FACILE PREPARATION OF 3,4-BENZOCOUMARINS FROM 2-ARYLBENZOIC ACIDS WITH NCS AND NaI

Treatment of 2-arylbenzoic acids with N-chlorosuccinimide (NCS) and NaI at 70 degrees C under fluorescent lighting condition gave the corresponding 3,4-benzocoumarins in good yields under transition-metal-free condition. It was found that the reactivity of NCS with NaI for the formation of 3,4-benzocoumarins from 2-arylbenzoic acids was as high as that with NIS. Thus, the formation of carboxyl radicals and their cyclization onto an aromatic ring from 2-arylbenzoic acids with much less expensive NCS and NaI, than NIS could be successfully carried out to form 3,4-benzocoumarins.