3-Hydrazino-5/7- triazino

Condensation of 165 with ethoxymethylenemalononitrile gave 171, and with ethyl ethoxymethylenecyanoacetate or methyl bis(methylmercapto)-methylene cyanoacetate it yielded 172 (80AP108). The reaction of 172 with urea, thiourea, and benzyl nitrile afforded 173 (91PHA98). Treatment of hydrazino derivatives 165 with alkyl, aryl, or aralkyl isothiocyanates yielded (86JHC1731) 3-(/V-substituted-thiocarbamoyl)-hydrazino[l,2,4]triazino[5,6-b]indoles which have been evaluated for in vitro antimicrobial activity (Scheme 36). 

Aroylation of 3-arylhydrazonoisatin with aroyl chlorides gave 1043, which cyclized with ammonium acetate to give [1,2,4]triazino[5,6-A>]indole 1044 (92MI1). Derivatives of 1045 were prepared (92MI1). Cyclocondensation of 5-ethyl-3-hydrazino-5/f[l,2,4]triazino[5,6-b]indole 165 with succinic anhydride in acetic acid gave pyridazinedione derivative 1046 (90MI7) (Scheme 197). 

Benzoyl-l-ethoxycarbonylethylidene)hydrazino]-2(l//)-quinoxalinone (284) gave 2-phenacyl- //-[ 1,2,4]triazino[4,3-a]quinoxaline-1,5(6/f)-dione (285)... 

Hydrazino-l,2,4-triazolo[3,4-/)]benzothiazole 98 is obtained by heating 3-chloro-l,2,4-triazino[3,4-3]benzothiazole4(//)-one 481 (Equation 114) <2005IJC(B)625>. 

The reaction of 1,2,4-triazino[5,6-/>]indole-3-thione (93a X= SH) with tetracyanoethylene affords, as one of three products, the thiazolotriazinoindole (94). The 3-hydrazino compound (93b X= NHNH,) gives the triazolotriazinoindole (95) and triazepinotriazinoindole (96) [94T9997],... 

A series of l,2,4-triazino[5,6-c]quinolines have been prepared via a common route. Thus, 4-[fi-(ethoxymethylene)hydrazino]-3-nitroquinoline (244), prepared from 4-hydrazino-3-nitroquinoline (243) by reaction with triethyl orthoformate, was hydrogenated in ethanol over a palladium catalyst to give the dihydro compound (184) (96%). Dehydrogenation yielded the desired compound (185) (90%) (Scheme 19) <73GEP(0)2322394>. 

Substituted 6-chloropyrimidino[4,5-e][l,3,4]thiadiazine reacted with hydrazine hydrate to give the corresponding 6-hydrazino derivative which was transformed into various substituted [ 1,2,4]triazino[ 1,2-o]pyrimido[4,5-e][ 1,3,5]thiadiazines <05PS2477>. 

The triazine unit is the most frequently used building block for the syntheses of different condensed triazino heterocycles and the commonly used triazines for this purpose were either hydrazino- or aminotriazines. 

Hydrazone 69 (R = H) derived from 3-hydrazino-5//-l,2,4-triazino[5,6-6]indole (67, R = H) and aldose monosaccharides (68) produced the acyclo C-nucleoside (70, R = H) upon oxidative cyclization with iron(III) chloride (92BCJ546). The poly-O-acetyl derivatives of the 10-methyl and 10-ethyl congeners (70, R = Me or Et) were obtained in one step from the corresponding hydrazones (69, R = Me or Et) by cyclization with a mixture of bromine in acetic acid, anhydrous sodium acetate, and acetic anhydride (97UP1) (Scheme 22). 

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