Doubly thiazole orange-labeled cytidine for functional expansion of a hybridization-sensitive probe

A 2′-deoxycytidine derivative modified by two thiazole orange dyes has been designed for functional expansion of hybridization-sensitive fluorescence probes. This nucleotide was synthesized by a procedure that included protection of the cytosine amino group by di(n-butyl)formamidine formation, followed by incorporation into DNA. The fluorescence of the synthesized DNA was controlled by excitonic interaction, showing strong fluorescence upon hybridization with the target nucleic acid and effective quenching in a single-stranded state of the probe.     

Synthesis of thiazole aminophosphine oxides, aminophosphonic and aminophosphinic acids and Cu(II) binding abilities of thiazole aminophosphonic acids

A series of new aminophosphine oxides, aminophosphonic and aminophosphinic acids derived from thiazole was synthesized by addition of phosphine oxides or silylated phosphorus esters to the corresponding thiazole aldimines. The thiazole aldimines were obtained from 2-thiazole aldehyde and primary amines by a standard procedure. The corresponding phosphine oxides were obtained by alkylation of diethyl phosphite or ethyl phenylphosphinate with the appropriate Grignard reagents. The silylated phosphorus esters were prepared from trimethyl phosphite and from methyl- or phenylphosphinic ethyl ester by treatment with bromotrimethylsilane. The coordination ability towards Cu(II) ions are described for two obtained aminophosphonate ligands.     

Biosynthesis of the thiamin-thiazole in eukaryotes: identification of a thiazole tautomer intermediate

Thiamin thiazole biosynthesis in eukaryotes is still not completely understood. In this report, a late intermediate, tightly bound to the active site of the Saccharomyces cerevisiae thiazole synthase, was identified as an adenylated thiazole tautomer. The reactivity of this unusual compound was evaluated. Its identification provides an additional molecular snapshot of the complex reaction sequence catalyzed by the eukaryotic thiazole synthase and identifies the final step of the thiamin-thiazole biosynthesis.     

Synthesis of monothiooxamides of the thiazole series

A convenient method for the synthesis of previously inaccessible monothiooxamides of the thiazole series was developed. The method is based on the reaction of pyridinium salts obtained from 2-(chloroacetylamino)thiazole and pyridine with a solution of elemental sulfur and amines prepared beforehand.     

Residue and dissipation of zinc thiazole in tobacco field ecosystem

A high-performance liquid chromatography with ultraviolet (HPLC-UV) detection method after derivatisation was developed for the first time for the novel fungicide zinc thiazole residue in tobacco samples. Field trials in two different locations were conducted to investigate the dissipation and residue of zinc thiazole in tobacco leaves and soil. The average recoveries of zinc thiazole were in the range of 82.5%–93.9% with relative standard deviations (RSDs) of 1.2%–9.1%. The zinc thiazole showed a rapid dissipation rate in fresh tobacco leaves with the half-lives of 1.1–1.6 days. The terminal residues of zinc thiazole in cured tobacco leaves and soil were 2.8–28.0 mg kg^?1and <0.05 mg kg^?1, respectively. The results could be used to establish the maximum residue limits (MRLs) and provide guidance for the scientific use of zinc thiazole in agriculture.     

Polymethine dyes — Indolo[3,2-d]thiazole derivatives

New polymethine dyes with an indolo[3,2-d]thiazole residue are described, and their spectral properties are discussed. Replacement of the vinylene group in the naphtho[1,2-d]thiazole residue by an NH group leads to a considerably greater bathochromic shift of the absorption maximum of carbo- and merocyanines as compared with replacement by a sulfur atom. The basicity of the indolo[3,2-d]thiazole residue is higher than the basicity of the naphtho[1,2-d]-thiazole and thionaphtheno[3,2-d]thiazole residues.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1606–1610, December, 1972.     

An ab initio study of the proton affinities of some heteroatomic rings: Imidazole,oxazole, and thiazole

The proton affinities of imidazole, oxazole, and thiazole rings, relevant to the binding of lexitropsins that contain these rings to the minor groove of DNA, are calculated using ab initio (Hartree–Fock) calculations. It is found that the proton affinities decrease in the order imidazole, oxazole, thiazole and that a methyl group substituent increases the proton affinity of imidazole, while a peptidic group decreases it.     

A retrospect on antimicrobial potential of thiazole scaffold

Due to its appreciable diversity in biological actions, thiazole and its substituted components, a significant class of heterocyclic compounds has developed as an influential scaffold in the field of chemical sciences. The variability of thiazole core has been expressed through the effective instigation of its anticancer (Dasatinib, Tiazofurin), antiretroviral (Ritonavir, Brecanavir), antimicrobial (Sulfathiazole, Ravuconazole) and anti-inflammatory (Fenclozic acid, Meloxicam) derivatives. This reasonable diversity in the physiological reaction pattern led many scientists to refine and develop new structural alternatives with much more efficient pharmacological action. This review is crucial for previous studies and projects to survey the antimicrobial activity of thiazole and thiazole related compounds to the mid of 2019.     

Fluorescent properties of oligonucleotide-conjugated thiazole orange probes

The fluorescence properties of thiazole orange, linked via a (1) hydrophobic alkyl or a (2) hydrophilic ethylene glycol chain to the central internucleotidic phosphate group of a pentadeca-2'-deoxyriboadenylate (dA15), are evaluated. Linkage at the phosphate group yields two stereoisomers, S-isomer of the phosphorus chiral center (Sp) and R-isomer of the phosphorus chiral center (Rp); these are studied separately. The character of the linkage chain and the chirality of the internucleotidic phosphate linkage site influence the fluorescent properties of these thiazole orange-oligonucleotide conjugates (TO-probes). Quantum yields of fluorescence (phifl) of between 0.04 and 0.07 were determined for the single-stranded conjugates. The fluorescence yield increased by up to five times upon hybridization with the complementary sequence (d5'[CACT15CAC3']); (phifl values of between 0.06-0.35 were determined for the double-stranded conjugates. The phifl value (0.17) of thiazole orange, 1-(N,N'-trimethylaminopropyl)-4-[3-methyl-2,3-dihydro-(benzo-1,3-thiazole)-2-methylidene]-quinolinium iodide (TO-Pro 1) in the presence of the oligonucleotide duplex (TO-Pro 1: dA15.d5'[CACT15CAC3'] (1:1)) is much less than that for some of the hybrids of the conjugates. Our studies, using steady-state and time-resolved fluorescence experiments, show that a number of discrete fluorescent association species between the thiazole orange and the helix are formed. Time-resolved studies on the four double-stranded TO-probes revealed that the fluorescent oligonucleotide-thiazole orange complexes are common, only the distribution of the species varies with the character of the chain and the chirality at the internucleotidic phosphate site. Those TO-probes in which the isomeric structure of the phosphate-chain linkage is Rp, and therefore such that the fluorophore is directed toward the minor groove, have higher phifl values than the Sp isomer. Of the systems studied, thiazole orange linked by an alkyl chain to the internucleotidic phosphate (Rp isomer) has the highest phifl and the greatest fraction of the longest-lived fluorescent thiazole orange species (in the hybrid form).     

Synthesis of thiazole derivatives XXIII. 2-Methylbenzimidazoles with thiazole,benzothiazole, and quinoline groups as substituents

Derivatives of 1-phenyl-2-methylbenzimidazole, with nitrogen heterocycle groups thiazole, 4-substituted thiazole, benzothiazole, and quinoline, at position 5, are synthesized. The ethiodides of the new bases are used to prepare cyanine dyes: imidadimethinemero-, imidacarbo-, and, imidadicarbocyanines.     

Synthesis of thiazole derivatives XXIII. 2-Methylbenzimidazoles with thiazole, benzothiazole, and quinoline groups as substituents

Derivatives of 1-phenyl-2-methylbenzimidazole, with nitrogen heterocycle groups thiazole, 4-substituted thiazole, benzothiazole, and quinoline, at position 5, are synthesized. The ethiodides of the new bases are used to prepare cyanine dyes: imidadimethinemero-, imidacarbo-, and, imidadicarbocyanines.For part XXII see [1].     

Practical synthesis of a highly functionalized thiazole ketone

Compound 1 is a uniquely substituted ketone prepared via addition of a thiazole anion to an aromatic nitrile in good overall yield. An exploration into the generality of the addition of thiazole anions to nitriles allowed us to make a variety of thiazole ketones in good to excellent yields. The non-odorous thiolate-mediated demethylation reaction used in the synthesis of 1 is also presented.     

Tethered thiazole orange intercalating dye for development of fibre-optic nucleic acid biosensors

Single-stranded DNA (ssDNA) oligonucleotide in solution, or that is immobilized onto a surface to create a biosensor, can be used as a selective probe to bind to a complementary single-stranded sequence. Fluorescence enhancement of thiazole orange (TO) occurs when the dye intercalates into double-stranded DNA (dsDNA). TO dye has been covalently attached to probe oligonucleotides (homopolymer and mixed base 10mer and 20mer) through the 5′ terminal phosphate group using polyethylene glycol linker. The tethered TO dye was able to intercalate when dsDNA formed in solution, and also at fused silica surfaces using immobilized ssDNA. The results indicated the potential for development of a self-contained biosensor where the fluorescent label was available as part of the immobilized oligonucleotide probe chemistry. The approach was shown to be able to operate in a reversible manner for multiple cycles of detection of targeted DNA sequences.     

A missing enzyme in thiamin thiazole biosynthesis: identification of TenI as a thiazole tautomerase

In many bacteria tenI is found clustered with genes involved in thiamin thiazole biosynthesis. However, while TenI shows high sequence similarity with thiamin phosphate synthase, the purified protein has no thiamin phosphate synthase activity, and the role of this enzyme in thiamin biosynthesis remains unknown. In this contribution, we identify the function of TenI as a thiazole tautomerase, describe the structure of the enzyme complexed with its reaction product, identify the substrates phosphate and histidine 122 as the acid/base residues involved in catalysis, and propose a mechanism for the reaction. The identification of the function of TenI completes the identification of all of the enzymes needed for thiamin biosynthesis by the major bacterial pathway.     

Novel methods to functionalize thiazolo[4,5-c]pyridines

Novel substituted thiazole[4,5-c]pyridines have been synthesized in good yields from unsubstituted thiazole[4,5-c]pyridine using direct C-H coupling reactions and N-oxide rearrangement chemistry.     

Reactions of a 4-(trifluoromethyl)thiazole dianion

Treatment of 2-trifluoroacetamido-4-(trifluoromethyl)thiazole with two equivalents of n-butyllithium at -78° produced the thiazole dianion 5 in situ, which reacted preferentially at the 5-position with a variety of electrophiles. These electrophiles include: an aldehyde, ketone, chloroformate, acid chloride, phosphorus oxychloride, silicon chloride, and disulfide. Dianion 5 also combined with dibromodifluoromethane at -98° to give the corresponding 5-(bromodifluoromethyl)thiazole 7 , which is an unusual reaction for an aromatic or heteroaromatic system. Compound 7 was converted to a 4,5-bis-(trifluoromethyl)thiazole 8 using tetrabutylammonium fluoride.     

A universal, photocleavable DNA base: nitropiperonyl 2'-deoxyriboside

A universal, photochemically cleavable DNA base analogue would add desirable versatility to a number of methods in molecular biology. A novel C-nucleoside, nitropiperonyl deoxyriboside (NPdR, P), has been investigated for this purpose. NPdR can be converted to its 5'-DMTr-3'-CE-phosphoramidite and was incorporated into pentacosanucleotides by conventional synthesis techniques. The destabilizing effect on hybrid formation with a complementary strand when this P base opposes A, T, and G was found to be 3-5 kcal/mol, but 9 kcal/mol when it opposes C. Brief irradiation (lambda > 360 nm, 20 min) of DNA containing the P base and piperidine treatment causes strand cleavage giving the 3'- and 5'-phosphates. Two significant recent interests, universal/non-hydrogen-bonding base analogues and photochemical backbone cleavage, have thus been combined in a single molecule that serves as a light-based DNA scissors.     

噻唑类化合物应用研究新进展

噻唑环是一类重要的含氮硫杂原子的五元芳杂环,其特殊的结构使得噻唑类化合物在化学、药学、生物学和材料科学等诸多领域具有广阔的应用前景,显示出巨大的开发价值,受到广泛关注.本文结合作者的研究工作,参考国内外近五年文献,系统地综述了噻唑类化合物在医药、农药、材料、生物染色剂和超分子化学领域应用研究进展.     

Diastereoisomeric dinuclear ruthenium complexes of 2,5-di(2-pyridyl)thiazolo[5,4-d]thiazole

The first metal complexes of 2,5-di(2-pyridyl)thiazolo[5,4-d]thiazole (5) are described. X-Ray crystal structures are reported for the free ligand 5, a dinuclear copper complex 6 and the two diastereoisomers, 7meso and 7rac, of the dinuclear bis(2,2'-bipyridine)ruthenium complex. The two diastereoisomers of 7 and the 4,4'-dimethyl-2,2'-bipyridine analogue 8 are readily separated by cation exchange chromatography. 1H NMR and visible absorption spectra and electrochemical data for the four dinuclear ruthenium complexes reveal that these have relatively small HOMO-LUMO energy gaps and exhibit relatively weak metal-metal interactions.