Domino synthetic strategy for tetrahydrothiophene derivatives from 2-acetylfuran/2-acetylthiophene,benzaldehydes, and sulfur powder

A domino reaction from 2-acetylfuran/2-acetylthiophene, benzaldehydes and sulfur powder has been developed to synthesize a series of tetrahydrothiophene derivatives. The reaction proceeds well to construct five new bonds and a tetrahydrothiophene ring by one-pot. A possible mechanism was proposed, involving a stepwise of Aldol/double Michael addition/internal S_N2 cascaded reaction with sulfur powder acts as a source of sulfur. This method is characterized by mild reaction conditions, commercially available starting materials and transition-metal-free.     

Indium mediated allylation of glyoxylate oxime ethers, esters and cyanoformates

An indium mediated procedure has been developed for the allylation of activated O-functionalised oximes and nitriles as exemplified by a variety of glyoxylate derivatives. This method gives the corresponding free (or protected) amine in a one pot-process. The method is regiospecific and is carried out under remarkably mild conditions so that even oxime esters can be subjected to the typical reaction conditions.     

微波干法催化芳香醛与绕丹宁及N-苯基绕丹宁的缩合反应

利用微波辐射和固体碱性载体试剂催化绕丹宁及N-苯基绕丹宁和芳香醛的缩合反应合成了14个绕丹宁衍生物并研究了影响反应的因素。     

Ultrasound-assisted one-pot synthesis of α-oxycarbanilinophosphonates via a three-component condensation of an aldehyde, diethyl phosphite and an isocyanate under solvent-free conditions

An efficient one-pot method has been developed for the synthesis of α-oxycarbanilinophosphonates via a one-pot reaction of an aldehyde with diethyl phosphite in the presence of magnesium oxide followed by reaction with an isocyanate under solvent-free conditions using ultrasonic irradiation. This method is simple, rapid and good yielding.     

Propargylic amines constructed via copper-catalyzed three-component coupling of terminal alkynes, benzal halides and amines

A method for the synthesis of propargylic amines has been developed via an efficient copper(I)-catalyzed three-component coupling reaction of alkynes, benzal halides and amines through C-H and C-halogen activation. This reaction is conducted under mild conditions and provides an alternative method for the synthesis of propargylic amines.     

A novel efficient method for synthesis of propargylamines via three-component coupling of aryl azide, aldehyde, and alkyne promoted by iron-iodine-copper(I) bromide

A novel, efficient method has been developed for the synthesis of propargylamines through a three-component coupling of aryl azides, aldehydes, and alkynes in the presence of iron-iodine-copper(I) bromide as catalyst. This method is the first example for directly using aryl azides as an amino component in a three-component coupling reaction. Some of the major advantages of this protocol are: good yields, the involvement of a less-expensive and non-toxic catalyst, mild reaction conditions, and a wide range of substrates.     

An efficient, microwave-assisted, one-pot synthesis of indoles under Sonogashira conditions

A microwave-assisted, one-pot, three-component coupling reaction for the synthesis of indoles has been developed. The reaction is carried out in two steps under standard Sonogashira coupling conditions from an N-substituted/N,N-disubstituted 2-iodoaniline and a terminal alkyne, followed by the addition of acetonitrile and an aryl iodide. A variety of polysubstituted indoles have been prepared in moderate to excellent yields using the present method.     

A new, efficient, and simple method for the synthesis of thiiranes from epoxides under solvent-free conditions

A simple, efficient, and new method has been developed for the synthesis of thiiranes from epoxides through a one-pot reaction of epoxides with diethyl phosphite in the presence of ammonium acetate or ammonium hydrogen carbonate/sulfur/ and acidic alumina under solvent-free conditions using microwave irradiation.     

Dehydrogenative Silylation of Alkenes for the Synthesis of Substituted Allylsilanes by Photoredox,Hydrogen‐Atom Transfer,and Cobalt Catalysis

A synergistic catalytic method combining photoredox catalysis, hydrogen‐atom transfer, and proton‐reduction catalysis for the dehydrogenative silylation of alkenes was developed. With this approach, a highly concise route to substituted allylsilanes has been achieved under very mild reaction conditions without using oxidants. This transformation features good to excellent yields, operational simplicity, and high atom economy. Based on control experiments, a possible reaction mechanism is proposed.     

Dehydrogenative Silylation of Alkenes for the Synthesis of Substituted Allylsilanes by Photoredox,Hydrogen‐Atom Transfer,and Cobalt Catalysis

A synergistic catalytic method combining photoredox catalysis, hydrogen‐atom transfer, and proton‐reduction catalysis for the dehydrogenative silylation of alkenes was developed. With this approach, a highly concise route to substituted allylsilanes has been achieved under very mild reaction conditions without using oxidants. This transformation features good to excellent yields, operational simplicity, and high atom economy. Based on control experiments, a possible reaction mechanism is proposed.     

Rapid Optimization of Reaction Conditions Based on Comprehensive Reaction Analysis Using a Continuous Flow Microwave Reactor

Generally, the flow method has the advantage of a precise control over the reaction parameters and a facile modification of the reaction conditions, while a continuous flow microwave reactor allows for the quick optimization of reaction conditions owing to the rapid uniform heating. In this study, we developed a “9+4+1 method” to optimize reaction conditions based on comprehensive reaction analysis using a flow microwave reactor. The proposed method is expected to contribute to the synthesis of various fine and bulk chemicals by reducing cost and wastage, and by conserving time.     

Montmorillonite as a Heterogeneous Catalyst in the Efficient,Mild and One Pot Synthesis of Schiff Bases under Solvent‐Free Conditions

A mild and efficient method has been reported for preparation of Schiff base ligands through condensation reaction of various aromatic aldehydes and ketones with different aromatic amines in the presence of montmorillonite as a heterogeneous catalyst under solvent free conditions. The advantages of this friendly, economically, environmentally and mild method are such as; simplicity of the reaction procedure, reusability of catalyst, simple work‐up, high product yields and very short reaction times.     

A novel pyrrolidine imide catalyzed direct formation of alpha,beta-unsaturated ketones from unmodified ketones and aldehydes

A method for direct, stereoselective preparation of (E)-alpha,beta-unsaturated ketones from ketones and aldehydes, promoted by a novel pyrrolidine imide organocatalyst, has been developed in moderate to high yields. Unlike the Claisen-Schmidt condensation and Lewis acid catalyzed tandem aldol-dehydration processes, this method provides mild reaction conditions to access alpha,beta-unsaturated ketones from simple, unmodified ketones. [reaction: see text]     

Ionic Liquid, [bmim]Br,as an Efficient Promoting Medium for Synthesis of 3-Acetoacetylcoumarin Derivatives Without the Use of Any Catalyst

A series of 3-acetoacetylcoumarin derivatives were synthesized via the reaction of substituted 2-hydroxybenzaldehydes and 4-hydroxy-6-methyl-2H-pyran-2-one in ionic liquid. This method has the advantages of good yields, milder reaction conditions, easier workup, no catalyst, and environmentally benign procedure.     

非均相温和条件下AlCl3/H2SO4高效催化一锅法合成蒽醌衍生物

成功研发了一种与已报道的方法相比合成蒽醌衍生物产量更高的新方法,该方法具有原料易得,收率高,反应时间短,反应条件温和以及操作容易等特点. 合成的蒽醌衍生物的结构由物性数据和光谱结果确定.     

饮料、甜橙、药片和尿液中维生素C的流动注射分析——2,6-二氯吲哚酚光度法

流动注射2,6-二氯吲哚酚光度法测定维生素C具有灵敏,快速的特点,检出限为0.5μg/ml,分析速度120样/h,取Vc 40μg/ml时测量的相对标准偏差为±0.5％。测定各类样品中Vc含量获得较好的结果。     

Green chemistry approaches to the synthesis of 5-alkoxycarbonyl-4-aryl-3,4- dihydropyrimidin-2(1H)-ones by a three-component coupling of one-pot condensation reaction: comparison of ethanol,water, and solvent-free conditions

A general and practical green chemistry route to the Biginelli cyclocondensation reaction using cerium(III) chloride as the catalyst (25% mol) is described under three different sets of reaction conditions. This method provides an efficient and much improved modification of original Biginelli reaction reported in 1893, in terms of high yields, short reaction times, and simple work-up procedure, and it has the ability to tolerate a wide variety of substitutions in all three components, which is lacking in existing procedures.     

Synthesis of 2-(3-amino-2-oxoindolin-3-yl)-3-hydroxynaphthalene-1,4-dione derivatives via a one-pot,three-component reaction under catalyst-free conditions

A concise, facile and straightforward synthetic method has been described for the synthesis of 2-(3-amino-2-oxoindolin-3-yl)-3-hydroxynaphthalene-1,4-dione derivatives by a one-pot, three-component reaction of isatins, 2-hydroxy-1,4-naphthoquinone and ammonium acetate under catalyst-free conditions in ethanol. This protocol becomes highly efficient due to its mild reaction conditions, operational simplicity, and overall good to excellent yields (80–99%).     

One-pot,three-component cascade synthesis of new tetrasubstituted pyrroles by coupling reaction of 2-functionally substituted 2-alkenals,amines, and nitroethane

The reactivity of 2-alkylthio(2-alkoxy)-substituted 3-aryl(hetaryl)propenals in a one-pot, three-component reaction with primary amines and nitroethane has been studied. A method for the synthesis of highly functionalized pyrroles (in 36–80% yield) from 2-alkylthiopropenals has been developed on the basis of this reaction. It is found that the reaction proceeds via formation of the intermediate imine of the starting enal, which undergoes 1,2-addition by nitroethane to give kinetically controlled 2-alkylthio-3-alkylamino-1-aryl(hetaryl)-4-nitropentene. When left to stand, upon heating or under microwave assistance, this adduct can be transformed into the thermodynamically controlled 1,4-adduct. The latter undergoes intramolecular cyclization to afford the target pyrrole. A possibility of such isomerization of addition products of nitroalkane to 2-functionalized α,β-unsaturated imines is revealed for the first time. Scope of the reaction depending upon its conditions as well as structure of the starting substrates and amines has been studied.     

Gold-catalyzed 1,2-migration of silicon, tin, and germanium en route to C-2 substituted fused pyrrole-containing heterocycles

An efficient method for the synthesis of fused pyrroloheterocycles from diverse propargyl-substituted heterocycles in the presence of Au-catalyst has been developed. The cascade transformation proceeds via alkyne-vinylidene isomerization with concomitant 1,2-shift of hydrogen, silyl, and stannyl groups. Remarkably, it was also shown that previously unknown 1,2-migration of a germyl group upon alkyne-vinylidene rearrangement occurs under these reaction conditions. This method allows for mild and efficient synthesis of diverse C-2 substituted N-containing heterocycles.