scholarly journals Heteropoly Acid Catalyzed Selective Cyclization of 6-Alkyl-3-propargylmercapto-1,2,4-triazin-5(2H)-one

2011 ◽  
Vol 8 (2) ◽  
pp. 798-802 ◽  
Author(s):  
Fatemeh Hakim ◽  
Masoumeh Tabatabaee ◽  
Majid M. Hheravi ◽  
Mina Roshani ◽  
Fatemeh F. Bamoharam
Keyword(s):  
Heteropoly Acid ◽  
Reaction Times ◽  
Keggin Structure ◽  
Heteropoly Acids ◽  
Acid Catalyzed ◽  
High Yields

Cyclization of 6-alkyl-3-propargylmercapto-1,2,4-triazin-5(2H)-one, derivatives (2) in the presence of Keggin heteropoly acids, H3PW1212O40, H3PMo12O40, H4SiW12O40and lacunary Keggin structure (K7PMo2W9O40) afforded 3 (3a = 6-dimethyl-7H-thiazolo[2,3-b][1,2,4]-triazin-7-one and 3b=6-ethyl-3-methyl-7H-thiazolo[2,3-b][1,2,4]-triazin-7-one) in high yields and short reaction times

scholarly journals One-Pot Synthesis of Tetrasubstituted Imidazoles Catalyzed by Preyssler-Type Heteropoly Acid

2011 ◽  
Vol 8 (2) ◽  
pp. 547-552 ◽  
Author(s):  
Ali Javid ◽  
Majid M. Heravi ◽  
F. F. Bamoharram ◽  
Mohsen Nikpour
Keyword(s):  
Heteropoly Acid ◽  
Ammonium Acetate ◽  
Reaction Times ◽  
Acid Catalyst ◽  
Aromatic Aldehydes ◽  
Primary Amines ◽  
One Pot ◽  
High Yields ◽  
Work Up ◽  
Tetrasubstituted Imidazoles

A simple one-pot four-component synthetic method was reported for the preparation of tetrasubstituted imidazole derivatives from benzil, aromatic aldehydes, primary amines and ammonium acetate in the presence of Preyssler-type heteropoly acid catalyst. This method was proved to be eco-benign, easy work-up, convenient, relatively short reaction times and the products were isolated with high yields.

Hafnium(IV) Chloride Catalyzes Highly Efficient Acetalization of Carbonyl Compounds

2019 ◽  
Vol 16 (6) ◽  
pp. 913-920 ◽  
Author(s):  
Israel Bonilla-Landa ◽  
Emizael López-Hernández ◽  
Felipe Barrera-Méndez ◽  
Nadia C. Salas ◽  
José L. Olivares-Romero
Keyword(s):  
Microwave Heating ◽  
Reaction Times ◽  
Protecting Groups ◽  
Catalyst Loading ◽  
Selective Protection ◽  
Highly Efficient ◽  
Aldehydes And Ketones ◽  
High Yields ◽  
Novel Catalyst ◽  
Acid Labile

Background: Hafnium(IV) tetrachloride efficiently catalyzes the protection of a variety of aldehydes and ketones, including benzophenone, acetophenone, and cyclohexanone, to the corresponding dimethyl acetals and 1,3-dioxolanes, under microwave heating. Substrates possessing acid-labile protecting groups (TBDPS and Boc) chemoselectively generated the corresponding acetal/ketal in excellent yields. Aim and Objective: In this study. the selective protection of aldehydes and ketones using a Hafnium(IV) chloride, which is a novel catalyst, under microwave heating was observed. Hence, it is imperative to find suitable conditions to promote the protection reaction in high yields and short reaction times. This study was undertaken not only to find a novel catalyst but also to perform the reaction with substrates bearing acid-labile protecting groups, and study the more challenging ketones as benzophenone. Materials and Methods: Using a microwave synthesis reactor Monowave 400 of Anton Paar, the protection reaction was performed on a raging temperature of 100°C ±1, a pressure of 2.9 bar, and an electric power of 50 W. More than 40 substrates have been screened and protected, not only the aldehydes were protected in high yields but also the more challenging ketones such as benzophenone were protected. All the products were purified by simple flash column chromatography, using silica gel and hexanes/ethyl acetate (90:10) as eluents. Finally, the protected substrates were characterized by NMR 1H, 13C and APCI-HRMS-QTOF. Results: Preliminary screening allowed us to find that 5 mol % of the catalyst is enough to furnish the protected aldehyde or ketone in up to 99% yield. Also it was found that substrates with a variety of substitutions on the aromatic ring (aldehyde or ketone), that include electron-withdrawing and electrondonating group, can be protected using this methodology in high yields. The more challenging cyclic ketones were also protected in up to 86% yield. It was found that trimethyl orthoformate is a very good additive to obtain the protected acetophenone. Finally, the protection of aldehydes with sensitive functional groups was performed. Indeed, it was found that substrates bearing acid labile groups such as Boc and TBDPS, chemoselectively generated the corresponding acetal/ketal compound while keeping the protective groups intact in up to 73% yield. Conclusion: Hafnium(IV) chloride as a catalyst provides a simple, highly efficient, and general chemoselective methodology for the protection of a variety of structurally diverse aldehydes and ketones. The major advantages offered by this method are: high yields, low catalyst loading, air-stability, and non-toxicity.

A highly efficient and green approach for the synthesis of pyrimido[4,5-b]quinolines using N,N-diethyl-N-sulfoethanaminium chloride

2021 ◽  
Vol 76 (2) ◽  
pp. 85-90
Author(s):  
Abdolkarim Zare ◽  
Manije Dianat
Keyword(s):  
Reaction Times ◽  
Solvent Free ◽  
One Pot ◽  
Catalyst Amount ◽  
Green Protocol ◽  
Highly Efficient ◽  
Green Approach ◽  
Solvent Free Conditions ◽  
The One ◽  
High Yields

Abstract A highly efficient and green protocol for the synthesis of pyrimido[4,5-b]quinolines has been described. The one-pot multicomponent reaction of dimedone with arylaldehydes and 6-amino-1,3-dimethyluracil in the presence of N,N-diethyl-N-sulfoethanaminium chloride ([Et3N–SO3H][Cl]) as an ionic liquid (IL) catalyst under solvent-free conditions afforded the mentioned compounds in high yields and short reaction times. Our protocol is superior to many of the reported protocols in terms of two or more of these factors: the reaction times, yields, conditions (solvent-free versus usage of organic solvents), temperature and catalyst amount.

Ultrasound-assisted aqua-mediated synthesis of multi-substituted tetrahydropyridine-3-carboxylates using N-carboxymethyl-3-pyridinium hydrogensulfate ([N-CH2CO2H-3-pic]+HSO4−) as a new efficient ionic liquid catalyst

2021 ◽  
Vol 3 (6) ◽  
Author(s):  
Kobra Nikoofar ◽  
Fatemeh Shahriyari
Keyword(s):  
Ionic Liquid ◽  
Reaction Times ◽  
Aromatic Aldehydes ◽  
Environmentally Benign ◽  
H Nmr ◽  
Sonic Waves ◽  
Ft Ir ◽  
High Yields ◽  
Work Up ◽  
C Nmr

AbstractA simple, straightforward, and ultrasound-promoted method for the preparation of some highly functionalized tetrahydropyridines reported via pseudo five-component reaction of (hetero)aromatic aldehydes, different anilines, and alkyl acetoacetates in the presence of [N-CH2CO2H-3-pic]+HSO4−, as a novel ionic liquid, in green aqueous medium. The IL was synthesized utilizing simple and easily-handled substrates and characterized by FT-IR, 1H NMR, 13C NMR, GC-MASS, FESEM, EDX, and TGA/DTG techniques. The procedure contains some highlighted aspects which are: (a) performing the MCR in the presence of aqua and sonic waves, as two main important and environmentally benign indexes in green and economic chemistry, (b) high yields of products within short reaction times, (c) convenient work-up procedure, (d) preparing the new IL via simple substrates and procedure.

scholarly journals Rapid four-component synthesis of dihydropyrano[2,3-c]pyrazoles using nano-eggshell/Ti(IV) as a highly compatible natural based catalyst

BMC Chemistry ◽  
2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Arefeh Dehghani Tafti ◽  
Bi Bi Fatemeh Mirjalili ◽  
Abdolhamid Bamoniri ◽  
Naeimeh Salehi
Keyword(s):  
Thermo Gravimetric Analysis ◽  
Reaction Times ◽  
Diffraction Field ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Solvent Free Conditions ◽  
High Yields ◽  
Work Up

AbstractNano-eggshell/Ti(IV) as a novel naturally based catalyst was prepared, characterized and applied for the synthesis of dihydropyrano[2,3-c]pyrazole derivatives. The characterization of nano-eggshell/Ti(IV) was performed using Fourier Transform Infrared spectroscopy, X-ray Diffraction, Field Emission Scanning Electron Microscopy, Energy-Dispersive X-ray Spectroscopy, and Thermo Gravimetric Analysis. Dihydropyrano[2,3-c]pyrazoles were synthesized in the presence of nano-eggshell/Ti(IV) via a four component reaction of aldehydes, ethyl acetoacetate, malononitrile and hydrazine hydrate at room temperature under solvent free conditions. The principal affairs of this procedure are mild condition, short reaction times, easy work-up, high yields, reusability of the catalyst and the absence of toxic organic solvents.

Heteropoly acid-catalyzed three-component aza-Diels–Alder reaction in a continuous micro-flow system

RSC Advances ◽  
2015 ◽  
Vol 5 (72) ◽  
pp. 58798-58803 ◽  
Author(s):  
Wei He ◽  
Zheng Fang ◽  
Zhao Yang ◽  
Dong Ji ◽  
Kai Guo
Keyword(s):  
Water Absorption ◽  
Heteropoly Acid ◽  
Phosphotungstic Acid ◽  
Flow System ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction ◽  
System P ◽  
Micro Flow ◽  
Acid Catalyzed

The first direct aza-Diels–Alder reaction catalyzed using phosphotungstic acid combined with a water absorption device in a micro-flow system was reported.

Rapid and Green One-Pot Synthesis of Novel 2-(4-Hydroxy-2-oxo-2H-chromen-3-yl)-2-(arylamino)-1H-indene-1,3(2H)-diones

2021 ◽  
Vol 18 ◽  
Author(s):  
Abolfazl Olyaei ◽  
Zahra Ghahremany ◽  
Madieh Sadeghpour
Keyword(s):  
Aromatic Amines ◽  
Low Cost ◽  
Guanidine Hydrochloride ◽  
Reaction Times ◽  
Solvent Free ◽  
One Pot ◽  
Solvent Free Conditions ◽  
The One ◽  
High Yields ◽  
Work Up

: A green and efficient protocol was developed for the one-pot three-component synthesis of novel 2-(4-hydroxy-2-oxo-2H-chromen-3-yl)-2-(arylamino)-1H-indene-1,3(2H)-dione derivatives by the reaction of 4-hydroxycoumarin, ninhydrin and aromatic amines in the presence of guanidine hydrochloride as an organocatalyst under solvent-free conditions. The present approach offers several advantages such as low cost, simple work-up, short reaction times, chromatography-free purification, high yields and greener conditions.

Heteropoly acid-catalyzed aza-Prins-cyclization: an expeditious synthesis of 4-hydroxypiperidines

2009 ◽  
Vol 50 (16) ◽  
pp. 1799-1802 ◽  
Author(s):  
J.S. Yadav ◽  
B.V. Subba Reddy ◽  
D.N. Chaya ◽  
G.G.K.S. Narayana Kumar ◽  
P. Naresh ◽  
...  
Keyword(s):  
Heteropoly Acid ◽  
Prins Cyclization ◽  
Acid Catalyzed
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