PHOTOCHEMISTRY OF ENOLIC SYSTEMS .4. IRRADIATIION OF ENOL TRICHLOROACETATES AND A DIENOL TRICHLOROACETATE

The photolysis of enol trichloroacetates 1, 3, and 2 derived from 3-pentanone, 17β-acetoxy-5α-androstan-3-one (9) and cyclohexanone was investigated. The main products isolated in t-butyl alcohol were the α-trichloromethyl ketones 4 and 10 and an α-dichloromethylene ketone 7, respectively, the latter being formed from the α-trichloromethyl ketone 6 by loss of hydrogen chloride. In addition, the steroidal enol trichloroacetate 3 yielded the dimeric enol tetrachlorosuccinate 11. However, irradiation of 3 in cyclohexane or in isopropyl alcohol did not result in α-trichloromethyl ketone nor in its decomposition product. In cyclohexane three enol esters were isolated: 11, the enol dichloroacetate 13, and enol formate 14, and in isopropyl alcohol the two former esters and a solvent addition product 15a. Photolysis of steroidal dienol trichloroacetate 16 in both t-butyl alcohol and cyclohexane gave the trichloromethyl ketone 17 which was accompanied in the latter solvent by the α-dichloromethylene ketone 18. The properties of the novel compounds are described and the relevant photochemical pathways are discussed. © 1969, American Chemical Society. All rights reserved.