Thiosemicarbazide hydrochloride

N 54.87% ndls (from eth), columns (from methanol plus eth) mp, deton at 128—-30°. Sol in aniline, warm ethanol, acetic acid, and acetic anhydr sparingly sol in chlf and carbon disulfide insol in benz. Prepn is by reacting a cold Na nitrite soln with an aq soln of thiosemicarbazide hydrochloride. The hydrochloride of the thiotriazole is also an expl 5-Amino-1,2,3t4-Thiotriazole Hydrochloride, CH2N4S+HC1 mw 138.59 N 40.43% cryst mp, deton at 96°. V sol in w Ref Beil 27,781... 

Trimethylchroman-3,4-dione (311a) reacted with semicarbazide hydrochloride in refluxing AcOH to give a mixture of pyrano-l,2,4-triazin-3-one (131) and the isomeric triazin-3-one (132) in a ratio of 45 55. Treatment of compound (311a) with thiosemicarbazide hydrochloride under analogous conditions yielded only pyrano-l,2,4-triazin-3-thione (151) <85JHC33>. 

Treatment of thiosemicarbazide hydrochloride with acetic monochloro-acetic anhydride affords 121.168 Further reaction with the anhydride gives 122, which readily cyclizes to the 6,5-fused ring system 123 [Eq. (38)].155... 

An unexpected cyclization occurs when the aminoamidine (43.3) is heated with thiosemicarbazide hydrochloride. 

Method B-. Finely powdered thiosemicarbazide hydrochloride (5.7 g, 45 mmol) was suspended in anhyd EtOH (80 mL), chloroacetone (5.4 g, 60 mmol) was added, and the mixture stirred at rt for 2 h. The hydrochloride precipitated from the pale yellow solution. Heating the mixture on a water bath at 35 °C for about 2 h increased the yield to 5.57 g (75%) mp 169 °C.40... 

The reaction of the pyrazolo[5,l-c]-l,2,4-triazine derivative (171) with thiosemicarbazide hydrochloride in acetic acid provided the tricyclic pyrazolo[5, r 3,4]-l,2,4-triazino[6,5-/]-l,3,4-thi-adiazepine (173) (83% yield), via the intermediate (172) (Scheme 31) <89JHC86l>. 

CH3KN2OS, Potassium thiocarbazate, 46B, 50 CH5NO2S, Methanesulphonamide, 31B, 32 CH6CIN3S, Thiosemicarbazide hydrochloride, 42B, 29 C2Hi,N2S2, Dithio-oxamide, 18, 654 30B, 36 C2H5NS, Thioacetamide, 24, 545... 

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). 

The reaction of imines with thiohydrazides gives 1,3,4-thiadiazole via a thioacylimidohydrazine intermediate. The imidoyl chloride 148 when treated with the IV-phenyl thiosemicarbazide 149 gave the 1,3,4-thiadiazole hydrochloride 150 (Equation 53) <2002MI1241>. 

Several routes to pyrazolo[4,3-e]-l,2,4-triazines have been reported. Thus, treatment ofpyrazolidine-4,5-dione (141) with semicarbazide hydrochloride or with thiosemicarbazide in cold ethanolic sodium carbonate afforded the corresponding carbazones (142a) or thiosemicarbazones (142b), which cyclized into pyrazolo[4,3-e]-l,2,4-triazines (143), upon treatment with potassium carbonate (Scheme 21) (84JHC923, 84JPR994). 

Further nucleophilic reagents used to cleave 2-amino-l,3,4-oxadiazoles include alcoholic potash, primary amines, hydrazine hydrate, phenylhydrazine hydrochloride, acid hydrazides, semicarbazide, thiosemicarbazide, ammonium hydrogen sulfide, and hydrochloric acid. 

Thiosermicarbazid 4-Benzoyl-l-(hydrazino-imino-methyl)- -Hydrochlorid E16a, 785 (Thiosemicarbazid + lsothiocya-nat)... 

See experimental Method A 67% (calculated for thiosemicarbazide) Method B 89% Method C 93%. h Hydrobromide. 0 Free base. d Hydrochloride. 

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). 

Compounds 98 are converted relatively easily to five-membered heterocycles. 1,2,4-Triazoles 102 are obtained in high yield by reactions of 98 with hydrazine derivatives (aryl hydrazines, semicarbazide, thiosemicarbazide, benzhy-drazide, and aminoguanidine) (Scheme 7). The corresponding reaction with hydroxylamine hydrochloride affords... 

---