Highly Diastereoselective Mannich-Type Reactions of Chiral <i>N</i>-Acylhydrazones
作者:Mikkel F. Jacobsen、Liviu Ionita、Troels Skrydstrup
DOI:10.1021/jo0358170
日期:2004.7.1
optimal reaction conditions entailed the simple use of ZnCl2 in acetonitrile at room temperature. Hydrazones derived from phenyl-, isopropyl-, and benzyl-substituted 2-oxazolidinones were examined in the reaction in terms of yield and diastereoselectivity. The facile SmI2-mediated N−N bond cleavage of the formed hydrazines was demonstrated yielding a β-amino acid derivative. Hence, the overall reaction
路易斯酸介导的甲硅烷基烯醇酸酯加到衍生自3-氨基-2-恶唑烷酮的易手性N-酰基hydr衍生物的产率高达71%,非对映体比率为99:1。在大多数情况下,最佳反应条件要求在室温下简单地在乙腈中使用ZnCl 2。在反应中就产率和非对映选择性而言,研究了衍生自苯基,异丙基和苄基取代的2-恶唑烷酮的。便捷的SmI 2所形成的肼的N-N键介导的裂解被证明产生β-氨基酸衍生物。因此,整个反应序列构成有效的不对称曼尼希型反应。非对映选择性的感觉是通过优先攻击手性的较少被屏蔽的Si面并通过X射线晶体学证实的。