Neighboring group participation in cyclodehydration. A regiospecific isoxazole synthesis

Crawley, L.; Fanshawe, William J.

doi:10.1002/jhet.5570140339

Cited by 15 publications

(3 citation statements)

References 2 publications

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“…Thiazines 4 and oxazines 5 can be synthesized by reaction of chalcones 1 with thiourea and urea, respectively [45] (Scheme 3). Pyrazoles 6, 7 are obtained through the reaction of chalcones 1 with hydrazine hydrate and phenyl hydrazine derivatives, respectively [46]- [49] using Lewis acid (1.0 equivalent of BF 3 •Et 2 O) in refluxing ethanol under anhydrous conditions afforded 1H-pyrazolo [3,4-b]pyridines 11 in very good yields and short reaction time [52] (Scheme 4). Similarly, treatment of 1 with ethyl cyanoacetate in absolute ethanol and in the presence of ammonium acetate afforded cyanopyridine derivatives 12 [49] (Scheme 3).…”

Section: Reactivity Of Chalcone Derivativesmentioning

confidence: 99%

Arylidene Derivatives as Synthons in Heterocyclic Synthesis

El‐Gohary¹

2014

OALib

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This review describes the synthetic procedures for the preparation of arylideneacetophenones, arylidenecycloalkanones, 2-arylidene-1-indanones, 2-arylidene-1-tetralones, 2-arylidene-1-benzosuberones, aurones, 1-thioaurones, 3-arylidene-4-chromanones, 3-arylidene-1-thio-4-chromanones, 3-arylideneflavanones, 3-arylidene-1-thioflavanones, arylideneanilines, arylidenemalononitriles, diethyl arylidenemalonates, ethyl arylidenecyanoacetates, arylidenecyanoacetamides, 5arylidene derivatives of barbituric and thiobarbituric acids, arylidene derivatives of Meldrum's acid and arylidene derivatives of dimedone. Also, it demonstrates the reactivity of these arylidene derivatives in heterocyclic synthesis with emphasis on the most recent findings. Some of these are the α,β-enones, víz. aurones and 3-arylidene-4-chromanones belong to the natural products. The others are synthetic substances which are convenient and important intermediates for the synthesis of a variety of useful and novel heterocyclic systems.

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Section: Reactivity Of Chalcone Derivativesmentioning

confidence: 99%

Arylidene Derivatives as Synthons in Heterocyclic Synthesis

El‐Gohary¹

2014

OALib

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“…Further ring closure reactions of Chalcones can be used to obtain various heterocyclic rings viz. ; Pyrazoles, Pyrans, Cyanopyridines, isoxazoles and pyrimidines having different hetero-cyclic ring systems and multiple derivatives can be synthesized using chalcones [11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Green Synthesis of Chalcone Derivatives Using Chalcones as Precursor

Dhadda¹,

Goswami²,

Sharma³

2022

Green Chemistry - New Perspectives

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Recently, the use of green methodologies like sonication, use of ionic liquids, etc. attracted the attention of researchers in the field of organic synthesis as they have advantages such as mild reaction conditions, environmentally benign procedures, etc. Herein, this chapter highlights some recyclable ionic liquids (ILs) catalyzed ring closure reactions of chalcones to obtain several heterocyclic rings viz.; pyrazoles, pyrans, pyrimidines under ultrasonification. These reactions have very important features i.e., short routine, high yields, being environmentally friendly, high functional group tolerance, formation of a single product, high atom economy, high yielding, no need for column purification, etc. The various synthesized compounds were prepared in optimized reaction conditions in good to efficient yields. Analytical and spectral (FTIR, 1H, and 13C NMR) techniques were employed for the structural elucidation of the synthesized compounds. The ionic liquids used in the synthesis are recycled and reused several times.

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“…[6] They are used to synthesized several derivatives such as cyanopyridines, pyrazolines, isoxazoles, and pyrimidines having different heterocyclic ring systems. [7][8][9][10] Chalcone moieties are available in natural as well as synthetic compounds and are found to display a variety of pharmacological activity such as antibacterial, antitumor, anticancer, antituberculosis, anti-inflammatory, antioxidant, antimalarial, and anti-ulcerative. [11,12] The presence of reactive methoxy and hydroxyl groups in the chalcone backbone is responsible for their biological activity.…”

Section: Introductionmentioning

confidence: 99%

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Rais¹

2018

AJP

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Aim: To synthesise random copolyesters containing chalcone moiety in the main chain, their characterization and biological activity. Material and Methods: A series of eight random copolyesters were synthesized by the polycondensation of a chalcone diol with two aromatic diacid chlorides and four aliphatic diacid chlorides. The two aromatic diacid chlorides used were terephthaloyl chloride and isophthaloyl chloride. The aliphatic diacid chlorides used were adipoyl chloride, oxalyl chloride, glutaryl chloride, and succinyl chloride. The chalcone diol was synthesized by acid catalyzed Claisen-Schmidt reaction. Results and Discussions: These copolyesters were characterized by qualitative solubility tests and viscosity measurements. The microstructure of the repeating units available in the copolyester main chain was established by Fourier transform infrared, 1 H-nuclear magnetic resonance (NMR), and 13 C-NMR spectroscopic techniques. DSC was apply to study thermal analysis. The well diffusion method was employed to establish the biological efficacy of these eight copolyesters by involving Grampositive and Gram-negative bacteria. Conclusion: The presented work reports random copolyester preparation by polycondensation method and viscosity measurements tells about that the prepared compounds are of high molecular weight. others like FTIR, NMR, Solubility measurements and DSC characterize them. Biological properties was also studied.

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Neighboring group participation in cyclodehydration. A regiospecific isoxazole synthesis

Abstract: The regiospecific synthesis of isoxazoles 2, 11, 14, and 15 is explained in terms of neighboring group participation of the ortho nitrogen of the heterocyclic ring in the cyclodehydration step.

Cited by 15 publications

References 2 publications

Arylidene Derivatives as Synthons in Heterocyclic Synthesis

Arylidene Derivatives as Synthons in Heterocyclic Synthesis

Green Synthesis of Chalcone Derivatives Using Chalcones as Precursor

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