Morpholine triflate promoted one-pot,four-component synthesis of dihydropyrano[2,3-c] pyrazoles

A one-pot,four-component reaction of ethyl acetoacetate,hydrazine hydrate,aldehydes,and malononitrile was discussed using Lewis acid catalyst morpholine triflate (MorT) to afford a series of dihydropyrano[2,3-c] pyrazoles,which were generally catalyzed by organic alkalis.Moderate to excellent yields,no chromatographic purification,and evasion of environmentally hazardous solvents in the reaction process make this protocol very useful for academia and industry.     

Molecular sieves: an efficient and reusable catalyst for multi-component synthesis of dihydropyrano[2,3-C]pyrazole derivatives

An efficient synthesis of dihydropyrano[2,3-C]pyrazole derivatives catalyzed by molecular sieves in ethanol under reflux and ultrasound irradiation has been described. The efficiency of catalyst has been compared with other aluminates and silicate based catalyst in order to optimize catalyst for the said organic transformation. This protocol is very useful due to easy recovery of the catalyst and its reusability, short reaction time, excellent yields, and avoidance of environmentally hazardous solvents.     

H14[NaP5W30O110] catalyzed one-pot three-component synthesis of dihydropyrano[2,3-c]pyrazole and pyrano[2,3-d]pyrimidine derivatives

This is a report of an efficient, clean and facile method for the synthesis of 1,4-dihydropyrano[2,3-c] pyrazole and pyrano[2,3- d]pyrimidine derivatives via three-component one-pot condensation of 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one or barbituric acid, aldehydes and malononitrile in the presence of a catalytic amount of preyssler type heteropolyacid as a green and reusable catalyst in water or ethanol under refluxing conditions.     

Polyethylene glycol-promoted synthesis of pyrimido[1,2-a]benzimidazole and pyrano[2,3-c]pyrazole derivatives in water

Synthesis of pyrimido[1,2-a]benzimidazole and pyrano[2,3-c]pyrazole derivatives were achieved using polyethylene glycol (PEG-400) as promoting reaction medium in water under catalyst-free conditions at reflux and room temperature, respectively. The structure of pyrimido[1,2-a]benzimidazole was confirmed using ¹H NMR, ¹³C NMR, DEPT, and HMBC experiments. The promising points for the present methodology are efficiency, generality, high yield, short reaction time, cleaner reaction profile, ease of product isolation, simplicity, potential of recycling reaction medium, and finally agreement with green chemistry protocols.     

Tin sulfide nanoparticles supported on activated carbon as an efficient and reusable Lewis acid catalyst for three-component one-pot synthesis of 4H-pyrano[2,3-c]pyrazole derivatives

Tin sulfide nanoparticles (SnS‐NPs) were prepared in aqueous solution at room temperature on the surface of activated carbon (AC) and were investigated using field‐emission scanning electron mi‐croscop...     

活性炭负载硫化锡纳米颗粒作为高效可重复使用Lewis酸催化剂催化三组分一锅法合成4H-吡喃[2,3-c]吡唑衍生物(英文)

Tin sulfide nanoparticles(SnS -NPs) were prepared in aqueous solution at room temperature on the surface of activated carbon(AC) and were investigated using field-emission scanning electron mi-croscopy(FE-SEM), transmission electron microscopy(TEM), X-ray diffraction, reflective ultravio-let-visible spectrophotometry, and spectrofluorimetry. Calculations based on the SEM and TEM images showed that the sizes of the SnS -NPs immobilized on the AC were 30–70 nm. The prepared nanocomposite was used as a heterogeneous Lewis acid catalyst for the three-components one-pot synthesis of 4H-pyrano[2,3-c]pyrazole derivatives in ethanol at 80 ℃. The reactions were efficiently performed in the presence of the prepared catalyst in short reaction times, and gave the desired products in high yields. This catalyst can be easily recovered by simple filtration and recycled up to eight consecutive times without significant loss of its efficiency.     

Convenient synthesis of spiro[indoline-3,4'-pyrano[2,3-c]pyrazole] and spiro[acenaphthyl-3,4'-pyrano[2,3-c]pyrazoles] via fourcomponent reaction

The base promoted four-component reaction of hydrated hydrazine, dimethyl acetylenedicarboxylate, isatines and malononitrile (ethyl cycanoacetate) in ethanol afforded polysubstituted spiro[indoline-3,4‘-pyrano[2,3-c]pyrazoles] and spiro[acenaphthyl-3,4-pyrano[2,3-c]pyrazoles]     

Caffeine catalyzed green synthesis of novel benzo[a] [1,3]oxazino[6,5-c]phenazines via a one-pot multi-component sequential protocol in a basic ionic liquid

Caffeine was applied as a green and natural catalyst for the one-pot, four-component sequential condensation between 2-hydroxy-1,4-naphthoquinone, aromatic 1,2-diamines, ammonium thiocyanate and acid chlorides in the presence of a basic ionic liquid (1-butyl-3-methylimidazolium hydroxide) to afford the corresponding benzo[a] [1,3]oxazino[6,5-c]phenazine derivatives. In this one-pot transformation, five bonds and two new rings are efficiently formed. This protocol has the advantages of operational simplicity, high yields, easy workup, avoidance of hazardous or toxic catalysts and organic solvents and high chemo- and regioselectivities.     

CuI/La(OTf)3 catalyzed, one-pot synthesis of isomeric ellipticine derivatives in ionic liquid

An efficient method for one-pot synthesis of isomeric ellipticine derivatives through CuI/La(OTf)₃ catalyzed sequential inter/intramolecular cyclization of substituted alkynes with imines followed by aromatization is reported in good to excellent yields.     

NaF-catalyzed efficient one-pot synthesis of dihydropyrano[2,3-c]pyrazoles under ultrasonic irradiation via MCR approach

Sodium fluoride was identified as an efficient catalyst for the preparation of series of dihydropyrano [2,3-c]pyrazoles (4a–l) by the three-component condensation of 3-Methyl-1-phenyl-2-pyrazoline-5-one (1), aromatic aldehydes (2) and malononitrile (3) in aqueous methanol at ambient temperature under ultrasonication. The cost and efficacy of the catalyst, mild reaction conditions, simple workup procedure, less reaction time and higher yields of the product with analytical purity keeping this protocol superior to the previously reported ones. Structures of all the compounds were in agreement with their spectroscopic data (¹H NMR, ¹³C NMR) and elemental (CHN) analyses.     

水中3-甲基-6-氨基-5-氰基-4-芳基-1-苯基-1，4-二氢吡喃[2，3-c]吡唑的洁净合成

在水溶剂中并有三乙基苄基氯化铵（TEBA）存在下，取代芳亚甲基丙二腈与3- 甲基-1-苯基-2-吡唑啉-5-酮缩合成为3-甲基-6-氨基-5-氰基-4-芳基-1-苯基-1， 4-二氢吡喃[2,3-c]吡唑，此法为相应化合物的合成提供了一种快速、方便、高效 和洁净的方法。     

Convenient DABCO-catalyzed one-pot synthesis of multi-substituted pyrano[2,3-c]pyrazole dicarboxylates

We developed an efficient and simple one-pot synthesis of functionalized multi-substituted 2,4-dihydro-pyrano[2,3-c]pyrazole dicarboxylates from β-ketoesters, hydrazine, dimethyl acetylenedicarboxylate and malononitrile in EtOH. This four-component one-pot reaction carried out in the presence of DABCO catalyst showed advantages over a one-pot three-component method in its simple procedure, high yield and low toxicity.     

An Efficient Four-Component Synthesis of Multisubstituted Pyrano[2,3-c]pyrazole

A series of substituted pyrano[2,3-c]pyrazole derivatives were synthesized by a one-pot reaction of methyl 4-methyl-3-oxovalerate, phenylhydrazine, aromatic aldehyde, and malononitrile in ethanol with catalysis by triethylamine. The title compounds were obtained in good to excellent yields. A possible mechanism for this reaction was proposed.     

Zn(ANA)2Cl2 complex as efficient catalyst for the synthesis of dihydropyrano[2,3-c]pyrazoles in aqueous medium via one-pot multicomponent reaction: a green approach

Abstract

The first example of recyclable Zn(ANA)₂Cl₂ catalyzed tandem one-pot three-component protocol reaction between aromatic aldehydes, malononitrile, and phenylmethylpyrazolone to furnish 4-substituted-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile (4a–l) in a short reaction time (～10?min) in aqueous media at room temperature is described.     

Magnesium ferrichromate nanoparticles: an efficient and recyclable catalyst in the synthesis of pyrano[2,3-c]pyrazole derivatives

Research on Chemical Intermediates - Magnetically separable magnesium ferrichromate nanoparticles (MgFeCrO4 NPs) were synthesized by aqueous combustion synthesis (ACS) using glycine as the fuel....     

A novel synthesis of pyrazolo[3,4-b]pyridine derivatives through multi-component reaction in ionic liquid

An efficient and novel procedure for the preparation of pyrazolo[3,4-b]pyridine derivatives through multi-component reaction of aldehyde, 5-amino-3-methyl-1-phenylpyrazole and malononitrile or cyanoacetate in [bmim][BF4] is described in this paper. Advantages of the method presented here include mild conditions, high yields together with a green nature and ease of recovery and reuse of the reaction medium.     

Nonaqueous microemulsion-containing ionic liquid [bmim][PF6] as polar microenvironment

The phase behavior of toluene/Triton X-100 (TX-100)/1-butyl-3-methylimidazolium hexafluorophosphate([bmim][PF6]) was studied. It was demonstrated that the single-phase microemulsion area covered about 75% of the phase diagram at 25 °C. Electrical conductivities of the system with different w ([bmim][PF6]-to-TX-100 molar ratio) values were determined, and the results were used to locate the sub-regions of the single-phase microemulsion. The results showed that a transform from [bmim][PF6]-in-oil ([bmim][PF6]/O) microstructure via a bicontinuous region to an oil-in-[bmim][PF6] (O/[bmim][PF6]) microstructure occurred with the increase of Φ (weight fraction of TX-100 and [bmim][PF6] in the system). The aggregate size of the reverse microemulsions of [bmim][PF6]/O was determined using small-angle X-ray scattering. The results showed that the size of the reverse microemulsions depended markedly on the w values.