Reaction with cyanoacetic hydrazides

The lH-l,2,4-triazole compounds possess important pharmacological activities such as antifimgal and antiviral activities [18-20]. In the present study, the reactive intermediates 45a-c, prepared in situ from the dichlorides 44a-c, were reacted via the cycloaddition reaction with ethyl cyanoacetate 40 to give, after spontaneous rearrangement, the triazole hydrazides 41a-c. These compoimds were used as starting materials for the synthesis of the... 

The Gewald synthesis of 2-aminothiophen-3-carboxylic acid derivatives has been extended to cyanoacetic acid hydrazides. In the base-catalysed reaction with cyclohexanone and sulphur, the hydrazides yielded the thienopyrimidone derivative (24), which could be hydrolysed to the 2-aminothiophen-3-carboxylic acid hydrazide (24a). A series of substituted 2-aminothiophen-3-carboxylic esters have been prepared by a... 

Reaction of 91 and 92 with 88 furnishes the arylidene products 89 [81S635 84ZN(B)824 87IJC(B)216], whereas the condensation of 92a with cyanoacetic acid hydrazide yields the parent bicyclic product 93 (84JHCI885). Arylidene product 89 is presumed to have been obtained via the intermediate 5-benzylidene derivative of 91 and 92 formed by the addition of the active methylene in 91 and 92 to the activated double bond of benzylidene malononitrile with concomitant elimination of malononi-trile, which subsequently adds to the activated double bond of the interme-... 

N-[3 -(4-Methy Iphenyl)-1 -phenyl-1 H-pyrazol-4-methylidene] -cyanoacetic acid hydrazide 154 was synthesised in an excellent yield by condensing 3-(4-methylphenyl)- -phenyl-lH-pyrazole-4-carboxaldehyde with cyano-acetic acid hydrazide. This intermediate was converted to the 4-amino-3-aryl-5-[3-(4-methylphenyl)-1 -phenyl-1 H-pyrazol-4-methylidenehydrazinocarbonyl] -thiazole-2(3H)-thiones 155 (Scheme 72), following the method described by Gewald, it involved the reaction of the cyanoacetic acid hydrazide derivative 154 with sulphur and the appropriate aryl isothiocyanate in the presence of triethylamine as a basic catalyst. Cyclisation of 145 to the 3-aryl-6-[3-(4-methylphenyl)-l-phenyl-1 H-pyrazol-4-methylideneamino] -2-thioxo-2,3 -dihydrothiazolo [4,5 -djpyrimidin-7(6H)-ones 156 was achieved by heating the former with a mixture of triethyl orthoformate and acetic anhydride (1 1) [4],... 

Chloro-3,4-dihydronaphthalene-2-yl)methylene]amino -1 -phenyl-2-thioxo-1,6- dihydro[l,3]thiazolo[5,4-d]pyrimidin-7(2H)-one, which considered as a 7-thia analogue of the natural purine bases, adenine and guanine, was prepared in an excellent yield by condensing 189 with cyanoacetic acid hydrazide followed by Gewald reaction, by reaction of 190 with suhar and phenyl isothiocyanate in the presence of triethylamine as a basic catalyst to give 191(Scheme 84). Thiazolo[5,4-d]pyrimidinone derivative 192 was prepared by heating 191 with a mixture of triethylorthoformate and acetic anhydride (1 1) [117],... 

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