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A rapid synthesis of A‐ring bromine‐77‐labelled estrogens with high specific activity
Author(s) -
Wilbur D. S.,
Bentley G. E.,
O'Brien H. A.
Publication year - 1981
Publication title -
journal of labelled compounds and radiopharmaceuticals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.432
H-Index - 47
eISSN - 1099-1344
pISSN - 0362-4803
DOI - 10.1002/jlcr.2580181115
Subject(s) - chemistry , structural isomer , bromine , bromide , electrophile , ring (chemistry) , halogenation , high performance liquid chromatography , steroid , sodium bromide , sodium , chromatography , stereochemistry , medicinal chemistry , organic chemistry , combinatorial chemistry , catalysis , biochemistry , hormone
A rapid method of no‐carrier‐added radiobrominations of A‐ring estrogens has been demonstrated. The method employs N‐chlorosuccinimide and high specific activity sodium bromide‐77 to generate an electrophilic brominating agent, which when reacted with phenolic steroids, yields three primary products. Two of the radiobrominated products have been shown to be the phenolic ortho brominated regioisomers, and the third product is believed to be a reaction intermediate. The use of HPLC afforded a method of separation and isolation of radiobrominated products. The 2‐bromo‐ 77 Br‐ and 4‐bromo‐ 77 Br‐ isomers were found to be quite stable in vitro , where‐as the suspected intermediates were not. A specific activity range of 600‐1200 Ci/mmole and radiochemical yields of 25‐30% were obtained for the 4‐bromo‐ 77 Br regioisomers.