Aqua one-pot,three-component synthesis of dihydropyrano[3,2-c]chromenes and amino-benzochromenes catalyzed by sodium malonate

Research on Chemical Intermediates - The widespread biological properties of dihydropyrano[3,2-c]chromenes, 2-amino-4-aryl-4H-benzo[h]chromenes, and 3-amino-1-aryl-1H-benzo[f]chromenes have led to...     

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.     

Ni(II)-Schiff base/SBA-15: a nanostructure and reusable catalyst for one-pot three-component green synthesis of 3,4-dihydropyrano[3,2-c]chromene derivatives

Research on Chemical Intermediates - An efficient, rapid, and environmentally benign Ni(II)-Schiff base/SBA-15-catalyzed one-pot three-component cyclocondensation process was described via the...     

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.

     

One-pot synthesis of multisubstituted imidazoles catalyzed by Dendrimer-PWA<Superscript>n</Superscript> nanoparticles under solvent-free conditions and ultrasonic irradiation

An efficient, green and eco-friendly protocol has been developed for the synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles via one-pot condensation reaction using Dendrimer-PWAⁿ as catalyst under solvent-free conditions or ultrasonic irradiation in excellent yields. The reactions under conventional heating conditions were compared with the ultrasonic-assisted reactions. The operational simplicity, practicability and applicability of this protocol to various substrates make it an interesting alternative to previous procedures. The present methodology offers several advantages such as excellent yields, short reaction times, a cleaner reaction, and the absence of any tedious work-up or purification. The catalyst is easily separated from the products by filtration and also exhibits remarkable reusable activity. SEM, BET and DLS of the catalyst were also investigated after each reaction cycle.     

Self-sorting under solvent-free conditions: one-pot synthesis of a hetero[3]rotaxane

The one-pot synthesis of a hetero[3]rotaxane, assembled from five different molecular components under solvent-free conditions, through "self-sorting" of the bead and stopper units during the threading and stoppering processes, is reported.     

B(C6F5)3 catalyzed synthesis of dihydropyrano[3,2-b]chromenediones under solvent-free conditions

Abstract

A simple, efficient, solventless, and one step, B(C₆F₅)₃ catalyzed, synthesis of dihydropyrano[3,2-b]chromenediones from dimedone, aldehyde and kojic acid is described. This protocol proceeds smoothly, accommodates aromatic as well as heteroaromatic aldehydes and gives dihydropyrano[3,2-b]chromenediones in excellent yield.     

Cobalt-based nanocatalyst catalyzed one-pot four-component synthesis 2<Emphasis Type="Italic">H</Emphasis>-indazolo[2,1-b]phthalazine-triones under solvent-free condition

In this research, an efficient procedure for the one-pot four-component synthesis of 2H-indazolo[2,1-b]phthalazine-triones catalyzed by a cobalt-based nanocatalyst (Co/Al₂O₃ nanocatalyst) is reported. The catalyst was prepared by a co-precipitation method and characterized by BET surface area, SEM, TEM, EDS and XRD analyses. A wide range of various aromatic aldehydes including electron-withdrawing and electron-releasing groups were applied and corresponding products obtained in high yields without any by-product. Moreover, the Co/Al₂O₃ is recyclable up to 7 consecutive runs by simple filtration.     

CAN-catalyzed synthesis of 10-arylpyrano[3,2-b]chromene-4,9-diones under solvent-free conditions

A novel and efficient one-pot synthesis of 10-aryl-7,8-dihydropyrano[3,2-b]chromene-4,9(6H,10H)-diones by three-component reaction of aromatic aldehydes, 5-hydroxy-2-methylpyran-4-one, and cyclic 1,3-dicarbonyl compounds in the presence of a catalytic amount of ceric ammonium nitrate under solvent-free conditions is described. The advantages of this method include operational simplicity, short reaction time, recyclable catalyst, and high yields.     

Microwave-assisted novel synthesis of amino-thieno[3,2-b]pyridines under solvent-free conditions

In the presence of a catalytic amount of ytterbium(III) triflate and under microwave irradiation, mixtures of 2-amino-3-thiophenecarbonitriles, ketones, and silica gel afforded smoothly the corresponding amino-thieno[2,3-b]pyridine derivatives in one step. A wide variety of ketones were tested under these conditions. The reactions proceeded rapidly and afforded the desired products in good to excellent yields.     

Efficient one-pot synthesis of 14-substituted-14H-dibenzo[a,j]xanthenes using boric acid under solvent-free conditions

<正>Boric acid efficiently catalysed the one-pot reaction of alkyl or aryl aldehydes with 2-naphthol to afford the corresponding 14- alkyl-or aryl-14H-dibenzo[a,j]xanthenes in good yields under solvent-free conditions.     

Cross reactions of cyanoacetic acid derivatives with carbonyl compounds 3. One-step synthesis of substituted 2-amino-5-oxo-4,5-dihydropyrano[3,2-c]chromenes

Three-component reactions of 4-hydroxycoumarin, carbonyl compounds, and malono-nitrile or alkyl cyanoacetates in ethanol in the presence of Et₃N as a catalyst give substituted 2-amino-5-oxo-4,5-dihydropyrano[3,2-c]chromenes. Dedicated to Academician V. I. Minkin on the occasion of his 70th birthday. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 968–972, April, 2005.     

α-Fe_2O_3 nanoparticles:An efficient,inexpensive catalyst for the one-pot preparation of 3,4-dihydropyrano[c]chromenes

This paper describes the combustion synthesis ofα-Fe₂O₃ nanopowder at much lower temperature and its catalytic activity for the one-pot preparation of 3,4-dihydropyrano[c]chromenes.The combustion derivedα-Fe₂O₃ nanopowder was characterized by powder X-ray diffraction（PXRD）,Braunauer,Emmett and Teller（BET） surface area,scanning electron microscopy（SEM） and Fourier transform infrared spectroscopy（FTIR）.Highly efficient,three-component condensation of aromatic aldehyde,malanonitrile and 4- hydroxycoumarin catalyzed byα-Fe₂O₃ nanoparticles at room temperature is described.The method offers an excellent alternative to the synthesis of 3,4-dihydropyrano[c]chromenes.The reactions are rapid,clean,and the products with good yield and high purity.     

Theoretical prediction on vibrational spectra of [Ar...Ar-H]<Superscript>+</Superscript>

Centrosymmetric linear [Ar-H-Ar]⁺ and asymmetric linear [Ar---Ar-H]⁺ are two stable configurations of [Ar₂H]⁺. Based on the global potential energy surface of [Ar₂H]⁺ provided by our group recently, we calculated the vibrational spectra of [Ar---Ar-H]⁺ with total angular momentum J = 0 by time-dependent quantum mechanical method, and the influence of quantum tunneling effect on vibrational spectra was found. With the help of the observation on the eigenstate functions and the modified potential energy surface, assignments were made to the spectra. The strong coupling between the excited bending mode of [Ar-H-Ar]⁺ and the vibrational states of [Ar---Ar-H]⁺ was discussed.     

Regioselective synthesis of fused benzopyrazolo[3,4-b]quinolines under solvent-free conditions

New 6,8-dihydro-5H-benzo[f]pyrazolo[3,4-b]quinolines 6 have been obtained in a novel solvent-free three-component reaction involving β-tetralone along with 5-aminopyrazoles 1 and benzaldehydes 2. The isomeric 6,10-dihydro-5H-benzo[h]pyrazolo[3,4-b]quinolines 9 could not be prepared in a similar fashion directly from α-tetralone, but were obtained by the reaction of amines 1 with benzylidene-derivative 10 of α-tetralone in similar conditions. The yields of quinolines obtained via this novel protocol were good and the reaction times varied from few minutes to just few seconds.     

Theophylline as a new and green catalyst for the one-pot synthesis of spiro[benzo[a]pyrano[2,3-c]phenazine] and benzo[a]pyrano[2,3-c]phenazine derivatives under solvent-free conditions

A green, convenient, high yielding and one-pot procedure for the synthesis of novel spiro[benzo[a]pyrano[2,3-c]phenazine] derivatives by domino multi-component condensation reaction between 2-hydroxynaphthalene-1,4-dione, benzene-1,2-diamines, ninhydrine, and malononitrile in the presence of a catalytic amount of 1,3-dimethyl-7H-purine-2,6-dione (theophylline) as an expedient, eco-friendly and reusable solid base catalyst under thermal, microwave irradiation and solvent-free conditions. This procedure has also been applied successfully for the synthesis of benzo[a]pyrano[2,3-c]phenazines.     

A concise synthesis of furo[3,2-c]coumarins catalyzed by nanocrystalline ZnZr<Subscript>4</Subscript>(PO<Subscript>4</Subscript>)<Subscript>6</Subscript> ceramics under microwave irradiation

A simple and concise method catalyzed by nanocrystalline ZnZr₄(PO₄)₆ ceramics has been reported for the synthesis of a series of trans-2-benzoyl-3-(aryl)-2H-furo[3,2-c]chromen-4(3H)-ones using a multicomponent reaction of 2,4′-dibromoacetophenone, benzaldehydes and 4-hydroxycoumarin under microwave irradiation. This method provides several advantages including easy workup, excellent yields, short reaction times, using of microwave as clean method, recoverability of the catalyst and little catalyst loading.     

DBU: a highly efficient catalyst for one-pot synthesis of substituted 3,4-dihydropyrano[3,2-c]chromenes, dihydropyrano[4,3-b]pyranes, 2-amino-4H-benzo[h]chromenes and 2-amino-4H benzo[g]chromenes in aqueous medium

We have reported DBU catalyzed one-pot synthesis of 3,4-dihydropyrano[3,2-c]chromenes, dihydropyrano[4,3-b]pyranes, 2-amino-4H-benzo[h]chromenes and 2-amino-4H-benzo[g]chromenes from aldehydes, active methylene compounds malononitrile/ethyl cyanocacetate, and 4-hydroxycoumarin/4-hydroxy-6-methylpyrone/1-naphthol/2-hydroxynaphthalene-1,4-dione in water under reflux. The attractive features of this process are mild reaction conditions, reusability of the reaction media, short reaction times, easy isolation of products, and excellent yields.