A convenient one-pot synthesis of 4-methyl-3-phenyl-, 3-aryl- and 3-aryl-4-phenylcoumarins

Abstract

Thermal condensation of 2'-hydroxyacetophenones 1a-e with phenylacetic acid 2a in refluxing diphenyl ether gives 4-methyl-3-phenylcoumarins 3a-e. Similarly, reaction of 2-hydroxybenzaldehydes 1f-m and 2-hydroxybenzophenones 1n-p with phenylacetic acids 2a-d gives the corresponding 3-arylcoumarins 3f-m and 3-aryl-4-phenylcoumarins 3n-p respectively. Formation of esters 4 and 5 and benzofuran 6 is also observed.