scholarly journals Microwave-assisted cyclizations promoted by polyphosphoric acid esters: a general method for 1-aryl-2-iminoazacycloalkanes

2016 ◽  
Vol 12 ◽  
pp. 2026-2031 ◽  
Author(s):  
Jimena E Díaz ◽  
María C Mollo ◽  
Liliana R Orelli
Keyword(s):  
Polyphosphoric Acid ◽  
General Procedure ◽  
Reaction Times ◽  
Ring Closure ◽  
Heterocyclic Synthesis ◽  
Microwave Assisted ◽  
Solvent Free Conditions ◽  
High Yields ◽  
Acid Esters ◽  
General Method

The first general procedure for the synthesis of 5 to 7-membered 1-aryl-2-iminoazacycloalkanes is presented, by microwave-assisted ring closure of ω-arylaminonitriles promoted by polyphosphoric acid (PPA) esters. 1-Aryl-2-iminopyrrolidines were easily prepared from the acyclic precursors employing a chloroformic solution of ethyl polyphosphate (PPE). The use of trimethylsilyl polyphosphate (PPSE) in solvent-free conditions allowed for the synthesis of 1-aryl-2-iminopiperidines and hitherto unreported 1-aryl-2-iminoazepanes. The cyclization reaction involves good to high yields and short reaction times, and represents a novel application of PPA esters in heterocyclic synthesis.

scholarly journals Microwave-assisted synthesis of 2-substituted 4,5,6,7-tetrahydro-1,3-thiazepines from 4-aminobutanol

2020 ◽  
Vol 16 ◽  
pp. 32-38
Author(s):  
María C Mollo ◽  
Natalia B Kilimciler ◽  
Juan A Bisceglia ◽  
Liliana R Orelli
Keyword(s):  
General Procedure ◽  
Reaction Times ◽  
Solvent Free ◽  
Ring Closure ◽  
Microwave Assisted Synthesis ◽  
Microwave Assisted ◽  
Solvent Free Conditions

A general procedure for the synthesis of 2-substituted tetrahydro-1,3-thiazepines by MW-assisted cyclization of 4-thioamidobutanols is presented. The acyclic precursors were prepared in high overall yields by an expeditious three-step diacylation/thionation/deprotection sequence from 4-aminobutanol. Microwave-assisted ring closure of 4-thioamido alcohols promoted by trimethylsilyl polyphosphate (PPSE) in solvent-free conditions allowed for the synthesis of several hitherto unreported seven-membered iminothioethers bearing 2-aryl, alkenyl, aralkyl and alkyl substituents. The cyclodehydration reaction is likely to involve an SN2-type displacement and affords good to excellent yields of the desired heterocycles in very short reaction times.

scholarly journals Microwave-assisted Synthesis of 2-Substituted 4,5,6,7-Tetrahydro-1,3-thiazepines from 4-Aminobutanol

2019 ◽  
Author(s):  
María C Mollo ◽  
Natalia B Kilimciler ◽  
Juan A Bisceglia ◽  
Liliana R Orelli
Keyword(s):  
General Procedure ◽  
Reaction Times ◽  
Solvent Free ◽  
Ring Closure ◽  
Microwave Assisted Synthesis ◽  
Microwave Assisted ◽  
Solvent Free Conditions

A general procedure for the synthesis of 2-substituted tetrahydro-1,3-thiazepines is presented, by MW-assisted cyclization of 4-thioamidobutanols. The acyclic precursors were prepared in high overall yields by an expeditious three step diacylation/thionation/deprotection sequence from 4-aminobutanol. Microwave assisted ring closure of 4-thioamidoalcohols promoted by trimethylsilyl polyphosphate (PPSE) in solvent-free conditions allowed for the synthesis of several hitherto unreported seven-membered iminothioethers bearing 2-aryl, alkenyl, aralkyl and alkyl substituents. The cyclodehydration reaction is likely to involve a SN2-type displacement and affords good to excellent yields of the desired heterocycles in very short reaction times.

Microwave-Assisted Synthesis of 2-Substituted 2-Thiazolines and 5,6-Dihydro-4H-1,3-thiazines

Synthesis ◽  
2020 ◽  
Vol 52 (11) ◽  
pp. 1666-1679
Author(s):  
Liliana R. Orelli ◽  
María C. Mollo ◽  
Juan A. Bisceglia ◽  
Natalia B. Kilimciler ◽  
Michele Mancinelli
Keyword(s):  
Reaction Times ◽  
Ring Closure ◽  
Cyclization Reaction ◽  
Microwave Assisted Synthesis ◽  
Metal Free ◽  
Microwave Assisted ◽  
Whole Process ◽  
High Yields ◽  
General Method

An efficient and general method for the synthesis of 2-substituted thiazolines and 5,6-dihydro-4H-1,3-thiazines is developed via microwave-assisted ring closure of ω-thioamidoalcohols promoted by ethyl polyphosphate (PPE). The cyclization reaction involves an SN2-type mechanism and features the advantages of very short reaction times, high yields and a predictable stereochemical outcome. The acyclic precursors are prepared in high overall yields by an improved diacylation–thionation–saponification sequence from commercially available ω-amino­alcohols. The whole process is metal-free and operationally simple.

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.

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.

Solid-state regioselective nitration of activated hydroxyaromatics and hydroxycoumarins with cerium (IV) ammonium nitrate

2005 ◽  
Vol 2005 (11) ◽  
pp. 733-735 ◽  
Author(s):  
Nemai C. Ganguly ◽  
Sanjoy Dutta ◽  
Mrityunjoy Datta ◽  
Prithwiraj De
Keyword(s):  
Solid State ◽  
Ammonium Nitrate ◽  
High Efficiency ◽  
Solvent Free ◽  
High Melting ◽  
Microwave Assisted ◽  
Solvent Free Conditions ◽  
High Yields ◽  
Regioselective Nitration ◽  
Cerium Iv Ammonium Nitrate

Predominant ortho-selective mononitration of low-melting and liquid phenols and hydroxycoumarins in moderate to high yields has been accomplished upon grinding with solid cerium (IV) ammonium nitrate (CAN). Microwave-assisted expeditious CAN-mediated nitration of relatively high melting phenols and hydroxycoumarins with high efficiency and selectively under solvent-free conditions has been also developed to address the problems of sluggishness and low yield for these reluctant substrates.

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.

scholarly journals Silica Supported Acids (SiO2-HClO4, SiO2-KHSO4) as Eco-friendly Reusable Catalysts for Bromination of Aromatic and Heteroaromatic Compoundsusing Kbr Under Solvothermal and Solvent-free Conditions

2021 ◽  
Author(s):  
Vijayshekar pulusu ◽  
Chinna Rajanna Rajanna Kamatala ◽  
Anil Kumar Mardhanpally ◽  
Hemanth Sriram Yel ◽  
Yaku Guguloth ◽  
...  
Keyword(s):  
Aromatic Compounds ◽  
Reaction Times ◽  
Solvent Free ◽  
Microwave Assisted ◽  
Rate Acceleration ◽  
Solvent Free Conditions ◽  
Ultrasonic Assisted

Abstract Silica supported nanogreenacids like Si-KHSO4, and Si-HClO4are explored as reusable catalysts for bromination of aromatic and hetero aromatic compounds using KBr under solvothermal, and solvent-free conditions. Reaction times reduced from Reacions under conventional solvothermal protocols conditions required (4 – 6) hours, while ultrasonic assisted reactions only (9 – 12) minutes for completion. But, solvent-free microwave assisted reactions required only (1-5) minutes exhibiting striking rate acceleration compared to the solvothermal and ultrasonic assisted protocols All the reaction protocols afforded fairly good yields of brominated products, which are comparable with existing protocols.

scholarly journals Syntheses of 3,4- and 1,4-dihydroquinazolines from 2-aminobenzylamine

2017 ◽  
Vol 13 ◽  
pp. 1470-1477 ◽  
Author(s):  
Jimena E Díaz ◽  
Silvia Ranieri ◽  
Nadia Gruber ◽  
Liliana R Orelli
Keyword(s):  
Reaction Times ◽  
Ring Closure ◽  
Cesium Carbonate ◽  
Amino Groups ◽  
Microwave Assisted ◽  
Common Precursor ◽  
Alkylation Reactions

A straightforward strategy for the synthesis of dihydroquinazolines is presented, which allows for the preparation of 3,4- and 1,4-dihydroquinazolines with different substitution patterns from 2-aminobenzylamine (2-ABA) as common precursor. The required functionalization of both amino groups present in 2-ABA was achieved by different routes involving selective N-acylation and cesium carbonate-mediated N-alkylation reactions, avoiding protection/deprotection steps. The heterocycles were efficiently synthesized in short reaction times by microwave-assisted ring closure of the corresponding aminoamides promoted by ethyl polyphosphate (PPE).

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