A process for prepg. esters, such as I (R = CO(CH2)n, COCHMe2, n = 1, 2), was disclosed and comprised esterification of the C-17 hydroxyl group of 6?,9?-difluoro-11?,17?-dihydroxy-16?-methyl-3-oxoandrosta-1,4-diene-17?-carbothioic acid I (R = H) with a slight excess of a corresponding acyl chloride, RCOCl, inert solvent the presence of a tertiary amine.