GB990485A - Production of steroidal cyclic acetals - Google Patents

Abstract

The invention comprises compounds having the formulae <FORM:0990485/C2/1> wherein A represents a -hydroxymethylene, b -hydroxymethylene, a -alkanoyloxymethylene in which the alkyl moiety has 1-5 carbon atoms, carbonyl or alkylenedioxymethylene in which the alkylene moiety has two or three carbon atoms, R represents alkanoyl in which the alkyl moiety has 1-5 carbon atoms or alkoxythiocarbonyl in which the alkyl moiety has 1-5 carbon atoms and the double bond can be present between the 5-position and its adjacent position except 10-position, R1 represents hydrogen, alkyl having 1-5 carbon atoms, phenyl, alkylphenyl in which the alkyl moiety has 1-5 carbon atoms, R11 represents alkyl having 1-5 carbon atoms, phenyl, alkylphenyl in which the alkyl moiety has 1-5 carbon atoms or phenylalkyl in which the alkyl moiety has 1-5 carbon atoms, when linked together R1 and R11 represent cyclic alkyl having five or six carbon atoms and a process for preparing a steroidal cyclic acetal which comprises reacting a 16-halogeno-17-oxo steroid with a reactive thioalkanoic acid derivative, reducing the resulting 16b -substituted thio-17-oxo steroid with an alkali metal hydride compound and condensing the resultant 16b -mercapto-17b -hydroxy steroid with a carbonyl compound in the presence of an acidic catalyst to obtain a 16b -mercapto-17b -hydroxy steroid 16, 17-cyclic acetal. As reactive thioalkanoic acid derivative there may be used an alkali metal salt of thioalkanoic acid or an alkali metal salt of alkyldithiocarbonic acid. The reduction step may be effected with lithium aluminium hydride, lithium borohydride or sodium borohydride and the third step is effected by means of a carbonyl compound having the formula R1-CO-R11 wherein R1 and R11 are as defined above.