| abstract |
A process for preparing compounds of formula: (II) by esterification of the C-17 hydroxyl group of 6.alpha., 9.alpha.-difluoro-11.beta., 17.alpha.-dihydroxy-16.alpha.-methyl-3-oxoandrosta-1,4-diene-17.beta.-carbothioic acid, the compound of formula: (I) comprises treating compound (I) with a slight excess of an acyl chloride of general formula R-COCI, where R represents -CH2CH3, -CH2CH2CH3 or -CH(CH3)2, in an inert solvent, in the presence of a tertiary amine. Preferably the process is carried out using pyridine in the presence of acetone at a temperature of from 5 ~C to -20 ~C. z. |