Uncatalyzed Three-Component Synthesis of α-Hydrazido Phosphonates
作者:Raquel P. Herrera、David Roca-López、Gloria Navarro-Moros
DOI:10.1002/ejoc.200901337
日期:2010.3
Various α-hydrazidophosphonates have been easily prepared on the basis of the nucleophilic addition of diphenyl phosphite to reactive, preformed N-acylhydrazones and a three-component (aldehydes, N-benzoylhydrazide and diphenyl phosphite) coupling reaction through a non-catalyzed process. An unprecedented and promising enantioselective example of this reaction is also reported.
In the presence of a catalytic amount of scandium triflate [Sc(OTf)3], 4-trifluoromethylbenzoylhydrazones reacted with silyl enolates to afford the corresponding adducts, β-N′-acylhydrazinocarbonyl compounds, in high yields. Reductive cleavage of the nitrogen-nitrogen bond of the hydrazino compounds was performed using Raney Ni under H2 atmosphere, to give β-aminocarbonyl compounds. The two-step process is regarded as a novel Mannich-type reaction using acylhydrazones as electrophiles. Moreover, the hydrazino compounds were also successfully converted to β-lactam, pyrazolidinone, and pyrazolone derivatives.
在催化量的三酸钪[Sc(OTf)3]存在下,4-三氟甲基苯甲酰肼与硅烯醇酯发生反应,得到相应的加合物δ-N′-酰肼羰基化合物,产量很高。在 H2 气氛下,使用 Raney Ni 对肼基化合物的氮-氮键进行还原裂解,得到δ-氨羰基化合物。这一两步反应被视为以酰基肼为亲电体的新型曼尼希式反应。此外,肼类化合物还成功地转化成了 δ-内酰胺、吡唑烷酮和吡唑酮衍生物。
A Simple and General Chiral Silicon Lewis Acid for Asymmetric Synthesis: Highly Enantioselective [3 + 2] Acylhydrazone−Enol Ether Cycloadditions
作者:Seiji Shirakawa、Pamela J. Lombardi、James L. Leighton
DOI:10.1021/ja052307+
日期:2005.7.1
A highly diastereo- and enantioselective [3 + 2] acylhydrazone-enolethercycloaddition mediated by a simplechiralsilaneLewis acid is described. The reactions are highly practical, as demonstrated by a larger scale (5 g of the hydrazone) reaction in which the product was obtained after recrystallization in 93% yield and 99% ee. Evidence for a stepwise mechanism and a model for the asymmetric induction
描述了由简单的手性硅烷路易斯酸介导的高度非对映选择性和对映选择性 [3 + 2] 酰基腙烯醇醚环加成。这些反应是非常实用的,正如更大规模(5 g 腙)反应所证明的那样,其中重结晶后以 93% 的产率和 99% 的 ee 获得产物。还提供了逐步机制的证据和非对称归纳模型。
Mannich Type Reactions of Acylhydrazones with Silyl Enolates for the Synthesis of b-Amino Ester, b-Amino Ketone, b-Lactam, Pyrazolidinone, and Pyrazolone Derivatives