Thiosemicarbazide pyrazoles

Cyclocondensation of pyrazole-dione 348 with thiosemicarbazide in the presence of potassium carbonate gave (84JPR994) pyrazolotriazine thione... 

Cyclodesulfurization of thiosemicarbazides, containing pyrazole <2002PS67> or benzofuran <2002PS863, 2004PS1577> units, by yellow mercuric oxide or by l,3-dibromo-5,5-dimethylhydantoin in the presence of potassium iodide <2006TL4889> afforded the respectively substituted oxadiazoles. 

The condensation products (1 1) of pentane-2,4-dione and 1,3-diphenyl-propane-1,3-dione with thiosemicarbazide, 4-methylthiosemicarbazide, and aminoguanidinium nitrate were formed (86KGS128 87ZOB584 90-KGS1260) as the cyclic isomers 78, which sometimes readily underwent dehydration to the corresponding pyrazoles. 

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). 

Many N-unsubstituted pyrazoles 80 can be obtained from A-allyl-A-nitrosamides 79 (Scheme 46) <1990H(30)789>. Cyclocondensation of -alkoxyvinyl trifluoromethyl ketones 81 with thiosemicarbazide under mild conditions affords 4,5-dihydro-l//-pyrazole-l-thiocarboxamides 82, which can be easily dehydrated with concomitant thiocarboxamide group hydrolysis in concentrated sulfuric acid to give N-unsubstituted pyrazoles 83 (Scheme 47) <1998JFC(92)23>. 

Condensation reactions can be grouped into two categories. The first category involves pyrazol-3-ones with formyl, acyl, nitroso, a,jS-unsaturated oxo, 3-oxo-2-azobutyric acid ethyl ester or acetonitrile substituents at position 4 or formyl substituents at position 5 and their reaction with carbanions, heterocyclic methylcarbenium salts, primary and secondary amines, diamines, heterocyclic perchlorates, hydroxylamine, hydrazines, urea or thiosemicarbazide. The second category involves pyrazol-3-ones with amino, hydrazino, heteroaromatic amino, acetyl or acetonitiilo groups at position 4 and their reaction with aryl or heteroaromatic aldehydes or cyclic ketones. 

Fluorine-containing 2-arylhydrazone-l,2,3-diketo esters, 2-arylhydrazones of 1,2,3-triketones and 3-arylhydrazone-l,2,3,4-triketo esters may serve as key precursors to a variety of novel heterocycles and react with binucleophiles (85UK1997, 81UK325, 94ZOR1225). Thus, the 1,2,3-triketones arylhydrazones react with hydrazine hydrate, phenylhydrazine, thiosemicarbazide, and hydroxylamine hydrochloride to form the substituted pyrazoles and isoxazoline (98JFC(92)101, 98IZV673) (Scheme 53). 

Thioureido-3-Nitroguanidine (or Nitramidino-3-thiG-semicarbazide). C2H5N S03 mw 194.20 N 43.29% OB to CO2 -32.96% fine white powder mp 182—83° (violent deton). Sol in w. Prepn is by refluxii 3,5-dimethyl-l-nitroguanyl-pyrazole with thiosemicarbazide in aq ethanol. 

The ester 5 reacts with thiosemicarbazide to yield the thiazole 6, the thiadiazine 8, or the corresponding carboxylic acids, depending on the acidity of the medium, but no triazine is obtained. The covalent hydrate 7 is an intermediate in the formation of 8. Acetylation of the thiazole 6 leads to unidentified thiadiazines or pyrazoles <96KGS1266 97CA(126)89345>. 

Ethenetetracarbonitrile reacts with 1,4-disubstituted thiosemicarbazides in chlorobenzene to give 2-phenyl-l,3,4-oxadiazine 286, pyrazole 287, and 1,3,4-thiadiazoles 288 (Equation 47) <2005HAC12>. 

The Hantzsch reaction has also been incorporated in a multi-component reaction described by Rao et al. to produce 2-pyrazol 4-yl-substituted diiazole system in one step. The reaction involves a one-pot cyclization to form thiazole, pyrazolone and cyclopropane rings via the reaction of aryl bromomethylketonewith, thiosemicarbazide, and a-acetyl-y-butyro lactone in phosphorus oxychloride. 

The construction of two heterocyclic rings in one S)mthetic step has been developed for the preparation of coumarin derivatives. In this process, the thiazole ring (31 - 40) is accomplished by Flantzsch reaction monitored by fabrication of pyrazole by reacting a 3-(2-bromoacetyl) coumarin with thiosemicarbazide and acetylacetone at room temperature [87]. 

These include carbamates and thiosemicarbazides of Si, with Sn deiivadves of phosphate, RO2CCH2, mercapto, and dithiocarbonate and carbazate, Schiff base, N-heterocycles including pyrazoles, azobenzene, aminophenyl sulphides, and N-macrocycles, pyridine carboxylates and N-subsdtuted phenols, aminobenzoates, alkoxides, esters and salicylates, sulphur and nitrogoi subsdmted carboxylic acids, amino acids, steroids and lead-soine complexes. ... 

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