Ti(O i Pr)4存在下格氏试剂对硫酰胺的还原烷基化作用是涉及20种不同底物的研究主题。评估了各种参数的影响,值得注意的是,在某些情况下,通过缓慢添加格氏试剂可以提高这种中等有效方法的收率。该贡献中提供的结果也为拟议的关键中间体(即金属化的亚胺基物种和最终的α-金属化的胺)的反应性提供了新的见识。有趣的是,通过控制温度和所结合的格氏试剂的量,该反应可以被导向选择性地形成前一个钛中间体配合物。这代表了原始方法的扩展,允许通过随后添加亲核试剂来合成各种先前难以接近的取代胺。这种作用不仅可以由有机镁化合物发挥作用,而且还可以由烷基锂试剂,烷基钛(IV)络合物和氢化锂铝发挥。还已经研究了α-金属胺最终中间体的性能,表明该络合物是一种不良的亲核试剂,但可以充当自由基前体,这在所得自由基种类稳定后尤其明显。总的来说,这种化学物质被证明是出乎意料的丰富,并且可以为将来开发新的应用奠定基础。证明该络合
Ti-mediated intramolecular cyclopropanation of N-alkenyl thioamides: scope and mechanistic study
作者:Fabien Hermant、Emmanuel Nicolas、Yvan Six
DOI:10.1016/j.tet.2014.04.006
日期:2014.6
Although thioamides generally undergo a reductive alkylation process when they are treated with a Grignard reagent in the presence of Ti(OiPr)(4), substrates fitted with a but-3-enyl substitution at the nitrogen atom are shown to be converted into bicyclic aminocyclopropanes. These reactions are compared with the similar cyclisations of the corresponding carboxylic amide substrates. A mechanistic study is provided. Coincidently, new reagent systems are identified for the mediation of the same transformation. (C) 2014 Elsevier Ltd. All rights reserved.