Catalytic Hunsdiecker Reaction and One-Pot Catalytic Hunsdiecker–Heck Strategy: Synthesis of α,β-Unsaturated Aromatic Halides, α-(Dihalomethyl)benzenemethanols, 5-Aryl-2,4-pentadienoic acids, Dienoates and Dienamides
作者:Dinabandhu Naskar、Sujit Roy
DOI:10.1016/s0040-4020(99)01035-2
日期:2000.3
The reaction of α,β-unsaturated aromatic (or heteroaromatic) carboxylic acids with N-halosuccinimides (1 equiv.) and catalytic tetrabutylammonium trifluoroacetate (0.2 equiv.) in dichloroethane results in facile halodecarboxylation affording the corresponding (E)-halides in good to excellent yields. A similar reaction, but with 2 equiv. of N-halosuccinimides in acetonitrile-water (1:1 v/v) results
α,β-不饱和芳族(或杂芳族)羧酸与N-卤代琥珀酰亚胺(1当量)和催化四丁基三氟乙酸铵(0.2当量)在二氯乙烷中的反应导致容易的卤代羧化,从而得到相应的(E)-卤化物优异的产量。类似的反应,但具有2当量。的N在乙腈-水中(1-1:1 v / v)中的-卤代琥珀酰亚胺导致相应的α-(二卤代甲基)苯甲醇的排他性形成。此外,已开发出一种结合了Hunsdiecker催化反应(在二氯乙烷中使用三氟乙酸四丁基铵)和Heck偶联(使用乙酸钯/三乙胺/三苯基锑/二氯乙烷)的一锅法,用于合成5-芳基-2,4-戊二烯酸,酯和酰胺,产率中等至良好。通过上述途径合成了天然产物胡椒碱和哌瓜胺。机理和理论研究(通过AM1计算)对当前的卤代羧化反应的机理提供了有用的见解,表明离子途径涉及卤离子跨碳-碳双键的攻击,
Iron‐Catalyzed Cross‐Coupling of Alkynyl and Styrenyl Chlorides with Alkyl Grignard Reagents in Batch and Flow
Transition-metal-catalyzed cross-coupling chemistry can be regarded as one of the most powerful protocols to construct carbon-carbon bonds. While the field is still dominated by palladium catalysis, there is an increasing interest to develop protocols that utilize cheaper and more sustainable metal sources. Herein, we report a selective, practical, and fast iron-based cross-coupling reaction that enables
New Highly Nucleophilic and Practically Accessible Chlorocarbenoids for Carbonyl Olefination
作者:Chia-Chung Tsai、Ching-Ting Chien、Yu-Cheng Chang、Huan-Chang Lin、Tu-Hsin Yan
DOI:10.1021/jo050455c
日期:2005.7.1
bimetallic species resulted in the generation of a highly nucleophilic and practically convenient chloromethylenetitanium complex, which efficiently effected condensation even with enolizable or inert carbonyl compounds, such as sterically congested ketones, to provide vinyl chloride compounds.
Chloroalkenes, important building blocks for cross-coupling reactions, are prepared in one step by the Suzuki reaction of 1,1-dichloroethylene and 1,2-dichloroethylene with alkenyl- and arylboronic acids. Under the proper reaction conditions, it is possible to obtain the monocoupling reaction to provide the corresponding chloroalkenes with good yields. This method represents an excellent route for
Is metal necessary in the Hunsdiecker-Borodin reaction?
作者:Dinabandhu Naskar、Shantanu Chowdhury、Sujit Roy
DOI:10.1016/s0040-4039(97)10639-6
日期:1998.2
The tetrabutylammonium trifluoroacetate (TBATFA) catalyzed conversion of alpha,beta-unsaturated carboxylic acids to the corresponding halides with N-halosuccinimides in dichloroethane is reported as the first example of a metal-free catalytic version of the title reaction The methodology was further employed for a facile synthesis of piperine. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.