2.4- Dimethylthiazole-3-oxide

Methylthiazole-3-oxide in the same conditions gave both 4-ace-toxymethylthiazole and 2-acetoxy-4-methylthiazole but in low yields. The reaction of 2,4-dimethylthiazole-3-oxide with p-tolyl chloride has also been studied (268), substitution occurring on the 2- and 4-methyl groups. 

Thiazole A-oxides may result from the direct oxidation of thiazoles with hydrogen peroxide or with tungstic acid or peracetic acid. These products are unstable and break down by autoxidation 2,4-dimethylthiazole 3-oxide rearranges in acetic anhydride into... 

Only one reaction of thiazole N-oxides has been studied in detail. The rearrangement in acetic anhydride of 2,4-dimethylthiazole-3-oxide gave 2-acetoxy-4-methylthiazole and 4-acetoxymethyl-2-methylthiazole in a ratio of about 4.5 to 1(264). 

Thiazole-N-oxides are prepared by the action at low temperature (-10°C) of hydrogen peroxide in acetic acid (474). 4-MethyIthiazole and 2,4-dimethylthiazole afforded the corresponding N-oxides with yields of 27 and 58%, respectively (Scheme 88). Thiazole-N-oxides without a methyl group in the 2-position are so unstable that they have a tendency to form 2-hydroxythiazoles and are decomposed by oxidation, whereas a 2-methyl group would prevent such rearrangement (474). 

Dye oxidation (e.g., tetrazolium reductase activity with 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide, MTT 2-[4-iodophenyl]-3-[4-nitrophenyl]-5-[2,4-disulfophenyl]-2H tetrazolium monosodium salt, WST-1 3- (4,5 -carboxymethoxyphenyl) -2-(4-sulfophenyl)-2 H-tetra-zolium, MTS 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide inner salt, XTT 2,2 -di-p-nitrophenyl-5,5 -diphenyl-3,3 -(3,3 -dimethoxy-4,4 -diphe-nylenej-ditetrazolium chloride, NET), Alamar blue assays, ATP concentration (e.g., luciferase assay), oxygen consumption (e.g., oxygen electrodes, phosphorescent oxygen-sensitive dyes), mitochondrial protein and nucleic acid synthesis mitochondrial mass (e.g., mitotracker dyes) mitochondrial membrane potential (e.g., tetramethylrho-damine methyl ester, TMRM tetramethylrhodamine ethyl ester, TMRE)... 

The oxidation of thiazoles by peroxy acids leads to the corresponding A-oxides. Peracetic, MCPBA, permaleic, and trifluoroperacetic acid have been employed for this reaction. Chemical yields range from 4% to 50%, the more basic thiazoles producing higher yields. Thus, thiazole, 2,4-dimethyl- and 4,5-dimethylthiazoles, and 2-phenylthiazole can be oxidized in moderate to good yields. However, neither 4-chloro-2-phenylthiazole nor 5-chloro-2-phenylthiazole could be oxidized. 3-Oxides were also obtained by oxidation of 1,2,3-thiadiazoles and 5-phenylthiatriazole (121—>122) (75T1783). 

Dimethylthiazole has been prepared from chloroacetone and thioacetamide,1 but forming the required thioacetamide in the reaction mixture is to be preferred since no additional manipulation is involved. The method here described is substantially that of E. Merck.2 Other substituted thiazoles can be prepared by practically the same method.2 2,4-Dimethylthiazole has been obtained by dry distillation of 2-methylthiazyl-4-acetic acid,3 and also by heating 2,4-dimethylthiazole-5-carboxylic acid with calcium oxide.4... 

Haloperidol, a dopamine receptor antagonist, was cytotoxic to mouse clonal hippocampal HT22 cells in a concentration-dependent manner and caused death by oxidative stress as assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazo-lium bromide (Post et al. 1998). The addition of haloperidol to HT22 cells led to an increase in intracellular peroxides and a rime-dependent drop in the intracellular glutathione levels. Haloperidol-induced oxidative cell death was prevented by melatonin, its precursor N-acetyl serotonin, and most effectively by a-tocopherol. 

The MTT ]3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] and LDH (lactate dehydrogenase) assays are commonly used to evaluate the cytotoxidty of nanomaterials, while measurements of ROS, glutathione (GSH) and hOggl are used to evaluate nanomaterial-induced oxidative stress. The different cell Unes... 

Studies have recently addressed the cytotoxicity of uranyl acetate in primary rat cortical neuron cultures. Researchers found no evidence that uranyl acetate at concentrations less than 100 pM caused cytotoxicity (Jiang et al., 2007 Aschner and Jiang, 2009). Furthermore, there was no significant change in the levels of F2-isoprostanes, biomarkers of oxidative stress, as well as thiol metabolite levels on treatment with uranium. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium... 

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