Acidic-functionalized ionic liquid as an efficient, green and reusable catalyst for hetero-Michael addition of nitrogen, sulfur and oxygen nucleophiles to α,β-unsaturated ketones
作者:Feng Han、Lei Yang、Zhen Li、Chungu Xia
DOI:10.1039/c1ob06346d
日期:——
A series of acidic-functionalized ionic liquids were synthesized and applied to the hetero-Michael addition of nitrogen, sulfur and oxygen nucleophiles to α,β-unsaturated ketones under solvent-free conditions. Notably, 1-methylimidazoliump-toluenesulfonic ([Hmim]OTs) was found to be the most efficient catalyst and could realize âhomogeneous catalysis, two-phase separationâ. Additionally, the catalytic system has wide substrate scope and good to excellent yields (up to 99%) could be obtained at room temperature.
Fluoroboric acid adsorbed on silica-gel (HBF4–SiO2) as a new, highly efficient and reusable heterogeneous catalyst for thia-Michael addition to α,β-unsaturated carbonyl compounds
作者:Gaurav Sharma、Raj Kumar、Asit K. Chakraborti
DOI:10.1016/j.tetlet.2008.04.144
日期:2008.6
found to be a new and highly efficient heterogeneouscatalyst for thia-Michael addition to α,β-unsaturated carbonyl compounds under solvent-free conditions. In the case of 1,3-diaryl-2-propenones, the reactions are best carried out in MeOH. The rate of thia-Michael addition was dependent on the steric hindrance at the β-carbon of the α,β-unsaturated carbonyl substrate as well as surrounding the thiol
Asymmetric ruthenium-catalyzed 1,4-additions of aryl thiols to enones
作者:Andrei Bădoiu、Gerald Bernardinelli、Céline Besnard、E. Peter Kündig
DOI:10.1039/b918877k
日期:——
bind and activate α,β-unsaturated carbonyl compounds for cycloadditionreactions. These mild Lewisacidscatalyzeasymmetric 1,4-addition reactions of aryl thiols to enones with product selectivities up to 87% ee. 31P NMR experiments provide an insight into the intricate equilibria governing the reaction mechanism. The absolute configuration of the major products indicates enones to react in the syn-s-trans
定义明确,稳定的单点绑定 钌配合物1和2选择性地结合并活化α,β-不饱和羰基化合物以进行环加成反应。这些温和的路易斯酸催化芳基硫醇与烯酮的不对称1,4-加成反应,产物选择性高达ee的87%。31 P NMR实验提供了控制反应机理的复杂平衡的见解。主要产品的绝对构型表示烯酮的反应合成- S ^ -反式方向。基于Ru配合物的X射线结构的模型可用于合理化选择性。
Free bases of chiral N-substituted porphyrins as catalysts for asymmetric reaction
作者:Akihiko Ito、Katsuaki Konishi、Takuzo Aida
DOI:10.1016/0040-4039(96)00376-0
日期:1996.4
Chiral N-substituted porphyrin free bases having a conformationally locked asymmetric nitrogen atom catalyzed Michael addition of thiophenols to cycloalkenones, where the reaction proceeded enantioselectively when the catalyst having a xylylene strap anchored via two secondary amido linkages (2) was employed.
Green Protocol for Conjugate Addition of Thiols to α,β-Unsaturated Ketones Using a [Bmim]PF<sub>6</sub>/H<sub>2</sub>O System
作者:J. S. Yadav、B. V. S. Reddy、Gakul Baishya
DOI:10.1021/jo034335l
日期:2003.9.1
Alpha,beta-unsaturated ketones undergo conjugate addition rapidly with thiols in a hydrophobic ionic liquid [bmim]PF(6)/H(2)O solvent system (2:1) in the absence of any acid catalyst to afford the corresponding Michael adducts in high to quantitative yields with excellent 1,4-selectivity under mild and neutral conditions. The enones show enhanced reactivity in ionic liquids, thereby reducing reaction