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.

Hydrolysis of amides to carboxylic acids using phthalic anhydride under microwave irradiation and solvent-free conditions

2005 ◽  
Vol 2005 (2) ◽  
pp. 119-120 ◽  
Author(s):  
Majid M. Heravi ◽  
Dordaneh Zargarani ◽  
Rahim Hekmat Shoar ◽  
Shahnaz Khaleghi
Keyword(s):  
Microwave Irradiation ◽  
Carboxylic Acids ◽  
Phthalic Anhydride ◽  
Solvent Free ◽  
Solvent Free Conditions ◽  
High Yields ◽  
Hydrolysis Of

Amides efficiently and rapidly give carboxylic acids in high yields upon reaction with phthalic anhydride under microwave irradiation in the absence of solvent.

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.

scholarly journals Tandem Fries Reaction–Conjugate Addition under Microwave Irradiation in Dry Media; One-pot Synthesis of Flavanones

1999 ◽  
Vol 23 (9) ◽  
pp. 574-575
Author(s):  
Firouz Matloubi Moghaddam ◽  
Mohammad Ghaffarzadeh ◽  
Seyed Hossein Abdi-Oskoui
Keyword(s):  
Microwave Irradiation ◽  
Silica Gel ◽  
Conjugate Addition ◽  
Solvent Free ◽  
Naphthalene Derivatives ◽  
One Pot ◽  
Fries Rearrangement ◽  
One Pot Synthesis ◽  
Solvent Free Conditions ◽  
Fries Reaction

An AICl3–ZnCl2 mixture supported on silica gel is found to be an efficient medium for the Fries rearrangement of acyloxybenzene or naphthalene derivatives in solvent-free conditions under microwave irradiation.

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.

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