GB775565A - Process for the preparation of new esters of the steroid series - Google Patents

Abstract

The invention comprises: (a) 11-formoxy steroids, with the exception of 11a -formoxy steroids of the pregnane series and the formic acid esters of 11a -hydroxytestosterone, 11a -hydroxy - 10 - normethyltestosterone, 11a -hydroxy - 17a - methyltestosterone, 11a -hydroxy - 10 - normethyl - 17a - methyltestosterone and 11a :22-dihydroxy-3-ketobisnor-4-cholene; (b) the preparation thereof by esterifying the corresponding 11-hydroxy compounds with formic acid, e.g. by the use of a mixture of formic acid and acetic anhydride; and (c) the application of (b) to the protection of an 11-hydroxy group during a steroid synthesis, the 11-formoxy group being thereafter hydrolysed, and subsequently, if necessary, any further reaction step performed. The starting materials may be saturated or unsaturated (e.g. in the 1-, 4-, 5-, 14- or 16-positions), and may contain further substituents (particularly free hydroxy, oxo or carboxyl groups or their derivatives, or halogens, e.g. in the 2-, 3-, 4-, 5-, 6-, 7-, 9-, 12-, 14-, 15-, 17-, 20- or 21-positions). In examples: (1) D 4 - 3 - keto - 11a - hydroxyetiocholenic acid is esterified with formic acid in the presence of acetic anhydride and pyridine; (2) 3b -acetoxy-11b -hydroxyalloetiocholanic acid is esterified with formic acid and acetic anhydride, the resulting 11b -formoxy compound is treated with diazomethane in ether, the diazoketone obtained is treated with methanolic caustic potash to produce 3b : 11b -dihydroxy-20-keto21-diazoallopregnane, and this is heated with glacial acetic acid to form 3b : 11b -dihydroxy20-ketopregnane 21-monoacetate which is further acetylated with acetic anhydride and pyridine to give 3b : 21-diacetoxy-11b -hydroxy-20-ketoallopregnane.