Radical Addition Approach to Asymmetric Amine Synthesis: Design, Implementation, and Comparison of Chiral <i>N</i>-Acylhydrazones
作者:Gregory K. Friestad、Cristian Draghici、Mustapha Soukri、Jun Qin
DOI:10.1021/jo050756m
日期:2005.8.1
construction approach to chiral amines. Here, complete details of the first radical additions to chiral N-acylhydrazones as an approach to asymmetric amine synthesis are disclosed. Novel N-acylhydrazones were designed as chiral CN radical acceptors with Lewis acid activation, restriction of conformational mobility, and commercial availability of precursors. Amination of 4-alkyl-2-oxazolidinones with O-(m
具有无环立体控制的C N键分子间自由基加成作为手性胺的温和,非碱性碳-碳键构建方法提供了极好的潜力。在此,公开了作为不对称胺合成方法的向手性N-酰基hydr的第一自由基加成的完整细节。新型N-酰基hydr被设计为具有路易斯酸活化,构象迁移率限制和前体的商业可获得性的手性C N基团受体。用O-(间甲磺酰基)羟胺或O-(对硝基苯甲酰基)羟胺胺化4-烷基-2-恶唑烷酮,得到N该缩合与醛,得到-aminooxazolidinones Ñ -acylhydrazones 3 - 8。开发了三种合成方法,在路易斯酸促进的C N键分子间自由基加成中实施这些N-酰基hydr 。首先,在ZnCl 2存在下,在氢化锡自由基链条件下,将各种仲和叔烷基碘加到丙醛和苯甲醛(3和7)中,得到N-酰基肼加合物,其非对映体比率为93:7至99:1。一系列N的自由基加成在恶唑烷酮上具有不同取代基的β-酰基hydr表明,与芳