Photochemical Reactions. 145th Communication. Carbonyl vs. Epoxyketone Photochemistry: Photolysis of 1,2;3,4-Diepoxy-2,6,6-trimethyl-1-cyclohexyl Methyl Ketone

Article abstract of DOI:10.1002/hlca.19850680517

The synthesis and photolysis of the title compound 3 is described.Irradiation (λ > 280 nm, MeCN) of the di-epoxyketone 3 leads predominantly to γ-H abstraction.Cyclization furnishes the cyclobutanols 22-24, while cleavage gives compound 25, presumably via the allene-oxide intermediate 36.Further, products 27 and 28 are formed by Norrish fragmentation and by initial cleavage of the C(α)-O bond of the oxirane, respectively.The structures of the products 22-25, 27, and 28 were assigned on the basis of the spectral data of the photolysis products of the 13C-labelled diepoxyketone <6,6-dimethyl-13C2>-3 and by X-ray analysis of the compounds 24 and 35, the latter being the p-nitrobenzoate of 22.