C- -Heteroarylhydrazonoyl halides

Similarly, C-heteroarylhydrazonoyl halides 28a, 29, and 30e react with /3-diketones such as acetylacetone and dibenzoylmethane to give the cor-... 

Secondary amines such as morpholine reacted with 7V-heteroaryl- (11a, 12, and 15) and C-heteroarylhydrazonoyl halides (28a and 30e) to give the corresponding amidrazones 263a-c, 264, and 265, respectively [72-JCS(P1)269 73JCS(P2)1466 74JCS(P2)997 880PP521, 88PS(39)45]. 

The reaction of C-heteroarylhydrazonoyl halides with potassium cyanide is straightforward, leading in all cases to the corresponding substitution products. For example, the halides 28 and 30e yielded the cyanohydra-zones 323a and b, respectively, upon treatment with potassium cyanide in ethanol at room temperature [88H695, 88PS(39)45]. 

Both C- and N-heteroarylhydrazonoyl halides 2 and 3 yield the corresponding nitrilimines 193 and 194, respectively, when treated with a base in an aprotic solvent. When the latter 1,3-dipoles are generated in the presence of a suitable dipolarophile, they cycloadd and afford the corresponding cycloadducts. In all cases these cycloaddition reactions proved to be regioselective and stereospecific (84MI1). 

For example, /3-keto esters and /3-keto anilides react with both C-heteroaryl- and JV-heteroarylhydrazonoyl halides 5a,d,f and 28a to yield pyrazole derivatives 225-227 (77HCA2171 80JHC209 87JHC1665 88H695). 

C-Heteroaryl- and 7V-heteroarylhydrazonoyl halides react with cya-noacetic acid derivatives to yield the corresponding 5-aminopyrazole derivatives. For example, reactions of C-(2-thienyl)-N-arylhydrazonoyl halide 28a with ethyl cyanoacetate and cyanoacetanilide yielded the 5-aminopyrazole derivatives 234a and b, respectively (88H695). 

Also, reactions of thiourea with /V-heteroarylhydrazonoyl halides were also reported to give different products depending on the nature of the APheteroaryl moiety. For example, while C-aroyl-AL(2-benzimidazolyl)-hydrazonoyl halide 21a reacted with thiourea to give the expected 2-amino-... 

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