氮杂偶联加成反应的研究

氮杂偶联加成反应是一类在近十年里才受到重视的原子经济性新反应, 尤其是在近几年里许多有效的合成方法不断被发展和研究. 系统总结了各种氮源参与的氮杂偶联加成反应的研究进展.     

Microwave-Induced Aza-Michael Reaction in Water: A Remarkably Simple Procedure

Microwave-induced fast addition of several amines to conjugated carbonyl compounds has been carried out in water very efficiently in the absence of any catalyst.     

Green Aza-Michael Reaction of Aliphatic Amines to á,(a)-Unsaturated Compounds in Water

The hydroamination of olefins is a long-standing goal for transition metal catalysis. And the metal-catalyzed addition of amines to carbon-carbon double bonds is an unsolved, synthetically important problem. Although recent advances have made using lanthanide and precious metal complexes, there are few excellent catalyst that display broad functional group tolerance and useful rates for an intermolecular aza-Michael addition. As such, the development of efficient synthetic methods leading to a-amino carbonyl compounds and derivatives has attracted much attention in organic synthesis. Although recent advances have made this route more attractive, development of cheaper, simpler, and more efficient metal catalyst is highly desirable. We also have been interested in developing a reaction that uses catalytic quantities of minimally toxic, readily available, economic reagent should greatly contribute to the creation of environmental benign processes.The recent interest in aqueous medium metal-mediated carbon-carbon and carbon-heteroatom and formations led to the contributors for such reactions. Furthermore, development of organic reactions in water will contribute to the progress of green and quasi-nature catalysis chemistry. Surprisingly however, there is few report on conjugate additions of amines to a,a-unsaturated carbonyl compounds in water.Herein, we report a new protocol that employs air stable copper salts as efficient catalyst in the aza-Michael reaction under mild reaction conditions. Advantages of the protocol include high-yielding reactions that can be conducted at ambient temperature; the use of readily available and stable copper salts as the catalyst, and the reaction was successfully performed in environmental benign solvent, water.Finally, we have utilized a variety of aliphatic amines successfully with different á,(a)-unsaturated compounds catalyzed by simple hydrophilic ionic liquid, bmimBF4 in water. Interestingly, all the aliphatic amines gave almost quantitative in yield with á,(a)-ethylenic compounds. The present reactions with its mild reaction conditions open a novel entry to synthesis of a-amino carbonyl compounds by simple procedure.     

水相Reformatsky反应研究进展

近30年来,在水介质中形成碳-碳键一直是有机合成的研究热点.本文综述了水相中Reformatsky反应的研究进展,并对反应机理和应用作了简要的阐述.     

Vanadyl(IV) Acetate: An Efficient,Reusable Heterogenous Catalyst for Aza-Michael Reaction Under Solvent-Free Conditions

Vanadyl(IV) acetate [VO(OAc)₂] efficiently catalyzes the conjugate addition of aliphatic, aromatic amines to α,β-unsaturated carbonyl compounds in solvent-free media at room temperature to afford corresponding amino compounds in good to excellent yields. The catalyst can be recovered and reused for further cycles.     

Efficient Lewis Acids Catalyzed Aza-Michael Reactions of Enones with Carbamates

The β-amino carbonyl functionality is not only a segment of biologically important natural products but also a versatile intermediate for the synthesis of nitrogen-containing compounds.1 The development of novel synthetic methods leading to β-amino ketone, β-amino acids or their derivatives has attracted much attention in organic synthesis.2 Among the traditional methods for generating β-amino carbonyl compounds, Mannich-type reaction is one of the classical and powerful methods.3 However,…     

Synthesis of Azaspiro Tricyclic Scaffolds through Post-Ugi Modifications: Scope and Limitation of Aza-Michael Cyclization

Post-Ugi modifications offer a great tool to construct functionalized heterocycles in an atom-economic manner. Using this approach, we have constructed highly functionalized azaspiro tricyclic scaffolds that involve Ugi condensation and ipso-cyclization followed by aza-Michael ring closures. Herein, we present a detailed account of aza-Michael cyclizations with respect to substrate scope and limitations, along with new methods to prepare novel azaspiro tricyclic scaffolds.     

PEG-SO3H as a Catalyst for the Preparation of Bis-Indolyl and Tris-Indolyl Methanes in Aqueous Media

A facile, efficient, and green synthesis of bis-indolyl and tris-indolyl methanes has been developed by one-pot condensation of indole with structurally diverse aldehydes and ketones in the presence of poly(ethylene glycol)–bound sulfonic acid as catalyst at room temperature.     

Imidazole-Catalyzed Henry Reactions in Aqueous Medium

2-Nitroalkanols can be efficiently synthesized using imidazole as a mild Lewis basic catalyst in aqueous medium as well as in organic solvents. The products have been found in good yields without purification (> 95% purity by ¹H NMR) for aromatic aldehydes. Additionally, the very mild reaction conditions prevent the particular side reactions such as aldol condensation, Cannizzaro reaction, or dehydration of the 2-nitro alcohols into nitro alkenes even if aromatic aldehydes are used. This report satisfies the criteria for green synthesis in terms of reaction medium and recycling of the catalyst (imidazole).     

Ultrasonic-enhanced Stereoselective Debromination of vic-Dibromides to Alkenes with Metallic Zinc Powder in Aqueous Media

IntroductionThe protection/deprotection procedures play avery important role in organic syntheses[1,2 ] .Car-bon- carbon double bond functional groups are oftenprotected during reactions because of their reactivi-ty.A variety of protecting methods,such as halo-genation,epoxidation and the method of usingC5H5Fe( CO) 2 BF4as the blocking group have beenrecommended for this purpose[3 _ 5] .Among themethods,protection/deprotection of olefins viabromination/debromination is more popular,sim-pler…     

L-Prolinamide Catalyzed Aqueous Direct Aldol Reaction： an Environment-friendly Method for the Synthesis of β- Hydroxyl keto nes

An environment-friendly L-prolinamide catalyzed aldol reaction has been developed. The reaction exhibited broad substrate generality, and high yields with good diastereoselectivity were obtained for cyclic ketones.The simplicity of product isolation, usage of water as environmentally benign reaction medium, and the usage of cheap, readily available and recyclable catalyst make this process promising to be developed for large-scale preparation of β-hydroxyl ketones.     

金属参与的水相烯丙基化反应

近30年来,水介质中碳-碳键的形成一直是研究的热点,其优越性也逐渐被人们所认知。在已发现的水相金属有机反应中,水相烯丙基化反应是研究得较多和较深入的反应之一。水相烯丙基化反应由于其发展速度较快,新的金属及金属体系参与的烯丙基化反应以及水相烯丙基化反应的机理研究不断被报道。本文综述了水相中金属参与烯丙基化反应的最新研究进展,并对新的反应机理作了简要的阐述。     

EcoFriendly Synthesis of Tetrahydropyrimidine Derivatives in Aqueous Medium Under Ultrasonic Irradiation

Abstract

A simple, efficient, and ecofriendly procedure was developed for the synthesis of 2-substituted 1,4,5,6-tetrahydropyrimidine derivatives catalyzed by N-bromosuccinimide using ultrasonic irradiation in aqueous medium. Prominent advantages of this new method are good yields, aqueous medium, short reaction times, and easy workup procedure. The compounds were characterized by infrared, NMR, liquid chromatography–mass spectrometry, and elemental analyses.     

Catalyst‐Free Reaction in Water: Synthesis of Functionalized Tetrahydroindole Derivatives via Three‐Component Domino Reaction

An environmentally benign and efficient method has been developed for the synthesis of functionalized tetrahydroindole derivatives in aqueous media under catalyst‐free conditions, by simply combining a phenylglyoxal monohydrate, an enaminone, and a barbituric acid. The advantages of this method are that it is catalyst free, has an easy workup, provides good yields, and uses water as solvent, which make this procedure facile and practical.     

环烯丙基溴在Cu/SnCl2参与的水相羰基烯丙基化反应中的应用

Five- and six-membered cyclic allylic halides were found to be much less reactive than the acyclic allylic halides in aqueous allylation reactions. Nevertheless, it was found that SnC12/Cu was powerful enough to mediate the aqueous allylation reactions involving cyclic allylic halides. Both the aliphatic and aromatic aldehydes could be efficiently allylated and the reaction condition was mild, simple and safe. The yields were usually in 75%-97% and the reaction was erythro selective.     

基于绿色化学的甲烷与氯气取代反应装置优化设计

针对传统甲烷与氯气取代反应实验装置存在环境不友好、实验装置较大、过于分散、反应难以定量化等缺陷,从绿色化学角度出发,对传统甲烷与氯气取代反应装置进行优化设计,实现了该实验过程的绿色化,实验装置的微型化、综合化和反应的可控化、定量化。     

含分子内氢键的苯硫酚在水相中的Michael加成反应

苯硫酚的巯基是一个较强的亲核基团,对α,β-不饱和双键的Michael加成反应已有报道．但是当巯基的邻位存在与其形成氢键的基团时,如果按文献条件进行反应,或者反应无法进行,或者要使用反应条件苛刻的丁基锂,或者使用吡啶等毒性较大的反应溶剂,而且产率较低．本文选择     

Two-Dimensional Conjugated Polymer Synthesized by Interfacial Suzuki Reaction: Towards Electronic Device Applications

Preparing two-dimensional conjugated polymers (2DCPs) with desirable structures and semiconducting properties is promising but remains a great challenge. Presented here is a new 2DCP, named 2D polytriethyltriindole (2DPTTI), which is efficiently synthesized by a modified interfacial Suzuki reaction from 2,7,12-tribromo-5,10,15-triethyltriindole (2-BrTTI) and 1,4-benzenediboronic acid dipinacol ester (BADE) precursors at room temperature. Wafer-scale free-standing 2DPTTI films with controllable thicknesses between 2.5 and 46.0 nm were obtained by adjusting the experimental conditions. The resulting 2DPTTI films, used as an active layer in organic field effect transistors (OFETs), exhibited typical p-type semiconducting properties and superior UV optoelectronic performance with a photosensitivity of 3.7×10³ and responsivity of 1.4×10³ A W⁻¹, as well as a light-blue fluorescence character. This report provides a general approach for constructing various semiconducting 2DCPs, by an interfacial Suzuki reaction, towards multifunctional organic electronics.     

Titanium Salan Catalysts for the Asymmetric Epoxidation of Alkenes: Steric and Electronic Factors Governing the Activity and Enantioselectivity

A new insight into the highly enantioselective (up to >99.5 % ee) epoxidation of olefins in the presence of chiral titanium(IV) salan complexes is reported. A series of 14 chiral ligands with varying steric and electronic properties have been designed, and it was found that electronic effects modulate the catalytic activity (without affecting the enantioselectivity), whereas the steric properties account for the enantioselectivity of the epoxidation. Competitive oxidations of p‐substituted styrenes reveal the electrophilic nature of the oxygen‐transferring active species, with a Hammett ρ value of ?0.51; the enantioselectivity is unaffected by the electron‐donating (or withdrawing) ability of the p‐substituents. Mechanistic studies provide evidence in favor of a stepwise reaction mechanism: in the first (rate‐determining) stage, olefin most probably coordinates to the active species, followed by intramolecular enantioselective oxygen transfer. The enantioselectivity increases with decreasing temperature. The modified Eyring plots for the epoxidation of styrene and (Z)‐β‐methylstyrene are linear, indicating a single, enthalpy‐controlled mechanism of stereoselectivity, with ΔΔH^≠=?6.6 kJ mol^?1 and ?5.4 kJ mol^?1, respectively.     

Two‐Dimensional Conjugated Polymer Synthesized by Interfacial Suzuki Reaction: Towards Electronic Device Applications

Preparing two‐dimensional conjugated polymers (2DCPs) with desirable structures and semiconducting properties is promising but remains a great challenge. Presented here is a new 2DCP, named 2D polytriethyltriindole (2DPTTI), which is efficiently synthesized by a modified interfacial Suzuki reaction from 2,7,12‐tribromo‐5,10,15‐triethyltriindole (2‐BrTTI) and 1,4‐benzenediboronic acid dipinacol ester (BADE) precursors at room temperature. Wafer‐scale free‐standing 2DPTTI films with controllable thicknesses between 2.5 and 46.0 nm were obtained by adjusting the experimental conditions. The resulting 2DPTTI films, used as an active layer in organic field effect transistors (OFETs), exhibited typical p‐type semiconducting properties and superior UV optoelectronic performance with a photosensitivity of 3.7×10³ and responsivity of 1.4×10³ A W^?1, as well as a light‐blue fluorescence character. This report provides a general approach for constructing various semiconducting 2DCPs, by an interfacial Suzuki reaction, towards multifunctional organic electronics.