Process for preparing 21 acyloxy-.DELTA.4,9(11),16 pregnatrienes 3-20-dione

A process for the preparation of a compound of the formula ##STR27## wherein R.sub.1 is acyl of 1 to 8 carbon atoms comprising reacting a compound of the formula ##STR28## wherein Hal is chlorine or bromine, R is selected from the group consisting of alkyl of 1 to 6 carbon atoms, aralkyl of 7 to 15 carbon atoms and a silylated group, K is a protective group selected from the group consisting of ##STR29## n is 2 or 3 and the wavy lines mean the groups may have either isomer form or are mixtures thereof with a reducing agent to obtain a compound of the formula ##STR30## in which K and Hal are defined as above, reacting the latter with an oxidizing agent to obtain a compound of the formula ##STR31## which is subjected to the action of an acyloxylation agent to obtain a compound of the formula ##STR32## the protected 3-oxo function of which is deprotected to obtain the compound of formula A.