A Facile Microwave and SnCl2 Synthesis of 2,3-Dihydroquinazolin-4(1H)-ones

2020 ◽  
Vol 73 (12) ◽  
pp. 1176
Author(s):  
Nicholas S. O'Brien ◽  
Adam McCluskey
Keyword(s):  
Microwave Irradiation ◽  
Diels Alder ◽  
Electrophilic Addition ◽  
Pure Material ◽  
Robust Approach ◽  
Unsaturated Aldehydes ◽  
Biological Importance ◽  
High Yields ◽  
Aromatic Heterocyclic

An elegantly simple, facile, and robust approach to a scaffold of biological importance, 2,3-dihydroquinazolin-4(1H)-ones, is reported. A catalytic 1% SnCl2/microwave-mediated approach afforded access to pure material, collected by cooling and filtration after 20-min microwave irradiation at 120°C. A total of 41 analogues were prepared in isolated yields of 17–99%. This process was highly tolerant of aliphatic, aromatic, heterocyclic, and acyclic aldehydes, but furan, pyrrole, and thiophene aldehyde reactivity correlated with propensity towards electrophilic addition and/or Diels–Alder addition. As a result, thiophene afforded high yields (80%) whereas pyrrole carboxaldehyde failed to react. With simple cinnamaldehydes, and in the SbCl3-mediated reaction, and with α,β-unsaturated aldehydes the equivalent quinazolin-4(3H)-ones, and not the 2,3-dihydroquinazolin-4(1H)-ones, was favoured.

Green Formation of Novel Pyridinyltriazole-Salicylidene Schiff Bases

2019 ◽  
Vol 16 (2) ◽  
pp. 309-313
Author(s):  
Mustafa Kemal Gümüş
Keyword(s):  
Microwave Irradiation ◽  
Schiff Bases ◽  
Guanidine Hydrochloride ◽  
Alternative Methods ◽  
Second Step ◽  
Green Method ◽  
Maximum Reaction ◽  
Pyridine Carboxylic ◽  
High Yields ◽  
Amine Hydrochlorides

Aim and Objective: In this work, water was used as solvent for the eco-friendly synthesis of imines under microwave irradiation. In the first step of the study, 5-pyridinyl-3-amino-1,2,4-triazole hydrochlorides were synthesized in the reaction of amino guanidine hydrochloride with different pyridine carboxylic acids under acid catalysis. A green method for 5-pyridinyl-3-amino-1,2,4-triazoles was developed with the assistance of microwave synthesis. In the second step, the eco-friendly synthesis of imines was achieved by reacting 5- pyridinyl-2H-1,2,4-triazol-3-amine hydrochlorides with salicylic aldehyde derivatives to produce 2-(5- pyridinyl-2H-1,2,4-triazol-3-ylimino)methyl)phenol imines. Materials and Methods: Microwave experiments were done using a monomode Anton Paar Monowave 300 microwave reactor (2.45 GHz). Reaction temperatures were monitored by an IR sensor. Microwave experiments were carried out in sealed microwave process vials G10 with maximum reaction volume of 10 mL. Results: When alternative methods were used, it was impossible to obtain good yields from ethanol. Nevertheless, the use of water was successful for this reaction. After 1-h microwave irritation, a yellow solid was obtained in 82% yield. Conclusion: In this work an eco-friendly protocol for the synthesis of Schiff bases from 5-(pyridin-2-, 3- or 4- yl)-3-amino-1,2,4-triazoles and substituted salicylic aldehydes in water under microwave irradiation was developed. Under the found conditions the high yields for the products were achieved at short reaction time and with an easy isolation procedure.

scholarly journals Theoretical Insight into the Reversal of Chemoselectivity in Diels-Alder Reactions of α,β-Unsaturated Aldehydes and Ketones Catalyzed by Brønsted and Lewis Acids

Organics ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 38-49
Author(s):  
Lakhdar Benhamed ◽  
Sidi Mohamed Mekelleche ◽  
Wafaa Benchouk
Keyword(s):  
Lewis Acids ◽  
Major Product ◽  
Diels Alder ◽  
Unsaturated Ketone ◽  
Unsaturated Aldehydes ◽  
Aldehydes And Ketones ◽  
Theoretical Insight ◽  
Insight Into ◽  
Good Agreement

Experimentally, a reversal of chemoselectivity has been observed in catalyzed Diels–Alder reactions of α,β-unsaturated aldehydes (e.g., (2E)-but-2-enal) and ketones (e.g., 2-hexen-4-one) with cyclopentadiene. Indeed, using the triflimidic Brønsted acid Tf2NH as catalyst, the reaction gave a Diels–Alder adduct derived from α,β-unsaturated ketone as a major product. On the other hand, the use of tris(pentafluorophenyl)borane B(C6F5)3 bulky Lewis acid as catalyst gave mainly the cycloadduct of α,β-unsaturated aldehyde as a major product. Our aim in the present work is to put in evidence the role of the catalyst in the reversal of the chemoselectivity of the catalyzed Diels–Alder reactions of (2E)-but-2-enal and 2-Hexen-4-one with cyclopentadiene. The calculations were performed at the ωB97XD/6-311G(d,p) level of theory and the solvent effects of dichloromethane were taken into account using the PCM solvation model. The obtained results are in good agreement with experimental outcomes.

Reactivity of 3-Styrylchromones as Dienes in Diels—Alder Reactions under Microwave Irradiation: A New Synthesis of Xanthones.

ChemInform ◽  
2005 ◽  
Vol 36 (44) ◽  
Author(s):  
Diana C. G. A. Pinto ◽  
Artur M. S. Silva ◽  
Cristela M. Brito ◽  
Angela Sandulache ◽  
Jose R. Carrillo ◽  
...  
Keyword(s):  
Microwave Irradiation ◽  
Diels Alder ◽  
New Synthesis

Synthesis and Application of Tetrafluoroethylene (CF2CF2)-Containing Acetylene Derivatives

Synthesis ◽  
2020 ◽  
Vol 52 (13) ◽  
pp. 1947-1958
Author(s):  
Tsutomu Konno ◽  
Gen Egashira ◽  
Chihiro Kajimoto ◽  
Takuto Kataoka ◽  
Shigeyuki Yamada
Keyword(s):  
Coupling Reaction ◽  
Cross Coupling ◽  
Alder Reaction ◽  
Diels Alder ◽  
Benzene Derivatives ◽  
Diels Alder Reaction ◽  
Cross Coupling Reaction ◽  
Oxidative Aromatization ◽  
High Yields ◽  
Acetylene Derivatives

On treating 1,3,4-tribromo-1,1,2,2-tetrafluorobutane, readily prepared from commercially available 4-bromo-3,3,4,4-tetrafluorobut-1-ene, with 3.3 equivalents of LHMDS at 0 °C in THF, the corresponding lithium acetylide could be prepared quantitatively. The acetylide reacted well with various aldehydes, ketones, or chlorosilanes to give the corresponding acetylene derivatives in high yields. It was also found that various iodoarenes could participate in the cross-coupling reaction with the zinc acetylide, readily prepared from the lithium acetylide and ZnCl2·TMEDA complex, in the presence of Pd(PPh3)4 to bring about the adducts in high yields. Thus-obtained acetylene derivatives underwent smooth Diels–Alder reaction with various 1,3-dienes to afford the corresponding 1,4- or 1,3-cyclohexadiene derivatives. In addition, it was revealed that the oxidative aromatization of the resulting cyclohexadiene derivatives with DDQ took place very smoothly, providing the multi-substituted benzene derivatives having a tetrafluoro­ethylene group.

ChemInform Abstract: Diels-Alder Cycloaddition of 4,6-Dimethyl-1,2,3-triazine with Enamines, or Their Precursors, under Microwave Irradiation.

ChemInform ◽  
2010 ◽  
Vol 32 (22) ◽  
pp. no-no
Author(s):  
Angel Diaz-Ortiz ◽  
Antonio de la Hoz ◽  
Pilar Prieto ◽  
Jose R. Carrillo ◽  
Andres Moreno ◽  
...  
Keyword(s):  
Microwave Irradiation ◽  
Diels Alder

scholarly journals Microwave Assisted Synthesis of 1,5-Benzothiazepines Using Greener Reaction Medium

2019 ◽  
Vol 31 (5) ◽  
pp. 993-996 ◽  
Author(s):  
Sanjay S. Kotalwar ◽  
Amol D. Kale ◽  
Ram B. Kohire ◽  
Vasant B. Jagrut
Keyword(s):  
Reaction Time ◽  
Microwave Irradiation ◽  
Reaction Medium ◽  
Microwave Assisted Synthesis ◽  
Reaction Conditions ◽  
Renewable Sources ◽  
Microwave Assisted ◽  
High Yields

An efficient and eco-friendly synthesis of 1,5-benzothiazepines has been developed by the reaction of various 2-propen-1-ones with 2-aminothiophenol using microwave irradiation in greener reaction medium, glycerol. The clean reaction conditions, shorter reaction time, high yields and non-toxic, biodegradable reaction medium manufactured from renewable sources are unique features of this method.

Heterogeneous Catalysis with Basic Compounds to Achieve the Synthesis and C–N Cleavage of Azetidin-2-ones under Microwave Irradiation

Synthesis ◽  
2019 ◽  
Vol 51 (19) ◽  
pp. 3625-3637 ◽  
Author(s):  
Adriana Galván ◽  
Fabiola N. de la Cruz ◽  
Francisco Cruz ◽  
Merced Martínez ◽  
Clarisa Villegas Gomez ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Heterogeneous Catalysis ◽  
Microwave Irradiation ◽  
Bond Cleavage ◽  
Reaction Times ◽  
Organic Additives ◽  
Acyl Chlorides ◽  
Solid Catalysts ◽  
Basic Compounds ◽  
High Yields

The synthesis of azetidin-2-ones with a completely heterogeneous catalysis is reported. The use of basic compounds as solid catalysts allowed for the synthesis of azetidin-2-ones under microwave irradiation without organic additives such as triethylamine. An excellent catalyst for this transformation was Mg-Al hydroxide (MAH). The present methodology offers the advantages of non-hazardous reaction conditions, short reaction times, high yields, and catalyst reusability. Different substitution groups were tested on the imines and acyl chlorides to explore the scope of the reaction. Unconventional N–C4 bond cleavage was detected in azetidin-2-ones. MAH was characterized by N2 adsorption–desorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HR-TEM).

Copper(i)/TF-BiphamPhos catalyzed asymmetric nitroso Diels–Alder reaction

2017 ◽  
Vol 53 (10) ◽  
pp. 1657-1659 ◽  
Author(s):  
Jun Li ◽  
Hai-Yan Tao ◽  
Chun-Jiang Wang
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Highly Efficient ◽  
Diels Alder Reaction ◽  
Cyclic Dienes ◽  
High Yields

A highly efficient enantioselective nitroso Diels–Alder reaction of 6-methyl-2-nitroso pyridine with various 1,3-dienes was successfully developed using a copper(i)/(S)–TF-BiphamPhos complex as the catalyst. For most of the cyclic dienes, the cycloadducts were obtained in high yields with excellent regio-, and stereoselectivities. Acyclic 2-silyloxy-1,3-diene also worked well in the reaction.

scholarly journals Regioselective synthesis of benzonitriles via amino-catalyzed [3+3] benzannulation reaction

2020 ◽  
Vol 44 (9-10) ◽  
pp. 592-597
Author(s):  
Lin Jiang ◽  
Wen-Fei Jin ◽  
Liu-Dong Yu ◽  
Ming-Wei Yuan ◽  
Hong-Li Li ◽  
...  
Keyword(s):  
Environmentally Friendly ◽  
Regioselective Synthesis ◽  
Reaction Conditions ◽  
Unsaturated Aldehydes ◽  
High Yields ◽  
Environmentally Friendly Method

A straightforward synthesis of benzonitriles is achieved via amino-catalyzed [3+3] benzannulation of α,β-unsaturated aldehydes and 4-arylsulfonyl-2-butenenitriles. Using pyrrolidine as an organocatalyst via iminium activation, a series of substituted benzonitriles were obtained in good to high yields in a regioselective manner. This reaction can proceed smoothly under mild reaction conditions and without the aid of any metals, additional oxidants, or strong bases, thus making this an efficient and environmentally friendly method to access benzonitriles.

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