New Synthesis of 3-Alkyl Coumarins

Abstract

3-Alkyl coumarins are reported to have anthelmintic, hypnotic and insecticidal properties^1–3. Here we report a novel general method for the synthesis of 3-alkylated coumarins. This involves direct C-alkylatioa at the C-3 position of 3-carbethoxy-3,4-dihydrocoumarin followed by hydrolysis, decarboxylation and dehydrogenation of the resulting dihydrocoumarin. 3-Methyl-, 3-ethyl-, 3-n-pro-pyl-, and 3-benzylcoumarins have been synthesised in good yields following the same procedure depicted in the Scheme-1.