GB777689A - Cyclopentanopolyhydrophenanthrene compounds and their preparation - Google Patents

Abstract

The invention comprises compounds having the formula: <FORM:0777689/IV(b)/1> in which the 3-position is occupied either by a bivalent group convertible to keto by acid hydrolysis, e.g. a cyclic ketal, or by a pair of univalent groups together convertible to a single keto group by acid hydrolysis, e.g. a non-cyclic ketal, and compounds having the formula: <FORM:0777689/IV(b)/2> in which the 3-position is occupied by a univalent group which is convertible to keto by acid hydrolysis, e.g. an enol ether, the corresponding 7-keto compounds and the preparation thereof by reacting a 1 - carboalkoxymethyl-2 - acetonyl - 2,4b - dimethyl - 4 - keto - 7 - substituted - 1,2,3,4,4a,4b,5,6,7,8,10,10a - dodecahydrophenanthrene under anhydrous conditions with a strongly basic substance, e.g. sodium, sodium hydride, sodamide, sodium methoxide and potassium t-butoxide. The 3-blocked compound may be hydrolysed to the corresponding 3-keto compound with acid, e.g. p-toluene sulphonic acid. An example describes the production of stereoisomers of D 5 - 3 - ethylendioxy-11,16,20 - triketo - pregnene and of D 4 - 3,11, 16,20 - tetraketo - pregnene. Specifications 763,208, 777,688 and 777,690 also are referred to.