环境友好碱有机催化一锅法区域选择性合成新型3,6-二芳基-4-甲基哒嗪（英文）

报道了一种新型三组分反应策略用于区域选择性合成一系列三取代的哒嗪,即于水中进行DABCO催化的苯丙酮、芳香乙二醛一水合物和水合肼三组分缩合反应.该法提供了一种绿色便利的一锅法制备各种芳基取代的3,6-二芳基-4-甲基哒嗪,它以水为溶剂,DABCO为绿色碱有机催化剂,具有高区域选择性、操作简便、产物收率高和后处理简单等优点     

无溶剂锌粉促进下三组分“一锅法”合成1,2-二芳基乙酯

在锌粉的促进下,以芳香醛、溴化苄和酸酐为原料,在无溶剂条件下三组分"一锅法"反应合成了一系列1,2-二芳基乙酯类化合物.该方法具有反应条件温和、操作简单、产率高、原料易得、反应迅速的特点,为合成1,2-二芳基乙酯类化合物提供了一种"绿色"、方便的方法.     

微波辐射促进选择性合成4,6-二芳基-3,4-二氢嘧啶-2(1H)-酮和嘧啶-2(1H)-酮

探讨了在微波加热条件下,芳香醛、取代苯乙酮和尿素的三组分反应在N,N-二甲基甲酰胺(DMF)中制得4,6-二芳基-3,4-二氢嘧啶-2(1H)-酮类化合物,收率为68%～84%.若在反应体系中加入三甲基氯硅烷,该三组分反应则高产率(66%～87%)地生成相应的脱氢产物4,6-二芳基嘧啶-2(1H)-酮类化合物.该反应具有反应条件温和、产物收率高、操作方便等优点,为4,6-二芳基-嘧啶-2(1H)-酮类药物中间体的合成提供了一条全新的路线.     

铜催化腙酰卤与端炔的串联反应制备1,3,5-三取代吡唑衍生物

末端炔烃在亚铜盐的催化条件下,能够与取代芳基腙酰卤通过亲核取代及加成环化的串联反应生成1,3,5-三取代吡唑衍生物.该方法采用易合成的芳基腙酰卤和末端炔烃作为起始原料,在45℃的加热条件下,以绿色溶剂乙腈和水作为反应介质,高产率、区域专一性地生成1,3,5-三取代吡唑产物.而且该反应不受含活泼氢(羟基、羧基等)取代基的影响,通过该方法制备了17种包含不同类型取代基的吡唑衍生物,可作为1,3,5-三取代吡唑类化合物的通用合成法.     

镍催化α,β-不饱和醛的选择性α,β-双芳基化反应

三组分双官能化反应是一种高效、简便构建C―C键、C―X键的方式.双键广泛存在于众多有机化合物中,对双键的双官能化反应研究有巨大的应用潜力.本工作以Ni(COD)2为催化剂,以芳基溴化镁、芳基溴化物为芳基化试剂,实现了3-芳基-2-丙烯醛亚胺中碳碳双键的双芳基化反应.该反应建立了一个新的镍催化α,β-不饱和醛的α,β-双芳基化方法,可以高度区域选择性地向底物分子中引入两个不同取代的芳环,得到多种2,3,3-三芳基丙醛骨架的产物.利用这一反应作为核心步骤实现了天然产物Quebecol的简便合成.机理研究表明,该反应可能经历了亲核加成、金属交换、还原消除的历程.     

离子液体中碘催化下2-氨基苯甲酰肼和4-氧代庚二酸的反应研究

研究了以2-氨基苯甲酰肼和4-氧代庚二酸为原料,以离子液体为绿色溶剂,在碘催化下进行的反应.结果显示,当酰肼中与酰胺基相连上的N原子没有取代基时,会顺利构建三个新环生成哒嗪并[6,1-b]吡咯并[1,2-a]喹唑啉-1,6,9(7H)-酮衍生物,并通过X单晶衍射分析验证了产物2,3,4,5-四氢化-1H,9H-哒嗪并[6,1-b]吡咯并[1,2-a]喹唑啉1,6,9(7H)-三酮(3a)的结构.而当其取代基是芳基时,由于位阻效应,哒嗪环并没有如期关环,生成四氢吡咯并[1,2-a]喹唑啉-3a(1H)-丙酸衍生物.该方法具有合成路线简洁、溶剂绿色环保、操作简便且收率较高等优点.     

碘化钾绿色催化合成4,6-二芳基-3,4-二氢嘧啶-2(1H)-酮（英文）

无溶剂、90℃条件下,碘化钾催化芳香醛、苯乙酮衍生物和脲三组分"一锅法"合成了一系列4,6-二芳基-3,4-二氢嘧啶-2(~1H)-酮。产品结构通过IR,~1H NMR,~(13)C NMR和元素分析进行了确证。提出了可能的催化作用机理。新方法具有反应条件清洁、温和,操作简单,反应时间短,产率高,催化剂绿色、高效等优点。     

室温条件下无溶剂、无催化剂、绿色快速合成8-芳基-5,7,7-三氰基异喹啉衍生物

芳醛、丙二腈和N-取代-4-哌啶酮在室温下,无溶剂、无催化剂反应,方便、快速地合成8-芳基-5,7,7-三氰基异喹啉衍生物.N-乙基-4-哌啶酮是首次应用于合成6-氨基-2-乙基-8-芳基-5,7,7(1H)-三氰基-2,3,8,8a-四氢异喹啉化合物.本方法具有反应条件温和、原料易得、操作简单、产率高、反应时间短,过程绿色等优点.产物的结构经过红外、核磁和高分辨质谱确定.本报道的方法是合成异喹啉类化合物的一条有效途径.     

一种绿色高效合成恶唑烷-2-亚胺的策略

报道了一种绿色高效合成恶唑烷-2-亚胺的策略。首先由N-苄基炔丙胺与对氯苯异氰酸酯经过亲核加成反应合成了芳基取代的炔丙基脲(关环前体)，产率为94.9%；采用更为绿色的InCl₃、ZnI₂为反应试剂，芳基取代的炔丙基脲再经过O-环化异构化反应，合成出对应的恶唑烷-2-亚胺，反应条件为二氯甲烷作溶剂，室温条件下，反应过夜，最终得到较好的产率和收率，产率最高可达81.3%。该工作可为具有恶唑烷-2-亚胺骨架的天然产物的全合成提供一条可选的策略。     

镍催化α,β-不饱和醛的选择性α,β-双芳基化反应

三组分双官能化反应是一种高效、简便构建C―C键、C―X键的方式. 双键广泛存在于众多有机化合物中, 对双键的双官能化反应研究有巨大的应用潜力. 本工作以Ni(COD)₂为催化剂, 以芳基溴化镁、芳基溴化物为芳基化试剂, 实现了3-芳基-2-丙烯醛亚胺中碳碳双键的双芳基化反应. 该反应建立了一个新的镍催化α,β-不饱和醛的α,β-双芳基化方法, 可以高度区域选择性地向底物分子中引入两个不同取代的芳环, 得到多种2,3,3-三芳基丙醛骨架的产物. 利用这一反应作为核心步骤实现了天然产物Quebecol的简便合成. 机理研究表明, 该反应可能经历了亲核加成、金属交换、还原消除的历程.     

Two Different Green Catalytic Systems for One‐Pot Regioselective and Chemoselective Synthesis of Some Pyrimido[4,5‐d]Pyrimidinone Derivatives in Water

In this work, we have developed green and efficient regioselective and chemoselective syntheses of 5‐aryloyl‐1,3‐dimethyl‐7‐thioxo‐5,6,7,8‐tetrahydropyrimido[4,5‐d ]pyrimidine‐2,4(1H ,3H )‐dione and 5‐aryloyl‐1,3‐dimethyl‐2,7‐dithioxo‐2,3,5,6,7,8‐hexahydropyrimido[4,5‐d ]pyrimidin‐4(1H )‐one derivatives via one‐pot three‐component Biginelli‐like condensation of arylglyoxal monohydrates, N ,N‐dimethylbarbituric acid or N ,N‐dimethyl‐2‐thiobarbituric acid, and thiourea in water at 50°C. The presence of two different green catalytic systems (ZrOCl₂.8H₂O and also DABCO) proceeded efficiently to afford the desired products in good‐to‐excellent yields. An aqueous reaction medium, high regioselectivity and chemoselectivity, simple operation and suitable yields of products are the important features of these green protocols.     

Synthesis of β‐Keto Sulfones by a Catalyst‐Free Reaction of Aryldiazonium Tetrafluoroborates,Sulfur Dioxide,and Silyl Enol Ethers

A green approach for the generation of β‐keto sulfones through a reaction of aryldiazonium tetrafluoroborates and sulfur dioxide with silyl enol ether under catalyst‐ and additive‐free conditions has been realized. This reaction proceeds efficiently at room temperature and goes to completion in half an hour. During the reaction process, aryldiazonium tetrafluoroborate is treated with DABCO ⋅ (SO₂)₂ (DABCO=1,4‐diazabicyclo[2.2.2]octane) to provide a sulfonyl radical as the key intermediate, which then initiates the transformation. Oxidants or metal catalysts are avoided, and the presence of DABCO also plays an important role in the reaction.     

A Simple and Efficient Regioselective and Chemoselective Synthesis of New Substituted 3‐Methyl‐6‐arylpyridazine‐4‐carboxamides and 5‐Oxo‐3‐aryl‐5,6‐dihydropyrido[4,3‐c]pyridazine‐8‐carbaldehydes

A facile, green, and one‐pot approach is described for the regioselective synthesis of new substituted 3‐methyl‐6‐arylpyridazine‐4‐carboxamides in water at room temperature. Subsequent treatment of these products with the Vilsmeier reagent led to chemoselective and regioselective production of new 5‐oxo‐3‐aryl‐5,6‐dihydropyrido[4,3‐c]pyridazine‐8‐carbaldehydes in good to excellent yields.     

An Efficient Synthesis and Antibacterial Activity of Some Novel 2‐Azetidinone Derivatives of 4H‐1,2,4‐Triazoles Under Mild Conditions

We have synthesized the novel 2‐azetidinone derivatives by using Schiff bases of 1,2,4‐triazoles via a single step protocol. We used DABCO as a good homogenous, ecofriendly, highly reactive, easy to handle, and nontoxic catalyst. In DABCO catalyzed synthesis of active 2‐oxo‐azetidine, a highly electrophilic ketene intermediate can react with weakly nucleophilic (N═CH) linkage, which is used as the precursor for the cycloaddition reaction to deliver the desired products in excellent yields with protic solvents. In addition, the DABCO as an economically viable and readily available catalyst is soluble in almost all solvents and their salts easily filtered off from the reaction medium. Moreover, this new synthetic protocol features high conversion in green solvents and a straightforward procedure.     

An Environmentally Friendly Method for N‐Methylation of 5‐Substituted 1H‐Tetrazoles with a Green Methylating Reagent: Dimethyl Carbonate

An environmentally friendly method was established for the N‐methylation of the 5‐substituted 1H‐tetrazoles with a green reagent: DMC. DABCO was the optimal catalyst, and hazardous chemicals were avoided in this protocol. A plausible catalytic mechanism is proposed, which consists of a DABCO‐activated process and a thermally induced rearrangement of tetrazole carbamates.     

Rhodium(I)-catalyzed borylation of nitriles through the cleavage of carbon-cyano bonds

The reaction of aryl cyanides with diboron in the presence of a rhodium/Xantphos catalyst and DABCO affords arylboronic esters via carbon-cyano bond cleavage. This unprecedented mode of reactivity for a borylrhodium species allows the regioselective introduction of a boryl group in a late stage of synthesis.     

Silver nanoparticles supported on ionic‐tagged magnetic hydroxyapatite as a highly efficient and reusable nanocatalyst for hydrogenation of nitroarenes in water

A novel chemically modified magnetic hydroxyapatite (MHAp) was prepared and used as support and stabilizer for the synthesis of silver nanoparticles. First, 1,4‐diazabicyclo[2.2.2]octane (DABCO) was successfully grafted onto the surface of MHAp, and then silver nanoparticles were homogeneously loaded on mesoporous MHAp‐DABCO (ionic‐tagged MHAp) nanocomposite by in situ chemical reduction of silver nitrate using sodium borohydride. The structure and properties of the resulting MHAp‐DABCO‐Ag nanocomposite were confirmed using various techniques. The catalytic activity of ionic‐tagged MHAp‐Ag nanocatalyst was investigated for the hydrogenation reaction of nitroarenes in aqueous media. The results reveal that the Ag‐containing inorganic–organic nanocomposite is highly efficient for the reduction of a wide range of aromatic nitro compounds under green conditions. The superparamagnetic nature of the nanocatalyst leads to its being readily removed from solution via application of a magnetic field, and it can be easily stored and reused.     

Engineered mesoporous ionic‐modified γ‐Fe2O3@hydroxyapatite decorated with palladium nanoparticles and its catalytic properties in water

A new mesoporous organic–inorganic nanocomposite was formulated and then used as stabilizer and support for the preparation of palladium nanoparticles (Pd NPs). The properties and structure of Pd NPs immobilized on prepared 1,4‐diazabicyclo[2.2.2]octane (DABCO) chemically tagged on mesoporous γ‐Fe₂O₃@hydroxyapatite (ionic modified (IM)‐MHA) were investigated using various techniques. The synergistic effects of the combined properties of MHA, DABCO and Pd NPs, and catalytic activity of γ‐Fe₂O₃@hydroxyapatite‐DABCO‐Pd (IM‐MHA‐Pd) were investigated for the Heck cross‐coupling reaction in aqueous media. The appropriate surface area and pore size of mesoporous IM‐MHA nanocomposite can provide a favourable hard template for immobilization of Pd NPs. The loading level of Pd in the nanocatalyst was 0.51 mmol g^?1. DABCO bonded to the MHA surface acts as a Pd NP stabilizer and can also lead to colloidal stability of the nanocomposite in aqueous solution. The results reveal that IM‐MHA‐Pd is highly efficient for coupling reactions of a wide range of aryl halides with olefins under green conditions. The superparamagnetic nature of the nanocomposite means that the catalyst to be easily separated from solution through magnetic decantation, and the catalytic activity of the recycled IM‐MHA‐Pd showed almost no appreciable loss even after six consecutive runs.     

Dual nucleophilic catalysis with DABCO for the N-methylation of indoles

DABCO is an extremely active catalyst for the methylation of indoles in conjunction with dimethyl carbonate (DMC). This green chemistry is highly effective and produces N-methylindoles in nearly quantitative yields. The reaction sequence consists of competing alkylation and acylation pathways and involves 1,4-diazabicyclo[2.2.2]octane (DABCO) dually as a nucleophilic catalyst, ultimately resulting in a single product: the N-methylated indole.     

Regioisomeric control induced by DABCO coordination to rotatable self-assembled bis- and tetraporphyrin α,γ-cyclic octapeptide dimers

The design and synthesis of two α,γ-cyclic octapeptides decorated with one and two Zn-porphyrin units in their periphery is described. In nonpolar organic solvents the α,γ-cyclic octapeptides quantitatively self-assemble into Zn-bis- or -tetraporphyrin architectures that could act as molecular tweezers. The self-assembly process, however, is not regioselective and affords a mixture of different regioisomers that are involved in chemical exchange processes. The regioisomers with the Zn-porphyrin units positioned in register with respect to each other are proposed to be the less abundant species in the solution mixture. It has been demonstrated that the coordination of 1,4-diazabicyclo[2.2.2]octane (DABCO) to the supramolecular bis- or tetraporphyrin tweezers is an effective way to achieve regioisomeric control of the self-assembled mixture of dimers. Thus, DABCO functions as an external molecular trigger and, when used under strict stoichiometric control with respect to the Zn-porphyrin units, provokes the exclusive formation of self-assembled dimers with a cofacial arrangement of Zn-porphyrin units through the formation of sandwich-type complexes. The use of excess DABCO fragments the sandwich complexes and affords open dimers of high stoichiometry with DABCO molecules axially monocoordinated to the Zn-porphyrin units, probably as a regioisomeric mixture. In the case of Zn-tetraporphyrin tweezers, the ditopic coordination of DABCO at the two binding sites shows a moderate positive cooperativity factor, αP=5. These assemblies have potential applications as light-induced energy and electron-transfer switches regulated by DABCO coordination; such applications would require the introduction of additional chromophores in the cyclic peptide scaffold.