Regioselective synthesis of bromo-substituted 3-arylcoumarins

Regioselective syntheses of 3-arylcoumarins possessing a bromine substituent either on the 3-aryl ring, the coumarin moiety or on a lateral chain of a coumarin is reported. The regioselectivity is influenced by the substituents present in the substrates. Two different bromination methods are described and compared. Perkin condensation of 5-methylsalicylaldehyde and phenylacetic acid or para-methoxyphenylacetic acid affords the desired coumarins. Three different bromine substitution patterns are accessed starting from 5-methylsalicylaldehyde.