5- Methyl thiosemicarbazide

Condensation of thiosemicarbazides of nicotinic and isonicotinic acids (528) and their hydrochlorides, with a-halocarbonyl compounds gave the corresponding hydrazinylthiazoles (149), in which Rj = methyl, phenyl, or aryl and R2 = H (Scheme 74). 

An alternative synthesis of this ring system involved the construction of the triazine ring at the first stage. Thus, the reaction of diethyl oxomalo-nate either with thiosemicarbazide followed by methylation or with S-... 

Acylation of thiosemicarbazides with acyl chloride 222, under standard basic conditions, gives 2-aryl-5-methyl-thia-zolo[3.2-// [ l, 2,4]triazolc-6-carbothiosemicarbazides 223, that on sodium hydroxide-promoted cyclization affords 2-aryl-5-methyl-thiazolo[3,2-4][l,2,4]triazol-6-yl)-l//-l,2,4-triazole-3-thiones224 (unreported yields) (Scheme 14) <2001FAR15>. 

Acyloin 213 with thioamides, thiosemicarbazides, and methyl dithio-carbazate in trifluoroacetic acid give photochromic thiazole-, thiadiazine-, and pyrazole-bridged dihetarylethenes 254,255, and 256-258, respectively (Scheme 72) (OlIZVllS, 06ZOR882). 

A number of mesoionic l,2,4-triazolo[4,3-a]pyrimidines (15) were obtained upon desulfurization of l-methyl-l-(4,6-dimethylpyrimidin-2-yl)thiosemicarbazides (13) with dicyclohexylcarbodiimide (DCC) [88JCS(CC)506 93JCS(P1)705] or by cyclization of l-alkyl-l-(4,6-dimethylpyrimidin-2-yl)hydrazines (14) with carbon disulfide or phosgene [88JCS(P1)351] (Scheme 8). 

Oxygen can be transferred from the arene oxides to nitrogen-, sulfur-, or phosphorus-containing substrates like pyridine, thiourea, N-methyl-benzothiazol-2-thione, thioacetamide, thiosemicarbazide, thiols, thio ethers, triphenylphosphine,21,160,161 etc. Parent hydrocarbons are formed as products.162 Thus the dimethoxycarbonyl oxide 269 on heating with pyridine produces 9,10-dimethoxycarbonylphenanthrene (270). The reaction of 1 or its... 

Another hydrazine derivative of fluorescein, 5-(((2-(Carbohydrazino)methyl)thio)-acetyl)-aminofluorescein, contains a longer spacer arm off its No. 5 carbon atom of its lower ring than fluorescein-5-thiosemicarbazide, described previously (Molecular Probes). The reagent can be used to react spontaneously with aldehyde- or ketone-containing molecules forming a hydrazone linkage (Fig. 209). It also can be used to label cytosine residues in DNA or RNA by use of the bisulfite activation procedure (Chapter 17, Section 2.1). The resulting fluorescent derivative exhibits a maximal excitation at 490 nm and a maximal luminescence emission peak at 516 nm when dissolved in buffer at pH 8. In the same buffered environment, the compound has an extinction coefficient of approximately 75,000 M-1cm 1 at 490 nm. 

Reactions of arylidenecycloalkanones with thiosemicarbazide in contrast to hydrazines usually yield cis isomers of the appropriate 7V-thiocarbamoyl derivatives of pyrazolines. For instance, treatment of 3,5-diarylidene-l-methyl-4-piperidones 80 and some other cyclic unsaturated ketones with thiosemicarbazide 81 under acidic conditions leads to dx-pyrazolines 82 in high yields [65] (Scheme 2.20). 

Use of the more expensive nitrosation reagent butylnitrite is successful when the reaction fails with the cheaper sodium nitrite reagent <2004JST23>. Introduction of a 15N label at the exocyclic nitrogen in compounds 45 where R = Me is achieved using the lsN-enriched l-phenyl-4-methyl-3-thiosemicarbazide formed from 15/V-methylamine... 

The analogous condensation of methyl acetylenedicarboxylate with substituted thiosemicarbazides leads to 2-imino-3-amino-6-carbomethoxyl-l,3-thiazin-4-ones (67CJC953). 

Cyclization in phosphorus oxychloride of semicarbazides (79 X = NHR) yields aminooxadiazoles (81) whereas thermolysis leads to loss of ammonia (when X = NH2) and formation of an oxadiazolinone (80). Cyclization to aminooxadiazoles (81) occurs when thiosemicarbazides (82) are heated with an oxidizing agent such as lead oxide. This reaction has been widely applied to the synthesis of aminooxadiazoles, sometimes in low yields, and has been used to prepare 2-amino-l,3,4-oxadiazole (81 R1 =R2 = H). 5-Methyl ethers of thiosemicarbazides (82) cyclize, with loss of methanethiol, to aminooxadiazoles (81) on heating, but in PPA cyclization to 2-methylthio-l,3,4-oxadiazoles occurs. 

Aryl tellurium trichlorides treated with the thiosemicarbazides of benzaldehydes or methyl phenyl ketones produced the thiosemicarbazonc complexes of the aryl tellurium monochlorides8. 

Bis(thiosemicarbazide)nickel(II) forms charge augmented double hydrogen-bonded chains with 1,4-terephthalate and trans-fumarate anions, which are further linked into sheets by hydrogen bonds between the N-H- -O units. The methylation of the primary amine disrupts these interactions markedly so that hydrogen-bonded sheets result, involving now molecules of water. ... 

Thiosemicarbazid 4-Hydroxy-4-methyl-1 -(5-nitro-2-furoyl)-E16a, 192 (Acylier.)... 

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