在亚胺和磺酰氯的磺胺-施陶丁格环加成中,环选择性主要受磺酰氯的α-取代基的电子效应和亚胺的亲核性控制。具有弱给电子和吸电子取代基的磺酰氯更喜欢[2 s +2 i ]环,形成顺式和反式-β-杜鹃花的混合物。带有强吸电子α-取代基的磺酰氯根据亚胺的亲核性表现出不同的年环选择性,具体如下:(1)取代基比甲基大的弱亲核亚胺仅经历[2 s +2 i ]环化反应,生成反式-β-杜鹃花;(2)具有N-甲基取代基的强亲核亚胺通常同时发生[2 s +2 i ]和[2 s +2 i +2 i ]环化反应,从而传递反式-β-杜鹃花和rel(3 S,5 S由一分子的亚砜和两分子的亚胺组成的,6 R)-1,2,4-噻二嗪烷1,1-二氧化物; (3)更强的亲核环状(Z)-亚胺主要产生[2 s +2 i +2 i ]环,产生一对非对映异构体[2 s +2i +2 i ]年环过氧化物1,2,4-噻二嗪烷1,1-二氧化物。
PASS-predicted design, synthesis and biological evaluation of cyclic nitrones as nootropics
作者:Alka Marwaha、R.K. Goel、Mohinder P. Mahajan
DOI:10.1016/j.bmcl.2007.06.071
日期:2007.9
Out of 400 virtually designed imidazoline N-oxides, five cyclic nitrones were selected on the basis of PASS prediction as potent nootropics and were evaluated for their biological activities in albino mice. The selected N-alkyl and aryl-substituted nitrones were found to be excellent nootropics. A series of lead compounds acting as cognition enhancers have been provided, which can be further exploited in search Of Such New Chemical Entities (NCEs). (c) 2007 Elsevier Ltd. All rights reserved.