Tag: M.W=50-100

Yeh, Herman J. C. published the artcileFluorine-19 and proton nuclear magnetic resonance studies of ring-fluorinated imidazoles and histidines, Safety of 5-Fluoro-1H-imidazole, the main research area is imidazole fluoro NMR ionization; histidine fluoro NMR ionization; NMR fluoroimidazole fluorohistidine ionization.

1H and 19F titration curves in D2O and H2O, resp., were obtained for 2- and 4-fluoroimidazole and -histidine. Dissociation pK values were determined by computer-assisted curve fitting. Fluoroimidazoles are weaker bases and stronger acids than bromoimidazoles showing that the inductive effect of the halogen overshadows its resonance effect. Introduction of an alkyl group at C-5 displaces the F-4 and F-2 signals upfield and downfield, resp., indicating C-4 and C-5 are coupled by induction and resonance whereas C-2 and C-5 are coupled by induction only. Introduction of F displaces the H-2 and H-4 signals upfield. The shielding effect of the magnetic anisotropy of 19F counteracts the deshielding effect of its electronegativity. Protonation of the imidazole ring displaces the F-2 and F-4 signals downfield and upfield, resp., the same effect was observed in the imidazole anion. The amino acid side chain charge caused field perturbation of the 19F signal in fluorohistidines.

Journal of the Chemical Society, Perkin Transactions 4: Physical Organic Chemistry published new progress about Ionization. 30086-17-0 belongs to class imidazoles-derivatives, name is 5-Fluoro-1H-imidazole, and the molecular formula is C3H3FN2, Safety of 5-Fluoro-1H-imidazole.

Referemce:
Imidazole – Wikipedia,
Imidazole | C3H4N2 – PubChem

Robinson, Henry published the artcileLate-Stage Functionalization by Chan-Lam Amination: Rapid Access to Potent and Selective Integrin Inhibitors, Synthetic Route of 30086-17-0, the main research area is naphthyridinylpentanamide arylpropanoic acid boronate Chan Lam amination; aminophenylpropanoic tetrahydro naphthyridinylpentanamide preparation integrin inhibitor idiopathic pulmonary fibrosis; C−N coupling; integrin antagonists; late-stage functionalization; medicinal chemistry; β-amino acids.

A late-stage functionalization of the aromatic ring in amino acid derivatives was described. The key step was a copper-catalyzed diversification of a boronate ester I (X = 4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl; R1 = Boc; R2 = t-Bu) by amination (Chan-Lam reaction) that can be carried out on a complex β-aryl-β-amino acid scaffold. This not only considerably extended the substrate scope of amination partners, but also delivered an array of potent and selective integrin inhibitors I (X = 1-pyrazolyl, 4-chloro-1-imidazolyl, 1-piperidinyl, 1,4-oxazepan-4-yl, etc.; R1 = R2 = H) as potential treatment agents of idiopathic pulmonary fibrosis (IPF). This versatile chem. strategy, which was amenable to high-throughput-array protocols, allows the installation of pharmaceutically valuable heteroaromatic fragments at a late stage by direct coupling to NH heterocycles, leading to compounds with drug-like attributed.

Chemistry – A European Journal published new progress about Amination. 30086-17-0 belongs to class imidazoles-derivatives, name is 5-Fluoro-1H-imidazole, and the molecular formula is C3H3FN2, Synthetic Route of 30086-17-0.

Referemce:
Imidazole – Wikipedia,
Imidazole | C3H4N2 – PubChem

Catalan, Javier published the artcileThe azoles: a theoretical study, Application In Synthesis of 30086-17-0, the main research area is MO azole; protonation azole; dipole moment azole; tautomerism azole.

Ab initio calculations were reported for 35 azoles (neutral mols. and protonated azolium salts) based on INDO optimized geometries. Calculated dipole moments agreed with measured values. Protonation sites (most basic N atoms) were determined from calculated protonation energies and N lone pair changes. Linear relations between exptl. aqueous basicity and calculated protonation energies for N-methylazoles and between exptl. aqueous acidity for N-unsubstituted azoles and the charge of the NH H atom, were observed Tautomerism of the triazoles and tetrazoles were discussed.

Chemica Scripta published new progress about Acidity. 30086-17-0 belongs to class imidazoles-derivatives, name is 5-Fluoro-1H-imidazole, and the molecular formula is C3H3FN2, Application In Synthesis of 30086-17-0.

Referemce:
Imidazole – Wikipedia,
Imidazole | C3H4N2 – PubChem

Takeuchi, Y. published the artcileAcid-catalyzed isotope exchange of ring hydrogens in fluoroimidazoles, Application In Synthesis of 30086-17-0, the main research area is fluoroimidazole exchange ring hydrogen; mechanism hydrogen exchange fluoroimidazole; imidazole fluoro hydrogen exchange.

An alternative mechanism (E’) to electrophilic attack on the imidazolium ion (E pathway) involving electrophilic attack at C-(4) or C-(5) in the neutral mol., was demonstrated for imidazoles which have low pK values and which have one or two substituents capable of stabilizing a carbonium ion. Exchange by the E’ pathway occurs far more readily than E exchange. Thus, in 0.1-3 N DCl at 50°, t1/2 ≃ 9 h for 4-fluoro-2-methyl-, 12 h for 4-fluoro-1-Me, 16 h for 2-fluoro-4-methyl-, and 54h for 4-fluoroimidazole. Under these conditions, no exchange is observed at C-(2). The fluorine substituent provides the necessary combination of electronegativity and resonance overlap to permit facile exchange by the E’ pathway.

Journal of Organic Chemistry published new progress about fluoroimidazole exchange ring hydrogen; mechanism hydrogen exchange fluoroimidazole; imidazole fluoro hydrogen exchange. 30086-17-0 belongs to class imidazoles-derivatives, name is 5-Fluoro-1H-imidazole, and the molecular formula is C3H3FN2, Application In Synthesis of 30086-17-0.

Referemce:
Imidazole – Wikipedia,
Imidazole | C3H4N2 – PubChem

Kirk, Kenneth L. published the artcilePhotochemistry of diazonium salts. I. Synthesis of 4-fluoroimidazoles, 4-fluorohistamine, and 4-fluorohistidine, Related Products of imidazoles-derivatives, the main research area is photochem diazonium salt; fluorinated imidazole.

Imidazolediazonium ions, prepared by diazotization of aminoimidazoles in HBF4 and irradiated in situ, decompose with formation of fluoroimidazoles in 30-40% yield. 2-Fluoroimidazole, 4-fluoroimidazole, and Et 4-fluoroimidazole-5-carboxylate (I) were prepared I was the starting point for various transformations, including the synthesis of 4-fluorohistamine and 4-fluorohistidine. The fluorinated amino acid parallels histidine as a substrate for several enzymes and, in the case of histidine-ammonia lyase, serves as a competitive inhibitor.

Journal of the American Chemical Society published new progress about photochem diazonium salt; fluorinated imidazole. 30086-17-0 belongs to class imidazoles-derivatives, name is 5-Fluoro-1H-imidazole, and the molecular formula is C3H3FN2, Related Products of imidazoles-derivatives.

Referemce:
Imidazole – Wikipedia,
Imidazole | C3H4N2 – PubChem

Chermahini, Alireza Najafi published the artcileRelation between the substituent effect and aromaticity in imidazole derivatives: A comparative study, Application of 5-Fluoro-1H-imidazole, the main research area is aromaticity imidazole derivative.

The energies and aromaticity of R substituted imidazoles [R = NH2, OH, H, CH3, F, Cl, CN, NO, NO2], their anions and protonated forms in the gas phase were calculated with the DFT/B3LYP and MP2 methods at the 6-311++G(d,p) level. The authors analyzed the change of local aromaticity using several aromaticity indicators (Pozharsky Index, HOMA, NICS, ASE and pEDA) and found a considerable ring aromaticity for imidazoles, imidazolate anions and their protonated forms. In each class anion forms have the most aromaticity and in neutral forms, 1-H imidazoles have less aromaticity character. The HOMA and structural AI show good correlation with each other but NICS (0) values showed a poor correlation with other scales. The geometrical indexes seem to be better correlate with substituent effect.

Computational & Theoretical Chemistry published new progress about Aromaticity. 30086-17-0 belongs to class imidazoles-derivatives, name is 5-Fluoro-1H-imidazole, and the molecular formula is C3H3FN2, Application of 5-Fluoro-1H-imidazole.

Referemce:
Imidazole – Wikipedia,
Imidazole | C3H4N2 – PubChem

Hayakawa, Yoshio published the artcileSyntheses of (trifluoromethyl)imidazoles with additional electronegative substituents. An approach to receptor-activated affinity labels, Computed Properties of 30086-17-0, the main research area is imidazole trifluoromethyl preparation herbicide insecticide; affinity label preparation trifluoromethylimidazole.

Electrophilic substitution in 2- and 4-(trifluoromethyl)imidazoles provides derivatives containing one or two nitro, chloro, bromo, or iodo groups. Fluoro and chloro derivatives were also prepared by photochem. trifluoromethylation of the resp. haloimidazole. The results demonstrate that (trifluoromethyl)imidazoles behave fairly typically under the conditions of electrophilic nitration and halogenation. Of the alternative routes to the desired bifunctional and trifunctional imidazoles, electrophilic substitution on the preformed (trifluoromethyl)imidazole appears to be the method of choice in most cases. A large number of the products show herbicidal or insecticidal activity.

Journal of Organic Chemistry published new progress about Herbicides. 30086-17-0 belongs to class imidazoles-derivatives, name is 5-Fluoro-1H-imidazole, and the molecular formula is C3H3FN2, Computed Properties of 30086-17-0.

Referemce:
Imidazole – Wikipedia,
Imidazole | C3H4N2 – PubChem

Morishima, Isao published the artcileProton NMR study of hemoproteins. Ionization and orientation of iron-bound imidazole in methemoglobin and metmyoglobin, Application of 5-Fluoro-1H-imidazole, the main research area is methemoprotein imidazolyl ionization orientation; imidazolylmethemoprotein ligand ionization orientation; imidazolylmetHb ionization heme orientation; imidazolylmetmyoglobin ionization heme orientation; heme orientation imidazolylmethemoprotein ligand.

Characteristics of imidazole derivatives bound to metHb and metmyoglobin (MetMb) were investigated by H NMR spectroscopy with special regard to the ionization of the imino proton and orientation of the imidazole ring in the heme crevice. The hyperfine-shifted heme Me resonances of MetMb complexes with imidazole, 4-methylimidazole, and triazole were pH dependent, whereas those of the N-methylimidazole complex were pH independent. The pH-dependent shifts in the former complexes were attributed to the deprotonation of the imino proton of imidazole derivatives bound to the heme Fe. In contrast, MetMb complexes with 4-nitroimidazole and 4-fluoroimidazole, both of which have the ionizable NH proton, did not exhibit such pH-dependent shifts, indicating restricted orientation of the Fe-bound 4-nitroimidazole and 4-fluoroimidazole in the heme crevice, where the imino proton is not exposed to the solvent sphere. In the MetMb-imidazole complex, however, pH dependence of the hyperfine shifts was observed, in contrast to the case of imidazole-MetMb. This was also interpreted as arising from the specific orientation of the Fe-bound exogenous imidazole in the MetMb heme pocket. Two sets of heme Me proton resonances were detected for the 4-fluoroimidazole-MetMb complex and these were attributed to the 2 tautomeric forms of the Fe-bound 4-fluoroimidazole. The relative proportion of the 2 tautomers was dependent on both pH and temperature The temperature dependence of the hyperfine shifts of the 2 species indicated that they are in a single spin state.

Biochimica et Biophysica Acta, Protein Structure published new progress about Ionization. 30086-17-0 belongs to class imidazoles-derivatives, name is 5-Fluoro-1H-imidazole, and the molecular formula is C3H3FN2, Application of 5-Fluoro-1H-imidazole.

Referemce:
Imidazole – Wikipedia,
Imidazole | C3H4N2 – PubChem

Dolensky, Bohumil published the artcileSynthesis of 4,5-difluoroimidazole, Formula: C3H3FN2, the main research area is imidazole difluoro preparation; photochem Schiemann reaction aminoimidazole fluorination.

5-Fluoroimidazole-4-carboxylic acid Et ester 3 was converted to the corresponding hydrazide 4 in 81% yield. Oxidation of the hydrazide to the carbonyl azide 5 (88%) and Curtius rearrangement in t-Bu alc. produced 94% 4-t-butyloxycarbonylamino-5-fluoroimidazole 6. Dissolution of the t-Bu carbamate in 50% HBF4, in situ diazotization of the resulting amine, and irradiation produced the target compound 1 in 36% yield from 6 by the photochem. Schiemann reaction.

Journal of Fluorine Chemistry published new progress about Curtius reaction. 30086-17-0 belongs to class imidazoles-derivatives, name is 5-Fluoro-1H-imidazole, and the molecular formula is C3H3FN2, Formula: C3H3FN2.

Referemce:
Imidazole – Wikipedia,
Imidazole | C3H4N2 – PubChem

Catalan, Javier published the artcileSubstituent effects on proton affinities: through bonds or through space mechanism?, Product Details of C3H3FN2, the main research area is MO pyrazole imidazole; protonation energy pyrazole imidazole; lone pair orbital energy heterocycle.

INDO calculations of the protonation energies and lone pair orbital energies of twenty pyrazoles and twenty imidazoles have been carried out in order to ascertain the mechanism of the substituent effect; Me, cyano, fluoro, amino, and nitro substituents have been examined The nitro group shows a special behavior. The importance of optimizing the geometry and the reasons for the anomaly shown by the nitro derivatives are discussed.

Heterocycles published new progress about Electronic state. 30086-17-0 belongs to class imidazoles-derivatives, name is 5-Fluoro-1H-imidazole, and the molecular formula is C3H3FN2, Product Details of C3H3FN2.

Referemce:
Imidazole – Wikipedia,
Imidazole | C3H4N2 – PubChem