(+/-)-15-(4-Azidobenzyl)carazolol (2), a potent beta-adrenergic photoaffinity ligand developed in our laboratories, has been radioiodinated to theoretical specific activity (2175 Ci/mmol) and shown to label covalently beta-adrenergic receptor peptides in avian and amphibian erythrocyte membrane preparations. The radioiodinated analogues of the desired compound (2) were optimally prepared by two synthetic steps from (+/-)-15-(4-aminobenzyl)carazolol (8). The latter was iodinated with carrier-free Na125I and chloramine T to yield two major isotopomers (the monoiodinated derivatives 9 and 10), which were separated by thin-layer chromatography and converted via diazonium salt formation to their respective 4-azides, 12 and 6. These azides can be used interchangeably in ligand binding or photoaffinity labeling experiments. Compound 8 was obtained by catalytic reduction of the nitro derivative (7), which was arrived at by direct reaction of 1,1-dimethyl-2-(4-nitrophenyl)ethylamine (3) with 4-(2,3-epoxypropoxy)carbazole (5). Of the desired isomers, (+/-)-15-(4-azido-3-iodobenzyl)carazolol (6) could be synthesized from 1,1-dimethyl-2-(4-azido-3-iodophenyl)ethylamine (4) by direct reaction with 5. This and the preceding sequence of reactions were carried out by using nonradioactive materials, and separation and purification of products were accomplished by high-performance liquid chromatography. The compounds described have been shown to be potent beta-adrenergic antagonists by virtue of their ability to inhibit beta-adrenergic stimulation of adenylate cyclase or to compete for the binding of another beta-adrenergic ligand, [125I]cyanopindolol, to the beta-adrenergic receptors of frog erythrocytes. The photoactive azide derivatives of these compounds (6 and 12) have been shown to covalently incorporate into the beta-adrenergic receptor binding subunit of frog and turkey erythrocyte membrane preparations. Incorporation of the ligands into these polypeptides can be blocked specifically by both beta-adrenergic agonists and antagonists.
(±)-15-(4-
叠氮甲苯基)
咔唑醇(2),是我们实验室开发的一种高效β
肾上腺素能光亲和
配体。该
配体已被放射性
碘标记,达到理论比活度(2175 Ci/mmol),并被证明能够在禽类和两栖类红细胞膜 preparations 中共价标记β
肾上腺素能受体肽。所求化合物(2)的放射性
碘标记物是通过两步合成从(±)-15-(4-
氨基
甲苯基)
咔唑醇(8)最佳制备。后者通过载体缺失的Na125I和
氯胺T进行
碘化,产生两个主要的同位素(单
碘标记的衍
生物9和10),这些衍
生物通过薄层色谱分离,并通过
叠氮盐的形成分别转化为各自的4-
叠氮衍
生物12和6。这些
叠氮化物可以在
配体结合或光亲和标记实验中互换使用。化合物8是通过催化还原硝基衍
生物(7)获得的,这些硝基衍
生物是通过
1,1-二甲基-2-(4-
硝基苯基)乙基胺(3)与4-(2,3-环氧丙基氧基)
咔唑(5)的直接反应得到的。在预期的异构体中,(±)-15-(4-
叠氮-3-
碘甲苯基)
咔唑醇(6)可以通过
1,1-二甲基-2-(4-
叠氮-3-
碘苯基)乙基胺(4)与5的直接反应合成。此反应序列和其他前序反应均采用非放射性材料进行,产物的分离和纯化通过高效
液相色谱完成。这些化合物已被证明是由于其抑制β
肾上腺素刺激的
腺苷酸环化酶的能力,或者是与其他β
肾上腺素配体竞争结合到蛙红细胞β
肾上腺素能受体的能力,从而成为强大的β
肾上腺素拮抗剂。这些化合物的光活性
叠氮衍
生物(6和12)已被证明能够共价结合到蛙和火鸡红细胞膜 preparations 中的β
肾上腺素受体结合亚基。这些
配体与
多肽的结合可以被β
肾上腺素激动剂和拮抗剂特异性阻断。