Efficient, microwave-assisted intramolecular 1,3-dipolar cycloadditions of oximes and N-methylnitrones derived from o-alkenylmethoxy-acetophenones

2005 ◽  
Vol 83 (3) ◽  
pp. 260-265 ◽  
Author(s):  
Surinderjit Singh ◽  
M PS Ishar ◽  
Gajendra Singh ◽  
Rajinder Singh
Keyword(s):  
Microwave Irradiation ◽  
Microwave Heating ◽  
Reaction Times ◽  
Solvent Free ◽  
Dipolar Cycloadditions ◽  
Microwave Assisted ◽  
Solvent Free Conditions ◽  
A Minor ◽  
Acetophenone Oxime

Contrary to literature reports, the o-allyloxy- and crotyloxy-acetophenone-oximes (2a, 2b) are transformed to nitrones, which undergo regio- and stereoselective intramolecular 1,3-dipolar cycloadditions, both on microwave heating under solvent free conditions and refluxing in toluene, to afford novel cycloadducts (5a, 5b); the oxazepine-N-oxide (3a) reported to be formed in 98% yield was obtained only as a minor product (~10%). However, o-cinnamyloxy-acetophenone-oxime (2c) under similar conditions undergoes intramolecular N-alkylation to afford nitrone (3c). The reactions carried out under microwave irradiation are cleaner, require shorter reaction times, and have higher yields. Corresponding intramolecular 1,3-dipolar cycloadditions of N-methylnitrones (B), generated in situ from o-alkenylmethoxy-acetophenones (1a–1c) and N-methylhydroxylamine under solvent-free microwave irradiation conditions, are completely regio- and stereoselective, require much shorter reaction times, and afford adducts (4a–4c) in higher yields, as compared with their thermal counterparts.Key words: cycloadditions, nitrones, oximes, o-alkenylmethoxy-acetophenones, microwave, isoxazolidines.

A simple and eco-sustainable method for the sulfonylation of amines under microwave-assisted solvent-free conditions

RSC Advances ◽  
2014 ◽  
Vol 4 (31) ◽  
pp. 16027-16032 ◽  
Author(s):  
Salah Lakrout ◽  
Hacène K'tir ◽  
Aïcha Amira ◽  
Malika Berredjem ◽  
Nour-Eddine Aouf
Keyword(s):  
Microwave Irradiation ◽  
Reaction Times ◽  
Solvent Free ◽  
Environmentally Benign ◽  
Microwave Assisted ◽  
Catalyst Free ◽  
Solvent Free Conditions

A new environmentally benign, simple, and efficient protocol for the sulfonylation of amines using microwave irradiation under solvent- & catalyst-free conditions is reported. The corresponding sulfonamides were obtained in excellent yields within short reaction times.

scholarly journals TMSOTf-catalyzed synthesis of trisubstituted imidazoles using hexamethyldisilazane as a nitrogen source under neat and microwave irradiation conditions

RSC Advances ◽  
2021 ◽  
Vol 11 (45) ◽  
pp. 28061-28071
Author(s):  
Kesatebrhan Haile Asressu ◽  
Chieh-Kai Chan ◽  
Cheng-Chung Wang
Keyword(s):  
Microwave Irradiation ◽  
Nitrogen Source ◽  
Microwave Heating ◽  
Solvent Free ◽  
Solvent Free Conditions

Trisubstituted imidazoles are synthesized efficiently from the readily available 1,2-diketones and aldehydes using hexamethyldisilazane as a new and stable nitrogen source under TMSOTf-catalysis system, microwave heating and solvent-free conditions.

Microwave-assisted synthesis of quinolones and 4H-1,4-benzo thiazine 1,1-dioxides

2005 ◽  
Vol 2005 (1) ◽  
pp. 27-28 ◽  
Author(s):  
Jaime Charris ◽  
Arthur Barazarte ◽  
José Domínguez ◽  
Neira Gamboa
Keyword(s):  
Microwave Irradiation ◽  
Rapid Method ◽  
Solvent Free ◽  
Microwave Assisted Synthesis ◽  
Microwave Assisted ◽  
Solvent Free Conditions

A rapid method for the preparation of N-aryl-2-methylthio-4-oxo-1,4-dihydro quinoline-3-carbonitriles (2a–e) and N-aryl-3-methylthio-4H-1,4-benzothiazine-2-carbonitrile 1,1-dioxides (2f–o) is reported. The cyclization is accelerated by microwave irradiation under solvent free conditions in the presence of K2CO3.

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.

A One-Pot, Three-Component, Solvent-Free Synthesis of Novel 6H-Chromeno[3’,4’:5,6]Pyrido[2,3-d]Pyrimidine-Triones under Microwave Irradiation

2018 ◽  
Vol 42 (12) ◽  
pp. 604-607
Author(s):  
Loghman Firoozpour ◽  
Hoda Yahyavi ◽  
Ramona Ejtemaei ◽  
Setareh Moghimi ◽  
Alireza Foroumadi
Keyword(s):  
Microwave Irradiation ◽  
Efficient Method ◽  
Barbituric Acid ◽  
Reaction Times ◽  
Solvent Free ◽  
One Pot ◽  
Solvent Free Conditions ◽  
Substituted Benzaldehydes ◽  
High Yields ◽  
Solvent Free Synthesis

A green and efficient method for preparing novel heterocyclic systems is established through the reaction of differently substituted benzaldehydes, barbituric acid and 4-amino-2H-chromene-2-one under solvent-free conditions. This method affords 6H-chromeno[3’,4’:5,6] pyrido[2,3-d]pyrimidine-trione derivatives in high yields and short reaction times.

Microwave-assisted synthesis of 1,4-disubstituted thiosemicarbazides and semicarbazides under solvent-free conditions in the absence of catalyst

2005 ◽  
Vol 2005 (1) ◽  
pp. 71-72 ◽  
Author(s):  
Xi-Cun Wang ◽  
Zheng-Jun Quan ◽  
Zheng Li
Keyword(s):  
Microwave Irradiation ◽  
Solvent Free ◽  
Microwave Assisted Synthesis ◽  
Microwave Assisted ◽  
Solvent Free Conditions

Thirty-two 1-aroyl/aryloxyacetyl-4-(2-furoyl)thiosemicarbazides and corresponding semicarbazides were synthesised in excellent yields under microwave irradiation and solvent-free conditions without using any catalyst.

1,3-Dibromo-5,5-dimethylhydantoin as a useful reagent for efficient synthesis of 3,4-dihydropyrimidin-2-(1H)-ones under solvent-free conditions

2009 ◽  
Vol 63 (1) ◽  
Author(s):  
Mohammad Abdollahi-Alibeik ◽  
Zahra Zaghaghi
Keyword(s):  
Microwave Irradiation ◽  
Ethyl Acetoacetate ◽  
Biginelli Reaction ◽  
Reaction Times ◽  
Solvent Free ◽  
Efficient Synthesis ◽  
One Pot ◽  
Aliphatic Aldehydes ◽  
Solvent Free Conditions ◽  
High Yields

AbstractEfficient syntheses of 3,4-dihydropyrimidin-2-(1H)-ones and the corresponding thioxo derivatives using 1,3-dibromo-5,5-dimethylhydantoin (DBH) catalysis of a one-pot three-component Biginelli reaction of aldehydes, ethyl acetoacetate, and urea or thiourea under microwave irradiation are described. The advantages of this method are its short reaction times, high yields of the products, inexpensive and commercially available catalyst, and solvent-free conditions. Typical isolated yields exceed 70 % for arylaldehydes (9 examples) and aliphatic aldehydes (2 examples).

A sulfonated Schiff base dimethyltin(iv) coordination polymer: synthesis, characterization and application as a catalyst for ultrasound- or microwave-assisted Baeyer–Villiger oxidation under solvent-free conditions

RSC Advances ◽  
2016 ◽  
Vol 6 (81) ◽  
pp. 78225-78233 ◽  
Author(s):  
Luísa M. D. R. S. Martins ◽  
Susanta Hazra ◽  
M. Fátima C. Guedes da Silva ◽  
Armando J. L. Pombeiro
Keyword(s):  
Schiff Base ◽  
Coordination Polymer ◽  
Microwave Irradiation ◽  
Heterogeneous Catalyst ◽  
Polymer Synthesis ◽  
Solvent Free ◽  
Microwave Assisted ◽  
Solvent Free Conditions ◽  
Villiger Oxidation ◽  
Efficient Heterogeneous Catalyst

The sulfonated Schiff base dimethyltin(iv) coordination polymer is an efficient heterogeneous catalyst for the peroxidative Baeyer–Villiger oxidation of ketones, under ultrasound or microwave irradiation and solvent- and additive-free conditions.

scholarly journals Investigation on the reactivity of α-azidochalcones with carboxylic acids: Formation of α-amido-1,3-diketones and highly substituted 2-(trifluoromethyl)oxazoles

2015 ◽  
Vol 11 ◽  
pp. 2021-2028 ◽  
Author(s):  
Kandasamy Rajaguru ◽  
Arumugam Mariappan ◽  
Rajendran Suresh ◽  
Periasamy Manivannan ◽  
Shanmugam Muthusubramanian
Keyword(s):  
Microwave Irradiation ◽  
Carboxylic Acids ◽  
Trifluoroacetic Acid ◽  
Solvent Free ◽  
Solvent Free Conditions ◽  
In Situ Formation ◽  
Lower Temperature

The reaction of α-azidochalcones with carboxylic acids has been investigated resulting in the formation of α-amido-1,3-diketones under microwave irradiation via in situ formation of 2H-azirine intermediates. An interesting reaction is described wherein, with trifluoroacetic acid at lower temperature, it affords highly substituted 2-(trifluoromethyl)oxazoles. These flexible transformations proceed under solvent free conditions in good to excellent yields without any catalyst.

Solvent-Free, Microwave-Assisted Conversion of Tosylates into Iodides

2014 ◽  
Vol 67 (9) ◽  
pp. 1360 ◽  
Author(s):  
Jia Cao ◽  
Patrick Perlmutter
Keyword(s):  
Efficient Method ◽  
Sodium Iodide ◽  
Reaction Times ◽  
Solvent Free ◽  
Microwave Cavity ◽  
Microwave Assisted ◽  
Crude Product ◽  
In Situ Generation ◽  
High Yields

A highly efficient method for the conversion of primary tosylates into the corresponding iodides is outlined. The method involves heating a neat mixture of the tosylate and solid sodium iodide in a microwave cavity. Reaction times are short, usually about 60 minutes, delivering high yields. This procedure is especially useful for the in situ generation of volatile primary iodides, and for most of the primary iodides, the crude product is sufficiently pure.

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