화학공학소재연구정보센터
Journal of Hazardous Materials, Vol.375, 26-32, 2019
C-14-Labelling of the natural steroid estrogens 17 alpha-estradiol, 17 beta-estradiol, and estrone
The worldwide environmental occurrence of natural steroid estrogens has drawn increasing concerns. However, the fate of the estrogens, especially the a-isomer of estradiol, in the environmental matrices is still obscure. Using C-14-radioactively labelled forms of these estrogens can facilitate and is sometimes a prerequisite for studying their transformation and residual distribution in the environment, but the availability of labelled compounds (owing to commercially high prices or unavailable) hampers such studies. Here we developed simple and stable methods to synthesize C-14-labelled estradiol isomers and estrone using relatively low-priced [carboxyl.C-14]-labelled sodium acetate as a precursor. The radiochemical syntheses started from an enol lactone, which was prepared from nandrolone by oxidation to open the A-ring followed by recyclization. Inversion of the 17 beta-hydroxyl group into its 17 alpha-form was achieved via the Walden inversion using the Mitsunobu reaction. [3-C-14]17 beta-estradiol, [3-C-14]-17 alpha-estradiol, and [3-C-14]-estrone were synthesized in five, six, and seven steps with an overall radiochemical yield of 17.4%, 16.2%, and 13.9%, respectively. The synthesized C-14-labelled compounds provide materials for studying the fate and behavior of estrogens in complex environmental matrixes and for further synthesis of their C-14-labelled sulfate and glucuronide conjugates.