Epoxidation of Enamines by Dimethyldioxirane: Formation of 1,4‐Dioxanes by Enamine Epoxide Dimerization

The 1,4‐dioxanes 3a–f, which constitute dimers of the enamine epoxides 2a–f, were obtained in excellent yields as crystalline products during the oxygen transfer to the corresponding enamines by dimethyldioxirane (DMD) in acetone. In methanol at –78°C, enamine 1b gave with dimethyldioxirane the β‐hydroxy acetal 4b as the expected trapping product of the intermediary enamine epoxide 2b.