Synthesis, Structure, and Reactivity of Secosteroids Containing a Medium‐Sized Ring. Part 36. Transannular photocyclization of some unsaturated 5,10‐secosteroidal ketones: A reevaluation

Abstract

(1 3.IV. 95)The structures 9 and 8 are proposed for the single isolated irradiation product of 5-oxo-5,10-secocholest-I( 10)-en-3cc -yl acetate (6) [2] and for the minor product of irradiation of 5-oxo-5,10-secocholest-l(l0)-en-3~ -yl acetate (1) [3], respectively. These compounds are formed in an alternative reaction with respect to the originally observed intramolecular Puterno-Bu'chi photoprocess (transformation of 1 to oxetane 2). The formerly postulated 'active' conformations for 1 and 6 still allow explanation of their generation.Introduction. -In the penultimate part of these series [2], we had summarized the results of the irradiation experiments on unsaturated 5,lO-secosteroidal ketones and attempted to correlate the 'active' conformations of these medium-size-ring compounds with the structures of their photoproducts.

Synthesis and radical oxidation of steroidal 1-oxo-5α-alcohols

“…The course of the reaction is rather complex (Scheme 1): [4][5][6][7] the intermediate formation of radical species 2 and 3 has been suggested to give ultimately a number of compounds like enones 4, cyclization products 5 and iodides 6. 8 This limits the applicability of the reaction in a directed synthesis of corresponding seco steroids.…”