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Summary. Irradiation of a pentane solution of (E)-dehydro-8-ionone-epoxide (1) with light from a medium pressure mercury lamp using acetone as filter led to formation of the isomers 2, 3, 4 and 5 by novel photochemical processes.Irradiation of a 0.04 m pentane solution of (E)-dehydro-8-ionone-epoxide (1) [2] using medium pressure mercury lamp and acetone as filter led t o a mixture of products consisting mainly of the isorners 2, 3, 4 and 5 shown in Scheme 1 2 ) . The structures assigned were inferred from spectroscopic data and confirmed by degradation 3). Irradiation of 1 in pentane with a low pressure lamp in quartz apparatus (1 = 254 nm) until 50% conversion gave 2 as the only major product. Subsequent irradiation did not increase the yield of 2 but led to a more complex reaction mixture. Isomers 2-5 gave correct analyses for C1,H,,O, and mass spectra in accord with the proposed structures,

Summary. Lead tetraacctate (LTA) oxidation of the allylic alcohols 1, 10, 14 and 19 leads to the formation of thc epoxides 2, 11, 15 and 20, products of a novel internal addition reaction of the elcctron deficient alcohol oxygen to thc allylic double bond. I n some cases (10, 14) the forma- zum Strukturnachweis uberfiihrte man 6 in den Allylalkohol 7 und erliielt bei dessen Oxydation das bekannte Keton 8 1151. Die Acetate 5 und 6 fielen zudem bei der Oxydation des d3-ungesattigten Alkohols a-Cyclogeraniol (9) [16] an: Nach 14 Stunden betrug der Eduktumsatz SO%, als einzige Oxydationsprodukte isolierte man 5