Unexpected Four-Membered over Six-Membered Ring Formation during the Synthesis of Azaheterocyclic Phosphonates: Experimental and Theoretical Evaluation
作者:Veronique Van Speybroeck、Kristof Moonen、Karen Hemelsoet、Christian V. Stevens、Michel Waroquier
DOI:10.1021/ja0584119
日期:2006.7.1
studied on both experimental and theoretical grounds. In a recently described route to phosphono-beta-lactams [Stevens C. V.; Vekemans, W.; Moonen, K.; Rammeloo, T. Tetrahedron Lett. 2003, 44, 1619], it was found that starting from an ambident allylic anion only four-membered rings were formed without any trace of six-membered lactams. New anion trapping experiments revealed that the gamma-anion is highly
在实验和理论基础上研究了官能化氨基膦酸酯的环化。在最近描述的磷酸-β-内酰胺途径中 [Stevens CV; 维克曼斯,W.;穆宁,K.;Rammeloo, T. Tetrahedron Lett。2003, 44, 1619],发现从环境烯丙基阴离子开始,仅形成四元环,而没有任何六元内酰胺的痕迹。新的阴离子捕获实验表明,γ-阴离子在分子间反应中具有高度反应性。从头算计算预测,由于围绕 CN 键的旋转受限以及闭环过程中的高度应变过渡态,γ-阴离子的反应势垒更高。钠或锂反离子、明确的二甲醚溶剂分子和本体溶剂效应在不同的理论水平上都得到了适当的考虑。