Nano-TiCl2/cellulose: an eco-friendly bio-based catalyst for one-pot synthesis of 4H-pyrimido[2,1-b]benzothiazole derivatives

Research on Chemical Intermediates - Cellulose is among the most abundant natural carbon-based biopolymers containing free OH groups with nucleophilic character for bonding to Lewis acids such as...     

The synthesis of some 4H-pyrimido[2,1-b]benzothiazol-4-ones

A series of 8-substituted and 7,8-disubstituted-4-oxo-3-(4H-pyrimido[2,1-b]benzothiazole)carboxylic acids and esters including a 9-aza analog were synthesized from substituted 2-aminobenzothiazoles and diethyl ethoxymethylenemalonate. The 9-aza analog, ethyl 8-methoxy-4-oxo-3-(4H-pyrido[3′,2′:4,5]thiazolo[3,2-a]pyrimidine)carboxylate ( 56 ), represents the first preparation of this new heterocyclic ring. These compounds were examined for antiparasitic activity, however, no significant activity was detected.     

Nano-[Mn-PSMP]Cl2 as a new Schiff base complex and catalyst for the synthesis of N,N'-alkylidene bisamides

Research on Chemical Intermediates - Nano-Mn-[phenyl-salicylaldimine-methyl-pyranopyrimidinedione]Cl2 {Nano-[Mn-PSMP]Cl2} as a new Schiff base complex was prepared and characterized by various...     

Preparation and characterization of nano-Co-[4-chlorophenyl-salicylaldimine-methyl pyranopyrazole]Cl2 as a new Schiff base complex and catalyst for the solvent-free synthesis of 1-amidoalkyl-2-naphthols

By the reaction of 4-chlorobenzaldehyde with ethyl acetoacetate, malononitrile, and hydrazine hydrate, 6-amino-4-(4-chlorophenyl)-3-methyl-2,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile was prepared and then reacted with salicylaldehyde and CoCl₂·6H₂O to produce nano-Co-[4-cholorophenyl-salicylaldimine-methylpyranopyrazole]Cl₂ (nano-[Co-4CSMP]Cl₂). The prepared nano-Schiff base complex was reported for the first time and fully characterized by Fourier transform-infrared spectroscopy, thermal gravimetric analysis, differential thermal gravimetric analysis, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, and Brunner–Emmett–Teller analyses and applied as an efficient catalyst for the synthesis of some 1-amidoalkyl-2-naphthol derivatives.     

A synthesis of 6,11-dihydro-2-methyl-6H-pyrimido[2,1-b]quinazolin-4-ones

Reductive cyclization of 2-methylthio-1-(2-nitrobenzyl)-6-pyrimidones with stannous chloride and acetic acid in methanol gives 6,11-dihydro-6H-pyrimido[2,1-b]quinazolin-4-ones, and, with trialkylphosphites, 6,11-dihydro-11-alkylpyrimido[2,1-b]quinazolin-4-ones.     

Nicotine-based ionic liquid supported on magnetic nanoparticles: An efficient and recyclable catalyst for selective one-pot synthesis of mono- and bis-4H-pyrimido[2,1-b]benzothiazoles

In this study, an acidic nicotine-based ionic liquid supported on magnetic nanoparticles ([NicTC]HSO₄@MNPs) was synthesized and characterized by different techniques. The activity of this catalyst was evaluated in a multi-component reaction of 2-aminobenzothiazole , aldehydes / dialdehydes and β-ketoesters/1,3-diketones to afford a series of novel mono- and bis-4H-pyrimido[2,1-b]benzothiazole derivatives. In addition, mild reaction conditions, high yields, excellent selectivity as well as easy recovery and reusability of the catalyst, make this method an economic and environmentally-benign process.     

Synthesis of pyranopyrazoles using nano‐Fe‐[phenylsalicylaldiminemethylpyranopyrazole]Cl2 as a new Schiff base complex and catalyst

By the condensation reaction of benzaldehyde with ethyl acetoacetate, malononitrile and hydrazine hydrate in the presence of FeCl₂, a pyranopyrazole derivative was prepared which was then reacted with salicylaldehyde to afford nano‐Fe‐[phenylsalicylaldiminemethylpyranopyrazole]Cl₂ (nano‐[Fe‐PSMP]Cl₂). The prepared nano‐Schiff base complex was fully characterized using Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, differential thermogravimetry, scanning electron microscopy and UV–visible spectroscopy, and was used as an efficient and catalyst for the preparation of pyranopyrazoles.     

Caffeine-H2SO4: a novel dual acidic catalyst for one-pot preparation of 2H-indazolo[2,1-b]phthalazinetriones

Research on Chemical Intermediates - Caffeine-H2SO4 was prepared as a novel dual acidic catalyst. The catalytic activity of caffeine-H2SO4 was evaluated in one-pot preparation of...     

Efficient polymeric catalyst for one-pot synthesis of acenaphtho[1,2-b]pyrroles

Some new derivatives of acenaphtho[1,2-b]furans have been synthesized efficiently by one-pot reaction of (acenaphthylen-1-yloxy)trimethylsilane, various aldehydes, and isocyanides in the presence of silica-supported ionic liquid.     

Nano‐Zn[2‐boromophenylsalicylaldiminemethylpyranopyrazole]Cl2 as a novel nanostructured Schiff base complex and catalyst for the synthesis of pyrano[2,3‐d]pyrimidinedione derivatives

Nano‐Zn[2‐boromophenylsalicylaldiminemethylpyranopyrazole]Cl₂ (nano‐[Zn‐2BSMP]Cl₂) as a novel nanostructured Schiff base complex was prepared and characterized using several techniques. Nano‐[Zn‐2BSMP]Cl₂ was used as an effective catalyst for the preparation of some pyrano[2,3‐d]pyrimidinedione derivatives by the multicomponent reaction of malononitrile, aryl aldehydes and barbituric acid derivatives. The novelty and efficiency of nano‐[Zn‐2BSMP]Cl₂ as a catalyst, in comparison with some other reported catalysts, for this synthetic transformation are the main features of this work.     

Three-component synthesis of 4-amino-2-aryl-2H-pyrimido-[1,2-b][1,3]benzazole-3-carbonitriles and 4H-pyrimido-[2,1-b][1,3]benzazoles in the presence of magnesium oxide and 12-tungstophosphoric acid as catalysts

A simple and convenient approach was suggested for the synthesis of 4-amino-2-aryl-2H-pyrimido[1,2-b][1,3]benzimidazole-3-carbonitriles or -benzothiazole-3-carbonitriles through a three-component reaction of 2-aminobenzimidazole or 2-aminobenzothiazole, aldehyde, and malononitrile in the presence of magnesium oxide (MgO) and 12-tungstophosphoric acid as catalysts. Three-component reactions of aldehyde, β-ketoester, and 2-aminobenzimidazole or 2-aminobenzothiazole with the formation of 4H-pyrimido[2,1-b]benzimidazole or 4H-py-rimido[2,1-b]benzothiazole derivatives, respectively, were also studied. These approaches have the advantage of high yields, rapid and pure course of the reactions, as well as the use of cheap and available catalysts.     

A facile copper-catalyzed one-pot domino synthesis of 5,12-dihydroindolo[2,1-b]quinazolines

A domino synthesis of 5,12-dihydroindolo[2,1-b]quinazoline derivatives via copper-catalyzed Ullmann-type intermolecular C-C and intramolecular C-N couplings is reported. Good yields of various 5,12-dihydroindolo[2,1-b]quinazoline derivatives were obtained. Reaction scopes, limitations, and the reaction mechanism are discussed.     

A new and facile synthesis of imidazo[2,1-b]oxazoles

An efficient and clean two step procedure for the synthesis of imidazo[2,1-b]oxazoles has been developed from 2-aminooxazoles using titanium(IV) chloride assisted cyclization, and a variety of imidazo[2,1-b]oxazoles have been synthesized in good yields. The structure of one of the products was confirmed by X-ray crystallographic analysis.     

A new vanadium Schiff base complex as catalyst for oxidation of alcohols

The monoanionic bidentate Schiff base, N-(phenolyl)-benzaldimine (HL), has been employed to synthesize a new vanadium(IV) complex of general composition [VO(L)₂] (where L?=?O,?N donor of Schiff base). The ligand and complex have been fully characterized by elemental analyses, molar conductance data, FT-IR, ¹H- and ¹³C-NMR, and UV-Vis spectroscopies. Oxidation of alcohols to their corresponding aldehydes and ketones was conducted by this complex catalyst using Oxone as oxidant under biphasic reaction conditions (CH₂Cl₂/H₂O) and tetra-n-butylammonium bromide as phase transfer agent under air at room temperature.     

β-Cyclodextrin as a supramolecular catalyst for the synthesis of 2Hindazolo[2,1-b]phthalazine-trione derivatives in water and their antimicrobial activities

An efficient and green method has been developed for the synthesis of 2H-indazolo[2,1-b]phthalazinetriones derivatives by employing 15 mol%β-cyclodextrinvia a one-pot multicomponent reaction of aldehyde,dimedone,hydrazine hydrate with succinic anhydride/phthalic anhydride in water at 80 ℃ for first time.The catalyst could be recovered and reused for four consecutive cycles without appreciable loss in catalytic activity and evaluated for in vitro antimicrobial activity against different Gram-positive and Gram-negative bacterial strains.The outcome of the screening study showed that compound 6d,6f and7 n exhibited excellent activity against E.coil.Whereas,compound 6f and 6h exhibited excellent activity against P.aeurginosa,and compound 6c,and 6e displayed again excellent activity against Staphylococcus aureus whereas compound 7o shows excellent activity against S.aureus and B.subtilis when compared with Ampicillin(standard control).The results indicated that maximum compounds are moderately effective against bacterial growth and their effectiveness is highest against standard drugs.     

Polymeric catalyst for the synthesis of new pyrido[2,3-b]indoles

A new and efficient method has been developed for the one-pot synthesis of novel 2,9-dihydro-2-oxo-4-aryl-1H-pyrido[2,3-b]indole-3-carbonitrile derivatives by condensation of substituted (triethoxymethyl)arene, 1-methyl-1H-indol-2-ol and cyanoacetamide in the presence of a catalytic amount of crosslinked poly(2-acrylamido-2-methyl propane sulfonic acid) (AMPS) as an efficient and heterogeneous catalyst. This polymeric solid acid catalyst is stable and can be easily recovered and reused without significant change in its activity.     

Synthesis of 3a,6,6,9a-tetramethyl-trans-perhydronaphtho [2,1-b]furan and 4a,7,7,10a-tetramethyl-trans-perhydronaphtho [2,1-b]pyran

The compounds 3a,6,6,9a-tetramethyl-trans-perhydronaphtho[2,1-b]furan (ambrox or ambroxide) and 4a,7,7,10a-tetramethyl-trans-perhydronaphtho[2,1-b]pyran (homofixator) — substances important in the perfume industry — have been synthesized by superacid cyclization of E,E-homofarnesol and E,E-bishomofarnesol or mixtures of the isomeric bicyclohomofarnesenes or bicyclobishomofarnesenols. Superacid cyclization of these alcohols was shown to be an effective structurally selective and stereospecific method of obtaining ambroxide and homofixator.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 896–901, July, 1990.     

Nano–Mn‐[4‐nitrophenyl‐salicylaldimine‐methyl pyranopyrazole]Cl2 as a new nanostructured Schiff base complex and catalyst for the synthesis of hexahydroquinolines

By the reaction of 4‐nitrobenzaldehyde with ethyl acetoacetate, malononitrile and hydrazine hydrate, pyranopyrazole derivative as an active biological compound was synthsized and then reacted with salicylaldehyde and MnCl₂.4H₂O to afford nano‐Mn‐[4‐nitrophenyl‐salicylaldimine‐methyl pyranopyrazole]Cl₂ (nano‐[Mn‐4NSMP]Cl₂) for the first time. The produced Schiff base complex with nanostructured was fully characterized by Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), thermal gravimetric analysis (TGA), differential thermal gravimetric (DTG) and scanning electron microscope (SEM) and used it as an efficient catalyst for the preparation of hexahydroquinolines.