Department of Chemistry, University of New Hampshire, Durham, New Hampshire 03824, USA.
J Org Chem. 2012 Jul 20;77(14):5942-55. doi: 10.1021/jo3004925. Epub 2012 Jul 3.
The tandem chain extension-aldol (TCA) reaction of β-keto esters provides an α-substituted γ-keto ester with an average syn:anti selectivity of 10:1. It is proposed that the reaction proceeds via a carbon-zinc bound organometallic intermediate potentially bearing mechanistic similarity to the Reformatsky reaction. Evidence, derived from control Reformatsky reactions and a study of the structure of the TCA intermediate utilizing DFT methods and NMR spectroscopy, suggests the γ-keto group of the TCA intermediate plays a significant role in diastereoselectivity observed in this reaction. Such coordination effects have design implications for future zinc mediated reactions.
β-酮酯的串联链延伸-羟醛（TCA）反应提供了具有平均 syn:anti 选择性为 10:1 的α-取代的γ-酮酯。该反应被认为是通过碳-锌键合的有机金属中间体进行的，该中间体可能与 Reformatsky 反应具有类似的机理。来自控制 Reformatsky 反应和利用 DFT 方法和 NMR 光谱研究 TCA 中间体结构的证据表明，TCA 中间体的γ-酮基团在该反应中观察到的非对映选择性中起着重要作用。这种配位效应对未来的锌介导反应具有设计意义。
