Monoacetals Derived From 12-α-Hydroxyandrosta-1,4-diene-3,17-dione and Androsta-1,4-diene-3,12,17-trione

Abstract

Conversion of 12α-hydroxyandrosta-1,4-diene-3,17-dione (5) into the corresponding 17-cyclic ethylene acetal (1) was accompanied by acid- catalysed attack of ethylene glycol at C3 to give 17,17-ethylenedioxy- 3-(2′-hydroxyethoxy)-1-methylestra-1,3,5(10)-trien-12a-ol (2), which was the major product with prolonged reaction times. Exchange dioxolanation of androsta-1,4-diene-3,12,17-trione (8), prepared by Jones oxidation of (5), gave selectively the 12-monoacetal (9): the regioisomeric 17-monoacetal (4) was obtained by oxidation of the hydroxy acetal (1) with chromium trioxide in pyridine. The trione (8) likewise afforded selectively the 12,12-ethylenedithio acetal (11).

Treatment of the trione (8) with p- toluenesulfonic acid in refluxing benzene gave 1-hydroxy-4-methylestra-1,3,5(10)-triene-12,17- dione (7a).