non-6-en-2-one (1) and its 9-oxa analog have been found to rearrange principally to methyl 5,6-dihydro-2//-pyran-2-propionate derivatives upon irradiation in methanol. When the irradiation of the thia system was carried out in deuteriomethanol, the product formed was found to have incorporated the deuterium atom in the thiapyran portion of the molecule. Irradiation of the oxa analog in deuteriomethanol, however, gave ester which had the deuterium atom located adjacent to the carbonyl group. This result indicates that the thia system is significantly different from its oxa analog in its photobehavior and that carbonyl-sulfur interactions in the excited state play an important role in the photochemistry of cyclic ß-keto sulfides. Wavelength and solvent effects were also observed in the photochemistry of 1. Possible mechanistic pathways to the observed photoproducts are discussed. 8 H) in the nmr.The mass spectrum of 3a shows the Mechanism A

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Aus trans‐Benzoyl‐phenyl‐aziridin (I) entstehen mit tert.‐Butylhypochlorit die beiden isomeren N‐Chlor‐Verbindungen (II) und (III), die mit Natriumboranat wieder zu (I) reduziert werden und beim Belichten zum Oxazol (IV) cyclisieren.