Hydrazonyl halides

Thioxo-l,2,4-triazin-5-ones and hydrazonyl halides react together in the presence of triethylamine in dichloromethane to yield l,2,4-triazolo[4,3-ftHl,2,4]-triazin-5-ones 81 <95M105 96CA(124)317107>. 

Refluxing hydrazonyl halide 16 with 3-amino-2-thioxo-4(l//)-quinazoline 17 under similar conditions yielded 6/7-[l,2,4,5]tetrazino[3,2- ]quinazolin-6-ones 6 (Equation 4) <2001M959>. 

Nitrilimines represent a well investigated class of 1,3-dipoles.55 Access to this group of dipoles can be realized by (i) treatment of hydrazonyl halides with base,92 (ii) thermal or photochemical decomposition... 

The l,4-diacyl-3-acylamino-5-phenyl-4,5-dihydro-1H-1,2,4-triazole (99) was generated by the ring-closure of a guanidinylhydrazone with acetic anhydride in ca. 80% yield. The structure of the triazole was confirmed by spectroscopy and x-ray analysis [95M733], The N-benzyl triazoline (100) was prepared by reaction of N-benzylidinebenzylamine with a hydrazonyl halide with K,CO, in benzene, followed by 2 eq of Et,N for 1 h, in 75% yield [95ZOB308]. 

Heterocyclic hydrazonyl halides which possess an amino-hydrogen undergo ring closure via 1,3-dipolar nitrile imines which can also be written as 1,5-dipolar ions. 1,5-Electro-cyclization then gives the fused product (Scheme 13). The method has been used for the preparation of 6,7-dihydro-3-aryl-5H-imidazo[2,l-c]-s-triazoles (72JCS(P2)1887),... 

Cycloaddition of 1,3-benzothiazines (423) to hydrazonyl halides 424 led (84H537) to the formation of examples (425) of the title compounds. 

Nitrile imines can be generated in a similar way the dehydrohalogenation of hydrazonyl halides (from A-halosuccinimide and a hydrazone), or, as in the sequence below, elimination of benzenesulfonate. ... 

Synthesis of triazolo[4,3-fl pyrimidines via reaction of hydrazonyl halides with ethyl 3,4-dihydropyrimidine-5-carboxylate derivatives has been described <04PS601>. Synthesis of perfluoroalkyl[l,2,4]triazolo[l,3]thiazinones has been reported <04JGU472>. 

Novel substituted 1,3,4-thiadiazoles (40 and 41) and bi(l,3,4-thiadiazole) (43) were synthesized from the reaction of thiocarboxanilide (37) with a series of different hydrazonyl halides (38 and 39) or N,N -diphenyl-oxalodihydrazonoyl dichloride (42) in ethanol in the presence of triethylamine under ultrasonic irradiation... 

Hydrazonyl halides, which are readily available by halogenating hydrazones, may be useful intermediates for the preparation of thiohydrazides. - Depending on the conditions, sym- and w/wym-hydrazonyl sulphides (111 X = S), or substituted 1,3,4-thiadiazolines, may be prepared. With thiophenols, thiohydrazonates (112) are obtained, which give the thiadiazines (113) when heated with ethanol. In concentrated hydrochloric acid the hydrazonates (112) are rearranged to thiohydrazides. 

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