Solid supported chiral auxiliaries in asymmetric synthesis. Part 2: Catalysis of 1,3-dipolar cycloadditions by Mg(II) cation
作者:Giuseppe Faita、Alfredo Paio、Paolo Quadrelli、Fabio Rancati、Pierfausto Seneci
DOI:10.1016/s0040-4020(01)00769-4
日期:2001.9
oxides and nitrones in the presence of Mg(II) cation as catalyst were evaluated. The presence of acetonitrile as co-solvent was found to be fundamental for the Lewis acid catalysis on solid-phase. The regio- and stereochemical outcome of nitrile oxide cycloadditions is influenced by nearly stoichiometric quantities of the cation, whilst catalytic amounts of Mg(II) influence both the reactivity and the
在Mg(II)阳离子作为催化剂的情况下,评估了负载的Evans手性助剂与腈氧化物和硝酮的1,3-偶极环加成反应。发现乙腈作为助溶剂的存在是固相路易斯酸催化的基础。一氧化氮环加成的区域和立体化学结果受接近化学计量的阳离子的影响,而催化量的Mg(II)影响硝酮环加成的反应性和立体选择性。获得的结果支持了涉及Mg(II)与手性助剂的二羰基片段的配位的反应机理。