Improved process for preparing estetrol.

Abstract

This application relates to a process for preparing high-purity estetrol benzyl ether of formula (Va) useful for producing estetrol by means of a corresponding 17-hydroxyl-protected intermediate compound of formula (III), followed by purification of the compound of formula (V) by crystallization and / or through the formation of a cyclic 15α,16α-16α derivative of formula (VI) and its subsequent hydrolysis. This application relates to a process further comprising transforming delta-15-estradiol benzyl ether of formula (II) into the compound of formula (III). This application also relates to a process further comprising a debenzylation step of the compound of formula (Va) to obtain high-purity estetrol (estra-1,3,5(10)-triene-3,15α,16α,17β-tetrol) of formula (I). This application also relates to intermediate compounds of formulas (III), (Va) and (VI) useful in the process.