GB971750A - 18:20-oxido-steroids and the preparation thereof - Google Patents

Abstract

The invention comprises an 18, 20-oxido-pregnane compound having an etherified hydroxy group in the 20-position which is derived from a lower aliphatic or alicyclic alcohol containing up to 7 carbon atoms, and a process for the preparation of a 21-unsubstituted 18, 20-oxido-pregnane compound which contains in the 20-position a double bond or a free or etherified hydroxy group (in the case of the 20-hydroxy-pregnane compound the product may exist as a 18-hydroxy-20-oxa-pregnane compound) by irradiating a 20-oxo-pregnane compound which contains in the 21-position an etherified or esterified hydroxy group (as defined above) or a halogen atom either in an inert organic solvent whereby the D 20-compound is formed or in a lower aliphatic or alicyclic alcohol containing up to 7 carbon atoms whereby the 20-ether compound is formed and, if desired, hydrolyzing a resulting 20-ether compound with a mild hydrolyzing agent to form a free 18, 20-oxido-20-hydroxy compound, and if desired, esterifying a 18, 20-oxido-hydroxy-compound (including the 18,20-oxido-20-hydroxy compound), for example with a carboxylic, sulphonic, sulphuric, phosphoric or hydrohalic acid. In the above process, the 20-oxo-pregnane reactant may be of the 5a -or 5b -series and may be saturated or unsaturated, may contain at the 21-position a formyloxy, acetoxy, propionyloxy, butyryloxy, methanesulphonyloxy or para-toluenesulphonyloxy group or a methoxy, ethoxy or tetrahydropyranyloxy group, or a fluorine, iodine, chlorine or bromine atom, and may contain free or functionally converted hydroxy or oxo groups, alkyl groups and halogen atoms as substituents-particularly 3a -, 3b -, 11a -, or 11b -hydroxy groups which may be in the form of an ester group or a D 4-3-oxo grouping-particularly in the form of a D 5-3-ethylenedioxy ketal grouping. The preferred 18,20-oxido compounds having a 20-ether group are either of the 5a - or 5b -pregnane series and containing in the 3-position or in each of the 3- and 11-positions a free or esterified a - or b -hydroxy group or of the D 5-pregnane series and containing a ketalized 3-oxo group or a free or esterified 3b -hydroxy group, for example, of the general formulae <FORM:0971750/C1/1> <FORM:0971750/C1/2> wherein R1 represents a hydroxy group etherified with a lower aliphatic or alicyclic alcohol as defined above, R2 and R3 each represent a hydrogen atom or an esterified hydroxy group, R4 represents a hydrogen atom in the a - or b -configuration and X represents two lower alkoxy groups or one lower alkylenedioxy group. Detailed examples are given describing the above processes in which D 5-18:20-cyclo-3:3-ethylenedioxy-20-hydroxy-21-acetoxy -pregnene and the corresponding 11b -acetoxy-pregnene are formed as by-products as the result of irradiating D 5-3:3-ethylenedioxy-20-oxo-21-acetoxy-pregnene and the corresponding 11b -acetoxy compound respectively. Specifications 808,173, 927,327 and 957,432 are referred to.