THERMAL AND PHOTOCHEMICAL REACTIONS OF BIACETYL WITH 1,1-DIETHOXYETHENE. "UMPOLUNG" OF THE REACTIVITY OF BIACETYL BY PHOTOCHEMICAL INDUCED ELECTRON TRANSFER.

Article abstract of DOI:10.1016/S0040-4039(01)80035-6

The thermal and photochemical reactions of biacetyl 1 and 1,1-diethoxyethene 2 are totally complementary: 1 and 2 exclusively form the 2,2-diethoxyoxetane 4 in polar solvents at room temperature.Contrary to the literature this thermal cycloaddition proceeds uncatalyzed. 1 and 2 react photochemically under exclusive formation of the regioisomer oxetane 3 - preferably in nonpolar solvents.The inversion ("Umpolung") of the reactivity of 1 is caused by the photoinduced electron transfer.