1H NMR Evidence of C–H---O, C–H---N and C–H---Cl Hydrogen Bonds in New Thiazole Derivatives

Sánchez‐Viesca, Francisco; Berros, Martha

doi:10.3987/com-02-9478

Cited by 15 publications

(14 citation statements)

References 2 publications

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“…[23] Such a downfield shift has been reported as a typical feature of intramolecular weak CH/N hydrogenbonding. [29] As summarized in Figure 6, the chemical shift of H1 showed a systematic upfield shift of 0.095 ppm upon heating from 293 to 353 K. Furthermore, the signal corresponding to the N-methyl protons of 1-methyl-7-azaindole in compound 1a showed an upfield shift upon heating from 293 to 353 K, which also suggests specific hydrogen-bonding at room temperature. No other signal from the 1-methyl-7-azaindole group revealed such a significant temperature dependence.…”

Section: Resultsmentioning

confidence: 84%

Intramolecular Hydrogen Bonding in a Triangular Dithiazolyl‐Azaindole for Efficient Photoreactivity in Polar and Nonpolar Solvents

2011

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A triangular dithiazolyl-azaindole derivative has been synthesized as a highly sensitive photochromic molecule. 2,4-Dimethyl-5-phenylthiazol derivative 1a, and a reference compound, 5-methyl-2-phenylthiophene derivative 2a, both showed photochromism with quantum yields of 90 and 45 %, respectively, in hexane, and 90 and 35 %, respectively, in methanol. In the single-crystal state, 1a revealed photochromic coloration. Its conformation was assigned to a photoreac-

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Section: Resultsmentioning

confidence: 84%

Intramolecular Hydrogen Bonding in a Triangular Dithiazolyl‐Azaindole for Efficient Photoreactivity in Polar and Nonpolar Solvents

2011

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“…We have found that the H-5 NMR signal in thiazole derivatives shows ringing in the spectra at 90 MHz (12). This can be accounted for by the presence of a near heteroatom (H-C-S).…”

Section: Synthesis and Speclroscop Of New 4-aryl-2(3h)-thiazolethionementioning

confidence: 94%

“…The tautomeric structure of 2-mercaptothiazole was discarded since the H-5 signal would appear at about 7.6 ppm (12,13), instead of at 6.60 ppm. The test with FeCl.i/K.iFe(CN) 6 described to detect enols and cryptophenols (14) was applied to the thiazolethione 3, in order to know if this reagent also detects the isomeric thioenol structure due to a possible prototropy in this compound.…”

Section: Synthesis and Speclroscop Of New 4-aryl-2(3h)-thiazolethionementioning

confidence: 99%

Synthesis and Spectroscopy of New 4-Aryl-2(3h)- Thiazolethiones and Derived Thiazoles

Sánchez‐Viesca¹,

Berros²

2004

Heterocyclic Communications

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The optimized preparation of four new 4-aryl-2(3W)-thiazolethiones and three new phenacylthiothiazoles is described.Since the 2(3W)-thiazolethiones contain three functional groups in their ring: an enamine, a thiolactam, and a dithiolactone. their influence was studied by alkylation/aromatization reactions and by 'H-NMR experiments on deuterium exchange with DMSOd"/D,0. CDCi,/CF,COOD, CF,COOD and CF,C00D/D 2 0. Among these new compounds we have found intramolecular weak hydrogen bonding, as well as deuterium exchange involvingThe compounds under study have been registered in Chemical Abstracts as 4-thiazoline-2-thiones from 1951 to 1971, and as 2(3H)-thiazolethiones onwards. The earlier works considered these compounds as 2-mercapto-thiazoles.The papers related to these thioxo compounds have been reviewed several times (1-8).The reaction of an α-halo ketone with a dithiocarbamate (3) to obtain a 2(3W)-thiazolethione has been employed with rather simple ketone derivatives. We have prepared four new 4-aryl-2(3//)-thiazolethiones having di-or trisubstituted phenyl groups. Results and DiscussionWe tried the reaction of 2,4.5-trimethoxyphenacyl chloride (9), 1. with ammonium dithiocarbamate (10.11). A mixture dioxaneethanol (3:5) was employed as solvent due to the low solubility of the chloride 1 in FitOH. However, instead of the expected hcterocycle, bis(2,4.5-trimethoxyphenacyl) disulfide. 2. was formed via the α-mercaptoketone and air oxidation. The IR (KBr wafer) and 'H-NMR data (CDCh. 300 MHz) are given in Οις formulas.hydrogens bound to sp~ carbon atoms.

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“…Following our study on intramolecular hydrogen bonding, deduced from 1 H Nuclear Magnetic Resonance Spectroscopy [1][2][3], we now present evidence for the existence of this type of atomic interactions in 2,3-bis-(3,4-dimethoxybenzoyl)propionitrile, 5, in solution in CDCl 3 . This compound was obtained as is described in the next section.…”

Section: Introductionmentioning

confidence: 99%

Intramolecular Hydrogen Bonding in 2,3-Bis-(3,4-dimethoxybenzoyl)Propionitrile

Sánchez‐Viesca¹,

Berros²,

Gómez³

2012

CHEMISTRY

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3,4-Dimethoxybenzoylacetonitrile, required in the synthesis of some isoxazole derivatives, was obtained from α-bromoacetoveratrone and potassium cyanide. In this reaction, a byproduct could be isolated. From its IR, 1 H-NMR, MS and elemental analysis data, it was identified as 2,3-bis-(3,4-dimethoxybenzoyl)propionitrile. A careful study of its NMR spectrum revealed the existence of two intramolecular weak hydrogen bonds, in solution in CDCl 3 , of the type C-H---O=C. Paramagnetic shifts, Δδ, of 0.5 and 1 ppm, were found for the hydrogens involved in the interactions, as well as significant differences in the coupling constants. A molecular model confirmed the findings made by the conformational analysis. Thus, the secondary structure of the title compound was established.

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1H NMR Evidence of C–H---O, C–H---N and C–H---Cl Hydrogen Bonds in New Thiazole Derivatives

Cited by 15 publications

References 2 publications

Intramolecular Hydrogen Bonding in a Triangular Dithiazolyl‐Azaindole for Efficient Photoreactivity in Polar and Nonpolar Solvents

Intramolecular Hydrogen Bonding in a Triangular Dithiazolyl‐Azaindole for Efficient Photoreactivity in Polar and Nonpolar Solvents

Synthesis and Spectroscopy of New 4-Aryl-2(3h)- Thiazolethiones and Derived Thiazoles

Intramolecular Hydrogen Bonding in 2,3-Bis-(3,4-dimethoxybenzoyl)Propionitrile

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