Design and synthesis of an aminobenzo-15-crown-5-labeled estradiol tethered with disulfide linkage

A novel measuring method (electroimmunoassay) of 17beta-estradiol (E,) in urine or blood was proposed on the basis of a competition between E-2 and a labeled E-2 against an immobilizing antibody. To evaluate the principle, 3-{4-[17beta-hydroxy-1,3,5(10)-estratrien-3-yloxy]butyldisulfanyl}-N-(6,7,9,10,12,13,15,16-octahydro-5,8,11,14,17-pentaoxabenzocyclopentadecen-2-yl) succinamic acid (1) was designed and synthesized as a novel aminobenzo-15-crown-5-containing E-2 tethered with disultide linkage. Two thiol-intermediates 5b and 19c were efficiently synthesized from mercaptosuccinic acid 7 and 4,4-dithiodibutyric acid 12, respectively. Formations of disulfide linkages from less reactive thiols were examined and 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) could be employed for the formation of an unsymmetrical disulfide 20c from 5b and 19c. Then, removal of TMS- and allyl-protecting groups in 20c successfully afforded the crown ether-containing E-2 1. (C) 2004 Elsevier Ltd. All rights reserved.