Visible light mediated oxidative lactonization of 2-methyl-1,1′-biaryls for the synthesis of benzocoumarins

A visible light mediated oxidative lactonization of 2-methyl-1,1'-biaryls was developed, giving benzocoumarins in good yields. The reaction features multiple C-H functionalization processes with oxygen as the final oxidant. The corresponding 2-aldehdyes, alcohols and carboxylic acids of the 1,1'-biaryls also worked well for the reaction.