Oxidative transformations of 4‐methylcoumarins using dimethyldioxirane

Efficient regioselective oxidation of the double CAC bond of 4-methylcoumarins with isolated dimethyldioxirane was performed, and related hydroxy and epoxy derivatives were obtained in good yields. All of obtained epoxides and most of hydroxy derivatives are novel compounds. The position of different electron-donating groups attached at the aromatic part of molecule shows significant influence on kinetics and course of the reaction.