scholarly journals Oxidative cycloaddition of hydroxamic acids with dienes or guaiacols mediated by iodine(III) reagents

2018 ◽  
Vol 14 ◽  
pp. 531-536 ◽  
Author(s):  
Hisato Shimizu ◽  
Akira Yoshimura ◽  
Keiichi Noguchi ◽  
Victor N Nemykin ◽  
Viktor V Zhdankin ◽  
...  
Keyword(s):  
Present Method ◽  
Hydroxamic Acids ◽  
Diels Alder ◽  
Oxidative Dearomatization ◽  
High Yields

[Bis(trifluoroacetoxy)iodo]benzene (BTI) and (diacetoxyiodo)benzene (DIB) efficiently promote the formation of acylnitroso species from hydroxamic acids in the presence of various dienes to give the corresponding hetero-Diels–Alder (HDA) adducts in moderate to high yields. The present method could be applied to the HDA reactions of acylnitroso species witho-benzoquinones generated by the oxidative dearomatization of guaiacols.

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.

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.

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.

TiO2–SiO2 nanocomposite as a highly efficient catalyst for the solvent-free cyclocondensation reaction of isatins, cyclohexanones, and urea

2019 ◽  
Vol 74 (7-8) ◽  
pp. 559-564
Author(s):  
Simin Janitabar-Darzi ◽  
Shahrzad Abdolmohammadi
Keyword(s):  
Present Method ◽  
High Efficiency ◽  
Solvent Free ◽  
High Catalytic Activity ◽  
One Pot ◽  
Efficient Catalyst ◽  
Solvent Free Conditions ◽  
Cyclocondensation Reaction ◽  
The One ◽  
High Yields

AbstractA TiO2–SiO2 nanocomposite catalyzes the one-pot cyclocondensation reaction of 1H-indole-2,3-diones (isatins), 1,3-cyclohexanediones, and urea at T = 70°C under solvent-free conditions with high efficiency. The present method affords the corresponding spiro products in high yields and short reaction time. The unique features of the TiO2–SiO2 nanocomposite are high catalytic activity, ease of preparation, non-toxicity, low loading, and recyclability.

scholarly journals Diels - Alder Reactions of 3-Furylamines in Organic and Aqueous Solvents

2006 ◽  
Vol 59 (5) ◽  
pp. 336 ◽  
Author(s):  
Anthony R. Lingham ◽  
Helmut M. Hügel ◽  
Trevor J. Rook
Keyword(s):  
Methyl Acrylate ◽  
Aqueous Media ◽  
Diels Alder ◽  
High Yields

Various 5-methyl-3-aminofurans have been shown to undergo facile Diels–Alder reactions with methyl acrylate in aqueous media. Reactions proceeded with exclusive regiochemistry, and enamine cycloadducts were readily hydrolyzed to afford 7-oxabicyclo[2.2.1]heptanones in high yields.

scholarly journals NaOH/PEG-400: An eloquent system for the synthesis of new thienyl benzo[b]1,4-diazepines

2020 ◽  
Vol 11 (4) ◽  
pp. 276-279
Author(s):  
Gajanan Gopinath Mandawad ◽  
Baseer Mubeen Shaikh ◽  
Santosh Subhash Chobe ◽  
Shankaraiah Guruvaiah Konda
Keyword(s):  
Polyethylene Glycol ◽  
Reaction Time ◽  
Present Method ◽  
Spectroscopic Methods ◽  
Reaction Conditions ◽  
Environment Friendly ◽  
Peg 400 ◽  
High Yields ◽  
Work Up

A simple and eloquent procedure for the synthesis of a new series of thienyl benzo[b]1,4-diazepines is reported. They were synthesized by the condensation of o-phenylenediamine (o-PDA) with distinct hetero chalcones using NaOH in polyethylene glycol (PEG-400) as green and alternative reaction solvent. The significances of this present method are shorter reaction time, easy work-up, high yields, and mild reaction conditions. Furthermore, this method is environment friendly and without use of an expensive catalyst. The all newly synthesized compounds are characterized by the spectroscopic methods.

scholarly journals Infrared Irradiation-Assisted Multicomponent Synthesis of 2-Amino-3-cyano-4H-pyran Derivatives

2017 ◽  
Vol 56 (2) ◽  
Author(s):  
Arturo Sánchez ◽  
Fernando Hernández ◽  
Paulo César Cruz ◽  
Yolanda Alcaraz ◽  
Joaquín Tamariz ◽  
...  
Keyword(s):  
Ethyl Acetoacetate ◽  
Present Method ◽  
Reaction Times ◽  
Ammonium Hydroxide ◽  
Infrared Irradiation ◽  
Efficient Synthesis ◽  
Multicomponent Synthesis ◽  
Reaction Conditions ◽  
High Yields ◽  
Pyran Derivative

A simple, versatile, and efficient synthesis of 4<em>H</em>-pyran derivative compounds is achieved via a three-component cyclocondensation of aldehydes, malononitrile, and ethyl acetoacetate, using ammonium hydroxide as the catalyst, promoted by infrared irradiation. The present method offers several advantages, such as high yields, non hazardous reaction conditions as well as short reaction times.

scholarly journals Enzymatic C-N Bond Formation via Aerobic Nitroso Ene Reactions

2021 ◽  
Author(s):  
Jan Deska ◽  
Christina Jäger
Keyword(s):  
Bond Formation ◽  
Reactive Intermediates ◽  
Hydroxamic Acids ◽  
Reaction Pathways ◽  
Ene Reactions ◽  
High Yields ◽  
Aqueous Conditions ◽  
Biocatalytic Promiscuity

<p><i>A novel biocatalytic protocol enables the direct and selective introduction of nitrogen functionalities via activation of allylic C-H bonds. Utilizing an oxidase/peroxidase couple for the formal dehydrogenation of N-hydroxycarbamates and hydroxamic acids with air as terminal oxidant, acylnitroso species are generated under particularly mild aqueous conditions. The reactive intermediates undergo C-N bond formation through an ene-type mechanism and provide high yields both in intramolecular and intermolecular enzymatic aminations. Investigations on alternative reaction pathways and labelling studies provide more insights into this unprecedented biocatalytic promiscuity of classical oxidoreductases as catalysts for nitroso ene-based transformations.</i></p>

scholarly journals Synthesis of dibenzosuberenone-based novel polycyclic π-conjugated dihydropyridazines, pyridazines and pyrroles

2021 ◽  
Vol 17 ◽  
pp. 719-729
Author(s):  
Ramazan Koçak ◽  
Arif Daştan
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Cycloaddition Reactions ◽  
Inverse Electron Demand ◽  
Diels Alder Reaction ◽  
Reductive Treatment ◽  
High Yields ◽  
Derivatives Of ◽  
Electron Demand

The synthesis of novel polycyclic π-conjugated dihydropyridazines, pyridazines, and pyrroles was studied. Dihydropyridazine dyes were synthesized by inverse electron-demand Diels–Alder cycloaddition reactions between a dibenzosuberenone and tetrazines that bear various substituents. The pyridazines were synthesized in high yields by oxidation of dihydropyridazine-appended dibenzosuberenones with PIFA or NO. p-Quinone derivatives of pyridazines were also obtained by H-shift isomerization following the inverse electron-demand Diels–Alder reaction of tetrazines with p-quinone dibenzosuberenone. Then these pyridazines were converted to the corresponding pyrroles by reductive treatment with zinc. It was observed that all the dihydropyridazines obtained gave absorbance and emission at long wavelengths.

Direct NMR evidence for the equivalent participation of L-phenylalanine and L-tyrosine in the biosynthesis of the intermolecular Diels–Alder type adducts of prenylchalcone and prenylated 2-arylbenzofuran in Morus alba cell cultures

1994 ◽  
Vol 72 (1) ◽  
pp. 12-14 ◽  
Author(s):  
Yoshio Hano ◽  
Taro Nomura ◽  
Shinichi Ueda
Keyword(s):  
Amino Acids ◽  
Cell Cultures ◽  
Nmr Spectra ◽  
Diels Alder ◽  
Morus Alba ◽  
High Yields ◽  
C Nmr

L-[3-13C]Phenylalanine and L-[3-13C]tyrosine were administered to Morus alba cell cultures, to produce intermolecular Diels–Alder type adducts of a prenylchalcone and a 2-arylbenzofuran such as chalcomoracin (1) as well as the adducts of two molecules of prenylchalcones such as kuwanon J (2) in high yields. The 13C NMR spectra of 1 and 2 isolated from the cultures revealed that both amino acids were incorporated intact into chalcomoracin (1) and kuwanon J (2). This is the first example of direct NMR evidence for the almost equivalent incorporation of phenylalanine and tyrosine into the shikimate metabolites. This finding suggests the participation of a biosynthetic route from phenylalanine via trans-cinnamate to p-coumarate and from tyrosine to p-coumarate in this plant.

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