Synthesis of some novel 4-substituted coumarins having potential biological activity(Part II)

摘要

Coumarin 4-methyl acetates are oxidized to coumarin-4-methyl glyoxalate using SeO_2.Unlike the oxidative decarboxylation observed in the case of coumarin-4-acetic acid,here the oxidation is very selective for the active methylene group,without affecting the COOH group protected with ester function.The product thus obtained is analogous to the phenyl glyoxalic acid methyl ester i.e.,coumarin-4-methyl glyoxalate and can be a useful moiety for the various synthetic manipulations of heterocycles substituted at 4-position of the coumarin.