An efficient synthesis of (7S,10R)-2-bromo-5,6,7,8,9,10-hexahydro-7,10-epiminocyclohepta[b]indole: application in the preparation and structural confirmation of a potent 5-HT6 antagonist
作者:Matthew L. Isherwood、Peter R. Guzzo、Alan J. Henderson、Ming Min Hsia、Jagjit Kaur、Kassoum Nacro、Venkateswara R. Narreddula、Shailaja Panduga、Rashmi Pathak、Bharat Shimpukade、Valentina Tan、Kai Xiang、Zhu Qiang、Animesh Ghosh
DOI:10.1016/j.tetasy.2012.10.012
日期:2012.12
(7S,10R)-5-Methyl-2-((3-(trifluoromethyl)phenyl)sulfonyl)-5,6,7,8,9,10-hexahydro-7,10-epiminocyclohepta[b]indole 1a is a potent 5-HT6 antagonist (h5-HT6Ki = 1.5 nM) which is derived from an epiminocyclohept[b]indole scaffold. In order to synthesize la on a multi-gram scale to support advanced biological testing, an efficient chiral resolution of the intermediate tert-butyl 2-bromo-5,6,7,8,9,10-hexahydro-7,10-epiminocyclohepta[b]indole-11-carboxylate 2 was developed. After derivatizing 2 with (1R)-(-)-menthyl chloroformate it was found that a single diastereomer 7a could be isolated by selective precipitation from n-hexane. The absolute stereochemistry of 7a was determined by X-ray crystallography and the structure was confirmed as (7S,10R)-tert-butyl 2-bromo-5,6,7,8,9,10-hexahydro-7,10-epiminocyclohepta[b]indole-11-carboxylate. Removal of the chiral auxiliary under basic conditions afforded intermediate 2a in >99% enantiomeric purity and with 80% yield based on recovery from the racemic compound 2. Intermediate 2a was used successfully to synthesize 5-HT6 antagonist la on a multi-gram scale. (C) 2012 Elsevier Ltd. All rights reserved.
(7S,10R)-5-甲基-2-(3-(三氟甲基)苯基) sulfonyl-5,6,7,8,9,10-六氢-7,10-表iminocyclohepta[b]吲哚 1a 是一种强效的 5-HT6 拮抗剂(h5-HT6Ki = 1.5 nM),它来源于一个表iminocyclohepta[b]吲哚骨架。为了在多克级规模上合成 1a 以支持高级生物测试,开发了一种高效的中间体 (R)-(-)-menthyl 氯甲酸酯 2 的手性拆分方法。在使用 (1R)-(-)-menthyl 氯甲酸酯对 2 进行衍生化后,发现可以通过从正己烷中选择性沉淀分离出单一的双相异构体 7a。通过单晶 X 射线衍射确定了 7a 的绝对立体化学,并确认其结构为 (7S,10R)-tert-butyl 2-bromo-5,6,7,8,9,10-hexahydro-7,10-epiminocyclohepta[b]indole-11-carboxylate。在碱性条件下除去手性辅助剂后,获得了 2a 中间体,其对映体纯度超过 99%,基于从消旋化合物 2 中的回收率,获得 80% 的收率。中间体 2a 成功用于多克级 5-HT6 拮抗剂 1a 的合成。© 2012 Elsevier Ltd. 保留所有权利。