Synthesis, Structure, and Reactivity of Secosteroids Containing a Medium-Size Ring. Part 35. Photooxidations of some (Z)- and (E)-1(10)-unsaturated 5,10-secosteroids in acetone solution

UV Irradiation of (Z)‐ and (E)‐1(10)‐unsaturated 5,10‐secosteroids 1–4 in acetone solution effected, besides (Z/E)‐isomerization, (i) a stereospecific epoxidation (only in the presence of O2), which, depending on the configuration ((Z) or (E)) in the starting steroid, gave cis‐epoxides 5 and 8 (from the (Z)‐compounds 1 and 3) or trans‐epoxides 6,9, and 10 (from the (E)‐compounds 2 and 4), and (ii) oxidative acetone addition to the olefinic double bond producing 1‐acetonyl derivatives 7 and 11a, b.