regioselective C-H bond cleavage: Rh/Cu-catalyzed reaction of benzoic acids with alkynes and acrylates under air

The direct oxidative coupling of benzoic acids with internal alkynes proceeds efficiently in the presence of a rhodium/copper catalyst system under air to afford the corresponding isocoumarin derivatives. The reaction forms no wastes except for water. Under similar conditions, the aerobic coupling with acrylates also takes place smoothly to produce 7-vinylphthalide derivatives via divinylation and subsequent cyclization.