无溶剂条件下新型功能离子液体催化活性亚甲基化合物与查尔酮的Michael加成研究

以基于DBU(1,8-diazabicyclo[5.4.0]undec-7-ene)的新型功能离子液体[DBU][Ac],[DBU][Lac],[DBU][Tfa],[DBU][n-Pr]和[DBU][n-Bu]为催化剂,研究了无溶剂条件下活性亚甲基化合物与查尔酮的Michael加成反应.反应时间短、收率高、后处理简单、离子液体重复使用6次而活性未发现明显下降.     

微波作用下苯并嗪酮及苯并噻嗪酮的Michael反应

微波照射下苯并口恶嗪酮及苯并噻嗪酮与亲电烯可顺利地发生Ｍｉｃｈａｅｌ反应。反应速度明显增加，反应时间显著减少，９～１０分钟反应即可完成。     

Microwave-Assisted Michael Addition of Diethyl Malonate with Ferrocenyl Substituted Chalcones Under Solvent-Free Conditions

The article describes an efficient, economical, and environmentally friendly approach for Michael addition of diethyl malonate to ferrocenyl substituted chalcones in the presence of microwave irradiation under solvent-free conditions, affording the corresponding Michael adducts in moderate to good yields of 53–94%.

Insight into the Mechanism of the Michael Reaction

The mechanism for the nucleophilic addition step of the Michael reaction between methanethiol as a model Michael donor and several α‐substituted methyl acrylates (X=F, Cl, Me, H, CN, NO₂) as model Michael acceptors is described in detail. We suggest a novel way to condense electrophilic Fukui functions at specific atoms in terms of the contributions from the atomic orbitals to the LUMO or, more generally, to the orbital controlling the reaction. This procedure correctly associates activation energies to local electrophilic Fukui indices for the cases treated in this work. The calculated reaction barriers strongly depend on the nature of the substituent. As a general rule, activation energies are governed by structural changes, although electronic factors are significant for electron‐withdrawing groups. Nucleophilic addition to Michael receptors is best described as a highly nonsynchronous process, in which the geometry of the transition state comprises a nonplanar six‐membered ring. Formation of the S ??? C bond, which defines the interaction between the reactants, progresses ahead of all other primitive processes in the early stages of the transformation. In view of our results, we postulate that highly complex chemical reactions, as is the case for the nucleophilic addition step studied herein, that involve cleavage/formation of a total of six bonds, lower their activation energies by favoring nonsynchronicity, that is, for these types of systems, primitive changes should advance at different rates.     

Modification of Nano-alumina Surface by Michael Addition Reaction

With recent interest in polymer-based nanocomposites, nano-alumina has receivedconsiderable attention because of their high hardness, high strength and good wearresistance. Improvements in mechanical, tribological, conductive and barrier propertiesof some…     

Selective Michael Reaction Controlled by Supersilyl Protecting Group

Selective Michael reaction of organolithium reagents to supersilyl methacrylate is reported. The method was able to control a single and double Michael addition. The successful termination of the process using the supersilyl protecting group allows for the controlled, chemoselective, and diastereoselective Michael reaction.     

迈克尔反应受体分子化学生物学研究

迈克尔受体是烯键或炔键与吸电子基团共轭相连形成的官能团,含有这样官能团的化学小分子能与亲核试剂发生迈克尔加成反应,因此称为迈克尔反应受体分子。迈克尔反应受体分子是一类重要的生理活性分子,它们直接或间接参与许多生命过程,同时也是细胞中许多信号转导途径的调节者,在化学生物学研究中起着重要的作用。本文对迈克尔反应受体分子化学生物学研究进展进行了综述。     

Michael Addition Reaction of Fluorinated Nitro Compounds

The Michael addition reactions of fluorinated nitro compounds with electron deficient olefins to give γ‐fluoro‐γ‐nitro‐esters, nitriles and ketones which bear a fluorinated quaternary carbon center were reported. The reactions were promoted by TMG, affording the desired adducts in acceptable to good yields.     

Alkylation of Amines with Alcohols and Amines by a Single Catalyst under Mild Conditions

An efficient catalytic system for the alkylation of amines with either alcohols or amines under mild conditions has been developed, using cyclometallated iridium complexes as catalysts. The method has broad substrate scope, allowing for the synthesis of a diverse range of secondary and tertiary amines with good to excellent yields. By controlling the ratio of substrates, both mono‐ and bis‐alkylated amines can be obtained with high selectivity. In particular, methanol can be used as the alkylating reagent, affording N‐methylated products selectively. A strong solvent effect is observed for the reaction.     

高分子共混物中Friedel-Crafts烷基化反应原位增容与催化降解机理

采用GPC方法对共混组分的分子量、接枝率和降解度等数据进行分析, 发现AlCl₃催化剂对PS/POE共混物的作用表现在原位增容和催化降解两个方面. 结合Friedel-Crafts烷基化反应的特点细化反应过程, 发现PS/POE共混物在AlCl₃作用下发生接枝反应时, 有大量碳正离子出现, 而碳正离子周围的电子重排会导致分子链断裂, 从而引起共混组分出现大幅度降解. PS/POE/AlCl₃共混物中原位接枝与催化降解是一对竞争性反应, 同时存在, 并相互竞争.     

超临界条件下离子液体催化苯与丙烯烷基化的反应机理研究

用FT-IR和¹H NMR分析KOH无水乙醇溶液滴定前后的盐酸三乙胺无水乙醇溶液, 发现(C₂H₅)₃NHCl中的H具有显著的质子酸性, 且在滴定过程中有KCl生成, 滴定后的¹H NMR谱中δ 7.3处的谱峰完全消失. 将合成的(C₂H₅)₃NHCl/AlCl₃离子液体脱水, 在超临界条件下催化全氘代苯与丙烯的烷基化. 用同位素取代法, 研究了反应机理. 结果表明, 脱水后的离子液体仍然可以催化烷基化反应, 液体产物的GC-MS分析结果支持正碳离子机理. 对比反应前后离子液体的¹H NMR谱图发现, 反应后离子液体中盐酸三乙胺中与N相连H的谱峰强度较反应前降低了80.12%, 可能是引发反应消耗了这部分H.     

有机催化不对称Michael/环化串联反应的研究进展北大核心CSCD

串联反应能够减少反应步骤、简化操作、降低成本、实现高效率转化,符合原子经济性和绿色化学理念.特别是有机催化的不对称串联环化反应以一锅法连续催化多个化学反应,为高效合成多手性中心环状结构提供了新方法.不对称Michael/环化串联反应是构建光学活性状化合物的常用方法之一,近些年,各种有机小分子催化剂应用于不对称Michael/环化串联反应的报道不断增加,并且取得了重大进展.我们根据不同的催化剂类型综述了近5年来关于不对称Michael/环化串联反应的研究进展,并对有机催化不对称Michael/环化串联反应的发展趋势进行了展望.     

Selective Iridium‐Catalyzed Alkylation of (Hetero)Aromatic Amines and Diamines with Alcohols under Mild Reaction Conditions

Selective amine alkylation : A P,N‐ligand‐stabilized iridium complex has been used as an efficient catalyst for the alkylation of (hetero)aromatic amines with alcohols at mild reaction temperatures and catalyst loadings as low as 0.1 mol % Ir (see scheme). The excellent selectivity of the catalyst for monoalkylation of the amine function has also been exploited for the N,N′‐dialkylation of diamines in both symmetric and nonsymmetric fashions.

     

Enantioselectivity Investigation of Short Polar Peptides with Different Positions in the Michael Reaction

This work reports the effectiveness of short polar peptides as asymmetric catalysts in Michael reactions to attain good yields of enantio- and diastereoselective isomers. In a comparison, glutamic acid and histidine produced greater ee and yields when they were applied as the second amino acid in short trimeric peptides. These short polar peptides were found to be efficient organocatalysts for the asymmetric Michael addition reaction in water.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Reaction of Iodolevoglucosenone with Ethyl Cyanoacetate under Michael Reaction Conditions

The reaction of iodolevoglucosenone with the anion of ethyl cyanoacetate via succession of tandem intramolecular reactions leads to formation of tricyclic cyclopropanolevoglucosenone or tetracyclic imine.     

吲哚与亚烷基丙二酸二甲脂Michael加成反应机理的从头算研究

在HF/6-31G(d)水平下, 对吲哚(A)与亚烷基丙二酸二甲脂(B)的Michael加成反应的机理进行了从头算理论研究. 计算结果表明, 该反应的机理为: A＋B→分子复合物→TS1→IM→TS2→产物. 其中第一阶段由复合物经过渡态TS1生成中间体IM, 是C—C键的形成阶段, 该阶段的活化能垒较后一阶段要大, 是该反应的决速步骤; 第二阶段由IM经过渡态TS2生成产物, 完成H迁移和C—H键的形成. 反应过程中, 底物分子中离域化的π键电子的相互作用, 促进了 C—C新键的形成, 同时吲哚的共轭体系遭到部分破坏, 而体系经H迁移使新的C—H键形成后, 吲哚环的共轭体系又得到了恢复. 在MP2/6-311＋G(d,p)水平下, 分别考虑乙醇和1,2-二氯乙烷的溶剂化效应, 单点能计算结果显示, 质子化溶剂对反应的影响较大, 不仅降低了反应的能垒, 且溶剂质子有可能参与了H迁移和C—H键的形成过程, 这一结论与实验结果一致.     

Synthesis of Biphenyl-Based Ligand: Application in Copper-Mediated Chemoselective Michael Reaction

A biphenyl-based ligand attached was synthesized and screened in copper-mediated Michael reaction. The catalyst system works well with carbon or sulfur nucleophiles as Michael donors and cyclohexenone or chalcones as the acceptors under mild and neutral reaction conditions in a chemoselective manner.