ES252505A1 - Esters of natural and synthetic estrogens - Google Patents

Abstract

The invention comprises esters and partial esters of estrogens with b (p-alkoxyphenyl)-propionic acids of the general formula <FORM:0926456/IV(a)/1> wherein R represents an alkyl group of 1 to 12 carbon atoms, and the preparation thereof by esterifying the estrogens with an acid chloride or acid anhydride of the b -(alkoxyphenyl)-propionic acids in the presence of a tertiary amine at a temperature between 0 DEG and 20 DEG C. Instead of the tertiary amine, an inert solvent may be used. The esters and partial esters may be derived from natural estrogens such as estrone, estradiol and estriol, or derivatives of natural estrogens such as 17-ethinylestradiol, or synthetic estrogens such as diethylstilbestrol, dienestrol, and hexestrol. In the case of estrogens having two or more hydroxyl groups, the esters may be mono-, di- or polyesters, or they may be mixed esters containing at least one ester radical derived from an acid of the above formula and an ester radical derived from a lower fatty acid such as acetic and propionic acids. Partial esters may also be prepared by partially hydrolysing the fully acylated estrogens. Estrone-3-esters prepared by the above method may be catalytically reduced to form a hydroxy group at the 17-position. Acid chlorides and acid anhydrides of the propionic acids of the above general formula are prepared by treating the free acids with excess thionyl chloride on a steam bath or with thionyl chloride in the presence of pyridine respectively.