Preparation of 2-Thiazolecarboxylic Acids.

Iversen, Palle E.; Gronowitz, Salo; Dahlquist, Kjell-Ivar; Hägen, G.; Paasiv́irta, Jaakko

doi:10.3891/acta.chem.scand.22-0694

Cited by 11 publications

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“…Indications of thermal decomposition of TCA − into thiazole and CO 2 were observed in the mid-IR spectra of matrixes obtained by codeposition of Ar (or N 2 ) and vapor of TCA sublimating at 295 or 305 K. The characteristic bands due to the antisymmetric stretching and bending modes of the CO 2 molecule were detected at 2355–2330 and 665–660 cm –1 (Figure S1 in the Supporting Information). In addition, a set of much weaker mid-IR bands not originating from TCA was observed in the spectra of the matrixes (Figure and Table ).…”

Section: Resultsmentioning

confidence: 96%

Conformational Changes in Thiazole-2-carboxylic Acid Selectively Induced by Excitation with Narrowband Near-IR and UV Light

et al. 2016

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Conformers and photoinduced conformational transformations were studied for monomers of thiazole-2-carboxylic acid (TCA). The matrix-isolation technique and excitations with narrowband near-IR and UV light, tuned in an optical parametric oscillator, were used for this purpose. Form I, with the carboxylic moiety in the trans orientation and with the hydrogen atom of the OH group directed toward the nitrogen atom of the ring, was the most abundant in low-temperature argon or nitrogen matrixes. Conformer II, differing from I by 180° rotation of the OH group around the C-O bond, was also trapped in the matrixes, but in much smaller amount. The abundance of form II was experimentally determined as ∼6% of the total amount of TCA molecules. Selective excitation of I with narrowband near-IR laser light resulted in I → II transformation. This near-IR-induced conformational change was photoreversible: form II converted back to I upon selective excitation of II with near-IR light of different wavelength. Conformational conversions of I into II, or vice versa, were also induced in TCA monomers by narrowband UV excitations at 300 nm (for I → II transformation) and at 305 nm (for II → I transformation). A spontaneous conversion of photogenerated II into the most stable form I was observed for the compound trapped in the matrix at 15 K and kept in the dark. This process was very slow; the estimated half-life time of conformer II was longer than 50 h. Finally, TCA was shown to thermally decompose at room temperature, yielding CO2 and thiazole.

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Section: Resultsmentioning

confidence: 96%

Conformational Changes in Thiazole-2-carboxylic Acid Selectively Induced by Excitation with Narrowband Near-IR and UV Light

et al. 2016

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“…The original synthesis described in 1968 by Iversen [31] was slightly modified. A solution of freshly distilled 2-bromothiazole (9.00 g, 55 mmol) in diethyl ether (5 mL) was added quickly to a solution of nBuLi (1.6 m in hexanes, 38 mL, 60 mmol) in diethyl ether (100 mL) cooled to -78°C.…”

Section: Synthesis Of 2-htzcmentioning

confidence: 99%

Coordination Chemistry of Thiazole‐Based Ligands: New Complexes Generating 3D Hydrogen‐Bonded Architectures

et al. 2010

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The hydrothermal (solvothermal) reactions of ZnII, CoII, and CuII salts with the thiazole‐based ligands 2‐Htzc (thiazole‐2‐carboxylic acid), 4‐Htzc (thiazole‐4‐carboxylic acid), and Htzc‐py [2‐(2‐pyridyl)thiazole‐4‐carboxylic acid] led to the formation of coordination complexes with assorted geometry at the metal centers. The new complexes were characterized by conventional spectroscopic methods as well as by single‐crystal X‐ray analysis, TG–MS, and PXRD. Crystallographic studies have shown that an extended supramolecular network is generated in the solid state through the formaton of hydrogen bonds between the several polar groups present in the complex frameworks.

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“…Once again, 4-methylthiazole (9) was lithiated and carbonated to carboxylic acid 14. 18 Reaction of the corresponding acid chloride 15 proceeded simply to the anilide 16, which underwent Von Braun reaction 19 to the imidoylchloride and Stille coupling 20 to the desired through-conjugated model 17. Its UV spectrum in acetonitrile of both the neutral [λ max ) 311 nm, M ) 6250 M -1 cm -1 ; 360 nm (sh), M ) 2440 M -1 cm -1 ] and its protonated form (λ max ) 377 nm, M ) 12 600 M -1 cm -1 ) fell considerably short of that of the acryloyl intermediate on CEAS.…”

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confidence: 99%

“…To examine the UV spectroscopic behavior of such a possible conjugated π-system, a second model, N -(1-(4-methylthiazol-2-yl)allylidene)benzenamine ( 17 , Scheme ), was constructed. Once again, 4-methylthiazole ( 9 ) was lithiated and carbonated to carboxylic acid 14 . Reaction of the corresponding acid chloride 15 proceeded simply to the anilide 16 , which underwent Von Braun reaction to the imidoylchloride and Stille coupling to the desired through-conjugated model 17 .…”

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Observation of an Acryloyl−Thiamin Diphosphate Adduct in the First Step of Clavulanic Acid Biosynthesis

Merski

Townsend

2007

J. Am. Chem. Soc.

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The first committed biosynthetic step toward clavulanic acid, the clinically-important β-lactamase inhibitor, is catalyzed by the thiamin diphosphate (ThDP)-dependent enzyme N 2 -(2-carboxyethyl)arginine synthase (CEAS). This protein carries out a unique reaction among ThDPdependent processes in which a C-N bond is formed, and an electrophilic acryloyl-thiazolium intermediate of ThDP is proposed to be involved, unlike the nucleophilic enamine species typically generated by this class of enzymes. Here we present evidence for the existence of the putative acryloyl adduct, and report the unexpected observation of a long-wavelength chromophore (λ = 433 nm), which we attribute to this enzyme bound species. Chemical models were synthesized that both confirm its expected absorption (λ = 310-320 nm), and exclude selfcondensation and intramolecular imine formation with the cofactor as its cause. Circular dichroism experiments and others discount charge transfer as a likely explanation for the ~120 nm red shift of the chromophore (~25 kcal). Examples are well-known of charged molecules that exhibit significantly red-shifted UV-visible spectra compared to their neutral forms as, for example, polyene cations and dyes such as indigo and the cyanines. Rhodopsin is the classic biochemical example where the protein (opsin)-bound protonated Schiff base of retinal displays a remarkable range of red-shifted absorptions modulated by the protein environment. Similar tuning of the chromophoric behavior of the enzyme-bound CEAS acryloyl•ThDP species may be occurring.With the rise in resistance to penicillins and cephalosporins, the β-lactamase inhibitor clavulanic acid (1) has grown in importance for the treatment of bacterial infections 1 . Several mechanistically intriguing reactions take place in the biosynthesis of 1, 2 the first of which is mediated by N 2 -(2-carboxyethyl)arginine synthase (CEAS). The primary metabolites D-glyceraldehyde-3-phosphate (G3P) and L-arginine are recruited by this enzyme and reacted in a thiamine diphosphate (ThDP)-dependent internal redox process to yield N 2 -(2-carboxyethyl)arginine (6, CEA; Scheme 1). 3 The mechanism shown in Scheme 1 was proposed in accord with extensive isotopic labeling and stereochemical experiments. 3 NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript feature of this mechanism was the suggested intermediacy of an acryloyl-ThDP adduct 4. The observation of overall retention of configuration at the G3P β-carbon is consistent with a β-elimination/addition process proceeding by way of this highly electrophilic 4 partner for reaction with the incoming L-arginine. This is a unique reaction cycle among ThDPdependent enzymes where typically intermediates formed are nucleophilic rather than electrophilic, and N-C bond formation has not been seen previously.In this Communication we demonstrate the formation of the acryloyl species 4 and report the observation of an unexpectedly long-wavelength chromophore, which owes to the presence of the acryloyl inter...

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Preparation of 2-Thiazolecarboxylic Acids.

Cited by 11 publications

References 0 publications

Conformational Changes in Thiazole-2-carboxylic Acid Selectively Induced by Excitation with Narrowband Near-IR and UV Light

Conformational Changes in Thiazole-2-carboxylic Acid Selectively Induced by Excitation with Narrowband Near-IR and UV Light

Coordination Chemistry of Thiazole‐Based Ligands: New Complexes Generating 3D Hydrogen‐Bonded Architectures

Observation of an Acryloyl−Thiamin Diphosphate Adduct in the First Step of Clavulanic Acid Biosynthesis

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