Sapeta Katarina, Kerr Michael A
Department of Chemistry, The University of Western Ontario, London, Ontario, Canada N6A 5B7.
J Org Chem. 2007 Oct 26;72(22):8597-9. doi: 10.1021/jo701606u. Epub 2007 Oct 6.
The cycloaddition of nitrones and enantiomerically pure cyclopropane-1,1-dicarboxylates is examined. Transfer of optical activity to the adduct is dictated by thermal reaction conditions and nature of cyclopropane substitution. Optically active 2-substituted cyclopropane-1,1-dicarboxylates are shown to racemize under typical reaction conditions, providing evidence for a zwitterionic ring-opened intermediate.
对硝酮与对映体纯的环丙烷-1,1-二羧酸酯的环加成反应进行了研究。光学活性向加合物的转移取决于热反应条件和环丙烷取代基的性质。结果表明，光学活性的2-取代环丙烷-1,1-二羧酸酯在典型反应条件下会发生外消旋化，这为两性离子开环中间体提供了证据。
