Obtainment of 17 beta-estradiol or 17 beta-estradiol-17 alpha-deuterium through stereoselective reduction of estrone, using NaBH4 and LiBD4 respectively in the presence of a crown ether

The present paper investigates the reduction of estrone 1 to estradiol 2, i u methylene chloride in the presence of a crown ether (CE), with solid NaBH 4 or LiBD4 in a solid/liquid diphase system. CEs involved in the study were 18-crown-6 (18C6), 15-crown-5 (15C5) and 12-crown-4 (12C4). Our results sh ow that in the case of the reduction process using NaBH4, the 18C6 macrocyc lic ligand was the most efficient. The process is stereoselective leading t o 17 beta -estradiol) being also applied in labelling through deuteration, yielding to 17 beta -estradiol-17 alpha -deuterium (starting from estrone 1 , in the presence of LiBD4 and crown ether 12C4).