Reaction of β‐dimethylaminovinyl ketones with hydroxylamine: A simple and useful method for synthesis of 3‐ and 5‐substituted isoxazoles

Rosa, Fernanda A.; Machado, Pablo; Bonacorso, Hélio G.; Zanatta, Nilo; Martins, Marcos A. P.

doi:10.1002/jhet.5570450337

Cited by 34 publications

(15 citation statements)

References 23 publications

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“…Instead, products 3 , 4 , and 5 were identified in the reaction mixture based on IR and NMR spectroscopic evidence. The recorded spectra of 4a – c and 5a – c were consistent with those available in the literature. − To support the characterization of azirines 3a – c , we compared their 1 H NMR spectra to those reported for 2-benzoyl-2-methyl-2 H -azirine and 2-methyl-2-phenyl-2 H -azirine, in which the vinylic hydrogen atom on the azirine ring is observed at 9.75 and 9.80 ppm, respectively, corresponding to that in azirine 3 at 9.67 ppm. Similarly, the α-hydrogen atom in azirine 3 is located at 3.5 ppm, which is similar to the chemical shift observed for the α-hydrogen atom of 2-benzoyl-3-methyl-2 H -azirine at 3.50 ppm …”

Section: Results and Discussionsupporting

confidence: 67%

Cracking under Internal Pressure: Photodynamic Behavior of Vinyl Azide Crystals through N₂ Release

et al. 2020

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When exposed to UV light, single crystals of the vinyl azides 3-azido-1-phenylpropenone (1a), 3-azido-1-(4-methoxyphenyl)propenone (1b), and 3-azido-1-(4-chlorophenyl)propenone (1c) exhibit dramatic mechanical effects by cracking or bending with the release of N2. Mechanistic studies using laser flash photolysis, supported by quantum mechanical calculations, show that each of the vinyl azides degrades through a vinylnitrene intermediate. However, despite having very similar crystal packing motifs, the three compounds exhibit distinct photomechanical responses in bulk crystals. While the crystals of 1a delaminate and release gaseous N2 indiscriminately under paraffin oil, the crystals of 1b and 1c visibly expand, bend, and fracture, mainly along specific crystallographic faces, before releasing N2. The photochemical analysis suggests that the observed expansion is due to internal pressure exerted by the gaseous product in the crystal lattices of these materials. Lattice energy calculations, supported by nanoindentation experiments, show significant differences in the respective lattice energies. The calculations identify critical features in the crystal structures of 1b and 1c where elastic energy accumulates during gas release, which correspond to the direction of the observed cracks. This study highlights the hitherto untapped potential of photochemical gas release to elicit a photomechanical response and motility of photoreactive molecular crystals.

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Section: Results and Discussionsupporting

confidence: 67%

Cracking under Internal Pressure: Photodynamic Behavior of Vinyl Azide Crystals through N₂ Release

et al. 2020

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“…The other isomeric compounds 5 a,b were excluded since the isoxazole‐H5 would be expected to resonate at δ=9.25 ppm. The regioselectivity for the formation of isoxazolo[5,4‐ d ]pyrimidinones 4 a,b is in perfect agreement with the literature …”

Section: Resultssupporting

confidence: 89%

Synthesis, In Vitro Cytotoxicity and Bleomycin‐Dependent DNA Damage Evaluation of Some Heterocyclic‐Fused Pyrimidinone Derivatives

et al. 2020

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In this work, enaminones 1 a,b were used as precursors for the synthesis of novel fused heterocyclic ring systems (e. g. pyrazolo [3,4-d]pyrimidinones, isoxazolo[5,4-d]pyrimidinones, pyrimido [4,5-d]pyrimidinones and related compounds) via their reactions with some N-nucleophiles. The cytotoxic activity of the designed products was assessed via the MTT colorimetric assay against human liver hepatocellular carcinoma (HepG2) and normal lung fibroblasts (WI-38) cell lines using doxorubicin as a reference standard. Among the screened compounds, pyrazolo[3,4-d]pyrimidinone 3 d and pyrimido [4,5-d] pyrimidinones 6 a,b, 7 b and 8 a,b were selected as lead molecules because they showed significant activity against HepG2 cells and a weak cytotoxic effect against WI-38 cells. In further, all of the compounds were subjected to the bleomycin-dependent DNA damage studies. The results indicated that most of them have a remarkable ability to protect DNA compared to ascorbic acid as a standard compound.

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“…Progress in the development of new methods for the synthesis of isoxazoles has been possible owing to the abundance of the isoxazole moiety in the structures of numerous natural and synthetic compounds of vital medicinal importance . It appears that the reaction of α,β‐unsaturated carbonyl compounds that contain a hydroxylamine moiety and a leaving group is a very convenient strategy for the preparation of 3‐ or 5‐substituted isoxazoles . Thus, chloropropenal 145 reacted with hydroxylamine (1:1,1) in MeOH at 60 °C for 1 h to give 5‐(2‐naphthyl)isoxazole 147 in 66 % yield (Scheme ) .…”

Section: Oxazoles Thiazoles and Isoxazolesmentioning

confidence: 99%

Synthesis of Diheteroatomic Five‐Membered Heterocyclic Compounds from α,β‐Unsaturated Aldehydes

Keiko

Вчисло

2016

Asian J Org Chem

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The recent increasei ni nterest in the chemistry of azoles has been owing to their paramount importance in several essential fields of research, such as pharmacology, medicine, biology, the organic synthesis of fine chemicals, agriculturalc hemistry, and the chemical industry.T his Focus Review summarizes and highlights recently developed methods for the synthesis of five-membered N,N-, N,O-, andN ,Sheterocycles based on the transformations of 2-alkenals. Over the last 15 years, these reactions, which often differ from reactions involving other a,b-unsaturatedc arbonyl compoundsi nt erms of methoda nd results, have gathered significant momentum. The multitude of catalytic and tech-nological novelties discussed in this Focus Review,s uch as asymmetricm etal-and organocatalysis,o ne-pot multicomponent reactions that proceed through domino, cascade, or tandem sequences, and microwave activation,p romote the formation of ad iverse range of target products, the structures of which becomec lear from the mechanistic schemes given in this Focus Review.T he mechanisms discussed reflect great advances in the chemo-, regio-, and stereoselectivity of the reactions of 2-alkenals, which allows new azoles and related compounds (imidazoles, pyrazoles, oxazoles, thiazoles, and their hydrogenatedd erivatives) to be synthesized.[a] Prof.The ORCID identification number(s) for the author(s) of this articlecan be found under http://dx.Scheme2.One-potsynthesis of imidazoles 8 and tentativemechanism of the reaction.T s= 4-toluenesulfonyl, TMS = tert-butyltrimethylsilyl, Bn = benzyl, Lg = leaving group.Scheme3.Enantioselective synthesiso f3-hydroxyalkyl and 3-aminoalkyli midazo[1,2-a]pyridines (9)through an asymmetricorganocatalytic [3+ +2] annulation strategy.Alk = alkyl.Scheme4.One-potsynthesis of imidazole-containingc ondensed heterocycles by the reaction of 2-alkoxypropenalswith N-binucleophiles.Scheme9.Aroute to 2-(1'-alkoxyvinyl)imidazolidines 27 through the condensation of alkoxy propenals.

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Reaction of β‐dimethylaminovinyl ketones with hydroxylamine: A simple and useful method for synthesis of 3‐ and 5‐substituted isoxazoles

Abstract: -2-yl, thien-2-yl, pyrrol-2-yl, Et and CCl 3 ] and hydroxylamine hydrochloride varying only the reaction conditions (with and without the addition of pyridine) is reported.

Cited by 34 publications

References 23 publications

Cracking under Internal Pressure: Photodynamic Behavior of Vinyl Azide Crystals through N₂ Release

Cracking under Internal Pressure: Photodynamic Behavior of Vinyl Azide Crystals through N₂ Release

Synthesis, In Vitro Cytotoxicity and Bleomycin‐Dependent DNA Damage Evaluation of Some Heterocyclic‐Fused Pyrimidinone Derivatives

Synthesis of Diheteroatomic Five‐Membered Heterocyclic Compounds from α,β‐Unsaturated Aldehydes

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Reaction of β‐dimethylaminovinyl ketones with hydroxylamine: A simple and useful method for synthesis of 3‐ and 5‐substituted isoxazoles

Abstract: -2-yl, thien-2-yl, pyrrol-2-yl, Et and CCl 3 ] and hydroxylamine hydrochloride varying only the reaction conditions (with and without the addition of pyridine) is reported.

Cited by 34 publications

References 23 publications

Cracking under Internal Pressure: Photodynamic Behavior of Vinyl Azide Crystals through N2 Release

Cracking under Internal Pressure: Photodynamic Behavior of Vinyl Azide Crystals through N2 Release

Synthesis, In Vitro Cytotoxicity and Bleomycin‐Dependent DNA Damage Evaluation of Some Heterocyclic‐Fused Pyrimidinone Derivatives

Synthesis of Diheteroatomic Five‐Membered Heterocyclic Compounds from α,β‐Unsaturated Aldehydes

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Cracking under Internal Pressure: Photodynamic Behavior of Vinyl Azide Crystals through N₂ Release

Cracking under Internal Pressure: Photodynamic Behavior of Vinyl Azide Crystals through N₂ Release