Highly efficient and catalyst-free synthesis of unsymmetrical thioureas under solvent-free conditions

A highly efficient and simple synthesis of unsymmetrical thioureas is reported based on the reaction of readily synthesized dithiocarbamates with amines, without using any catalyst under solvent-free conditions. The short reaction time, high yields, and solvent-free conditions are advantages of this method. We did not observe the formation of any symmetric disubstituted thiourea, under these reaction conditions.     

An efficient method for the N-formylation of amines under catalyst- and additive-free conditions

A simple catalyst- and additive-free method for the N-formylation of amines has been developed. The advantages of this protocol include a wide range of functional group tolerance, high efficiency and a lack of required extra promoters under mild conditions. This convenient strategy will provide a facile synthesis towards N-formamide natural products and pharmaceutical derivatives. A mechanism that involves difluorocarbene is proposed for this reaction.     

A new sustainable protocol for the synthesis of nitroaldol derivatives via Henry reaction under solvent-free conditions

A new protocol for the Henry addition of nitroalkanes to aryl- and alkyl-aldehydes promoted by PS-BEMP under solvent-free conditions (SolFC) is presented. The corresponding nitroaldol products were obtained in good yields and short times; furthermore minimization of the reaction waste was achieved by reducing the use of organic solvents. Extension of the protocol was obtained by setting up the tandem Michael-Henry reaction of α,β-unsaturated aldehydes and nitroalkane to yield the corresponding dinitro derivatives.     

An unexpected, novel, three-component reaction between isoquinoline, an isocyanide and strong CH-acids in water

An unexpected three-component condensation reaction between an isocyanide, isoquinoline and a strong CH-acid efficiently provides 1,2-dihydroisoquinoline derivatives in a one-pot reaction in water at 70 °C without using any catalyst.     

Rapid synthesis of substituted 5-phenyl-1,3-dioxolan-4-ones under microwave-induced solvent-free conditions

Under microwave irradiation and without solvent, racemic and optically pure mandelic acid readily condenses with aldehydes and ketones to give 2-alkyl substituted 5-phenyl-1,3-dioxolan-4-ones in good yield.     

Convenient,multicomponent, one-pot synthesis of highly substituted pyridines under solvent-free conditions

Highly substituted pyridine derivatives have been accessed through an efficient, one-pot, multicomponent reaction of aldehydes, malononitrile, and ammonium acetate in the presence of triethylamine as a catalyst under solvent-free conditions. This procedure affords the desired products in high purity and has advantages such as short reaction time, excellent yields, and simple workup procedure. This procedure affords the desired products in moderate to high yields and has such advantages as short reaction time and simple workup procedure.     

One-pot multicomponent synthesis of polyhydroquinolines under catalyst and solvent-free conditions

Abstract

An efficient one-pot condensation has been developed for the synthesis of polyhydroquinolines via a four component coupling reaction of aldehyde, dimedone, ethyl acetoacetate, and ammonium acetate under catalyst and solvent-free conditions. Non-hazardous experiment procedure, operational simplicity, mild reaction conditions, and the compatibility with various functional groups represent the advantages of the present method.     

A green,isocyanide-based three-component reaction approach for the synthesis of multisubstituted ureas and thioureas

A one-pot, isocyanide based multicomponent protocol was presented starting from secondary amines towards (thio)urea derivatives and utilized for the construction of a diverse 27-membered chemical library. Following a green compatible microwave assisted condition, the formed N,N′-multisubstituted (thio)ureas were obtained in up to 85% yield.     

An efficient,catalyst- and solvent-free N-formylation of aromatic and aliphatic amines

Abstract

A simple, efficient, and cost-effective procedure for the synthesis of formamides under catalyst- and solvent-free conditions at 60^°C using formic acid/ethyl formate as a formylating agent has been developed. The protocol is applicable to a wide variety of aromatic and aliphatic amines providing moderate to excellent yield of desired products.     

Microwave-assisted synthesis of benzoxazinediones under solvent-free conditions

Benzoxazinediones exhibit potential as versatile synthons in the synthesis of wide variety of heterocyclic compounds with biological activity. In this work, an efficient and eco-friendly one-step synthesis of benzoxazine-2,4-diones from phthalic anhydrides derivatives and trimethylsilyl azide using the microwave technique was developed and compared with conventional heating. Microwave irradiation plays a critical role in driving the reaction and providing access to products and/or regioisomers not available from conventional heating. Thus, the regioselectivity of the reaction may be modulated by the irradiation time. Depending on the method employed the benzoxazinediones were isolated with yields in the range of 30–90%.     

Formylation of amines through catalyst- and solvent-free transamidation reaction

The transamidation between formamide and various amines proceeds under heating, without any catalyst nor solvent, providing thus green and neutral conditions for the formylation of primary and secondary amines. The resulting amide product can be directly transformed, in a one pot sequence, into monomethylamine.     

Fe3O4@SiO2@D-NHCS-Tr as an efficient and reusable catalyst for the synthesis of indol-3-yl-4H-chromene via a multi-component reaction under solvent-free conditions

Fe₃O₄@SiO₂@D-NHCS-Tr was used as an efficient catalyst in the three-component reaction between indole derivatives, salicylaldehyde, and active methylene compounds under solvent-free conditions to the synthesis of indol-3-yl-4H-chromene derivatives. The features of this method include the green conditions of the reaction, easy separation, eco-friendly and cost-effectiveness of the catalyst, and high yield in short reaction times.     

One-pot synthesis of xanthene derivatives under solvent-free conditions

One-pot synthesis of aryl-14H-dibenzo[a,j]xanthene and 1,8-dioxo-octahydroxanthene derivatives using montmorillonite K10 as reusable eco-friendly catalyst under solvent-free conditions is described.     

Efficient and green synthesis of 4H-pyrans and 4H-pyrano[2,3-c] pyrazoles catalyzed by task-specific ionic liquid [bmim]OH under solvent-free conditions

Abstract

A facile and convenient procedure for the synthesis of 4H-pyrans from aldehydes, malononitrile, and ethyl acetoacetate/acetylacetone and also synthesis of 4H-pyrano[2,3-c]pyrazoles from three-component condensation of aldehydes, malononitrile, and pyrazolone or four-component condensation of aldehydes, malononitrile, ethyl acetoacetate, and hydrazine monohydrate using [bmim]OH as task-specific ionic liquid has been described. The protocol proves to be efficient and environmentally benign in terms of high yields, low reaction times, ease of recovery, and reusability of reaction medium.

     

An efficient synthesis of quinolines under solvent-free conditions

An efficient synthesis of substituted quinolines has been achieved in a one-pot reaction from o-nitrobenzaldehyde and enolizable ketones using SnCl₂·2H₂O as the reductant under microwave irradiation without any solvent or catalyst     

Zinc perchlorate catalyzed one-pot synthesis of 3,4-dihydropyrimidinones under solvent-free conditions

Abstract

In this paper, we report zinc perchlorate hexahydrate [Zn(ClO₄)₂?6H₂O] as a highly effective catalyst for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones under solvent-free conditions. These improved reaction conditions allow the preparation of a wide variety of substituted dihydropyrimidinones in high yields and purity under mild reaction conditions. Compared with the classical Biginelli reaction, this method has the advantage of excellent yields and short reaction time in solvent-free conditions.     

A novel three-component reaction for the synthesis of 1,2-dihydroisoquinolines via the reaction of isoquinoline and isocyanides with strong CH-acids in water

A straightforward and efficient method for the synthesis of 1,2-dihydroisoquinolines via the one-pot, three-component reaction of an isocyanide, isoquinoline and a strong CH-acid in water without using any catalyst at 70 °C is reported. The method offers several advantages including high yields of products and an easy work-up procedure.     

A mild and simple synthesis of N-aryl substituted toluenesulfamides under solvent-free conditions

N- aryl substituted benzenesulfamides are often used as heating-sensitive recording material1, thermal printing material2, sensitizer3 and developer4. Moreover, some of the benzenesulfamides have antifungal activities5. Many methods have been described for preparation of sulfamides. They are used to carry out in solvent8 or in solid phase condition9. These methods required solvent or solid support and even required heating or cooling. At the same time, the process of these methods is complex. Now we have developed a new method to prepare N-aryl substituted toluenesulfamides under solvent-free conditions.In recent years, solvent-free technology has gained popularity in organic synthesis. For instance,solidstate reaction and microwave reaction have received considerable attention. Solvent-free synthesis of amides has been reported10-11. This technology has many advantages such as high efficiency and selectivity, easy separation and environmental acceptability. All these merits are in accord with green chemistry's requirements of energy-saving, high efficiency and environmental benefits.In our paper, we used a simple and efficient method for preparing N-aryl substituted toluenesulfamides under solvent-free conditions, as a replacement for classic solvent, which gives many environmental benefits.All reactions were completed at room temperature by co-grinding in an agate mortar for 3-20min and the results are shown in Table 1.In conclusion, we have developed an efficient and convenient method of preparation N-aryl substituted toluenesulfamides in high yields. It symbols an improvement for synthesis of benzenesulfamides.     

Hydroxyl ammonium ionic liquid-catalyzed simple and efficient synthesis of 5-arylidene-2,4-thiazolidinediones under solvent-free conditions

A simple and efficient synthesis of 5-arylidene-2,4-thiazolidinediones by the Knoevenagel condensation of aldehydes with 2,4-thiazolidinedione in the presence of 2-hydroxy ethylammonium propionate under solvent-free conditions is described. The attractive features of this procedure are operational simplicity, high yields, short reaction times, easy to prepare the catalyst, mild and environmentally benign reaction conditions, and recycle of the catalyst.