Photochemische Reaktionen 4. Mitteilung. Beeinflussung der photochemischen Isomerisierung gekreuzter Dienone durch Substituenten am Chromophor

Irradiation of 1‐dehydro‐4‐methyl‐testosterone (IV) in dioxane solution affords as a single product an isomer, which on the basis of extensive degradation is shown to possess structure V. A similar photochemical transformation leads from 1‐dehydro‐2,4‐dimethyl‐testosterone (XXXVII) to the corresponding lumiproduct XXXVIII. Since it has been previously shown that 1‐dehydro‐testosterone (III) under the same conditions yields a mixture of 8 compounds, it appears now that the photochemical isomerisation of cross‐conjugated steroidal dienones is profoundly affected by the presence of a methyl substituent at C‐4.