Dehydro-steroid derivs. prodn. - by reacting oxo-steroids with phosphonoacetic acid esters and reacting with diisobutyl-aluminium hydride and an acyl anhydride

摘要

In a new process for the prepn. of 17(20)-dehydro steroid derivs. of formula (I), a steroid of formula (II) is condensed with a phosphonate carbanion of the formula (R2O)2P(O)-Circled negative CH-COOH (iii) and the resulting cpd. of formula (IV) is reacted with diisobutyl-aluminium hydride and lower carboxylic acid anhydrides to give a cpd. (I). In formulae (I)-(IV), R1 is lower alkyl; Ac is lower alkanoyl; St is the residue of the A-B-C rings of a steroid contg. 1-2 structurally possible double bonds and a carbonyl or protected OH gp.; Stx is the residue of the A-B-C rings of a steroid contg. 1-2 structurally possible double bonds and a protected carbonyl or protected OH gp.; and R2 and X are lower alkyl. Cpds. (I) in which the residue St carries a lower alkoxy gp. in the 3-position and a double bond in the 5(6)-position are claimed as new cpds. (I) are intermediates for pharmacologically active substances. For example, prednisolone can be obtd. by microbiological or chemical 1,2-dehydrogenation and microbiological 11-hydroxylation. The new method of introducing the side-chain in the 17-position is technically simpler than the method of DT. 1468880. (I) is obtd. in almost quantitative yield. Specific cpds. (I) include 17(20)E/Z-21-acetoxy-4,17(20)-pregnadien-3-one.