School of Chemistry and Molecular Bioscience, University of Queensland, St. Lucia, Brisbane, QLD 4067, Australia.
J Org Chem. 2010 Nov 5;75(21):7322-31. doi: 10.1021/jo101590t.
An extensive density functional theory (DFT, M05-2X) investigation has been performed on the zinc carbenoid-mediated homologation reaction of β-keto esters. The mechanistic existence of a classical donor-acceptor cyclopropane intermediate was probed to test the traditional school of thought regarding these systems. Calculations of the carbenoid insertion step, following enolate formation, unmasked two possible pathways. Pathway B was shown to explain the proposed, but spectroscopically unobservable donor-acceptor cyclopropane intermediate, while the second (pathway A) reveals an alternative to the classical intermediate in that a cyclopropane transition state leads to product.
采用密度泛函理论（DFT，M05-2X）对锌卡宾介导的β-酮酯同系化反应进行了广泛研究。探测了经典的给体-受体环丙烷中间体的存在来检验这些体系的传统观念。烯醇化物形成后，对卡宾插入步骤的计算揭示了两种可能的途径。途径 B 被证明可以解释所提出的，但光谱上不可观察的给体-受体环丙烷中间体，而第二种途径（途径 A）则提供了经典中间体的替代方案，即环丙烷过渡态导致产物生成。
