DIMETHYLDIOXIRANE EPOXIDATION OF BETA-OXO ENOL ETHERS

The synthesis of the epoxides 2a–f by epoxidation of the β‐oxo enol ethers 2,2‐dimethyl‐3(2H)‐furanone (1a), (Z)‐2(ethoxymethylene)cyclohexanone (1b), and 3‐alkoxy‐5,5‐dimethyl‐2‐cyclohexenones 1c–f with dimethyldioxirane is reported. These labile epoxides (stable below 0°C) were isolated and characterized spectroscopically (IR, 1H, and 13C NMR). Warming up to room temperature led to decomposition to afford complex product mixtures. When the epoxidation of 3‐ethoxy‐5,5‐dimethyl‐2‐cyclohexenone (1c) was conducted above 0°C, the epoxide 2c afforded the rearrangement product 3‐ethoxy‐2‐hydroxy‐5,5‐dimethyl‐2‐cyclohexenone (3). Copyright © 1990 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim