StereoselectiveSimmons-Smith cyclopropanation of chiral enamides.
StereoselectiveSimmons-Smith cyclopropanation of chiral enamides.
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DOI：
10.1002/anie.200700681
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发表时间：
2007-05
影响因子：
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通讯作者：
Zhenlei Song;Ting Lu;R. Hsung;Z. Al-Rashid;Changhong Ko;Yu Tang
中科院分区：
文献类型：
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作者：
Zhenlei Song;Ting Lu;R. Hsung;Z. Al-Rashid;Changhong Ko;Yu Tang
与胺类不同的是，胺类化合物在合成中仍然相对模糊。[1,2]胺类化合物的有限使用可能部分是由于难以合成；然而，最近在铜和钯催化的N烯基化[3,4]方面的进展应该引起人们对基于使用酰胺作为多功能构建块的合成方法的开发的强烈兴趣。在值得注意的研究中，有报道称酰胺类化合物的正电按需Diels-Alder环加成[6]和反电按需杂电按需Diels-Alder环加成[7]。我们报道了手性酰胺在合成手性α-羟基半胺中的环氧化反应(1！方案1中的2)[8,9]。在这种环氧化反应中，高水平的非对映选择性是令人惊讶的，这使我们推测漆胺1可能有利于A中所示的构象，[8,9]，这为观察到的立体化学结果提供了良好的π-面偏倚。
Enamides, unlike enamines, have remained relatively obscure in synthesis.[1, 2] The limited use of enamides could be due in part to synthetic inaccessibility; however, recent developments in copper-and palladium-catalyzed N alkenylation [3, 4] should provoke a strong interest in the development of synthetic methods based on the use of enamides as versatile building blocks. Among notable studies,[5] there have been reports of both normal-electron-demand Diels–Alder cycloadditions [6] and inverse-electron-demand hetero-Diels–Alder cycloadditions [7] of enamides. We reported the epoxidation of chiral enamides in the synthesis of chiral α-hydroxyhemiaminals (1! 2 in Scheme 1).[8, 9] The high level of diastereoselectivity in this epoxidation was surprising and led us to speculate that enamides 1 could favor the conformation shown in A,[8, 9] which provides an excellent π-facial bias for the observed stereochemical outcome.