5‐Amino‐3‐phenylpyrazole (I) and 5‐amino‐4‐bromo‐3‐phenylpyrazole (II) reacted with ethyl acetoacetate and acetylacetone to give various pyrazolo[1,5‐a]pyrimidines IV‐VI and with benzoins to give different fused pyrazoles, namely, imidazo[1,2‐b]pyrazoles IX, pyrrolo[2,3‐c]pyrazoles X and pyrazolo[4,3‐b][1,4]oxazines XII. Diazotized II was coupled with active methylene‐containing nitriles to afford pyrazolo[5,1‐c]‐as‐triazines XIV.
Whereas acetoacetanilide (II) reacted with α‐cyano‐ and α‐benzoylcinnamonitrile derivatives Ia‐e to give hexa‐substituted pyridines III and V, it reacted with α‐carboxamido‐ and α‐thiocarboxamidocinnammonitrile derivatives If‐h to afford penta‐substituted pyridines VI. One mole of acetonedicarboxylic acid dianilide (VII) reacted with two moles of each of α‐cyano‐ and α‐thiocarboxamidocinnamonitriles Ia,b,f,g to yield the dipyridyl ketones VIII and IX, respectively. On the other hand, α‐benzoyl‐ and α‐ethoxycarbonylcinnamonitriles Ic,d,i,j reacted with VII in equimolecular ratio to give the pyran derivaties X and XI, respectively. Several schemes were proposed to illustrate reactions steps. The structures of the synthesized compounds were proved by chemical and spectral methods.
The reactivity of heterocyclic α,β-unsaturated ketones towards the title compounds has been studied. A pyrimidine, pyrazoline, isoxazoline and a fused pyrrolidine rings have been built up. Mannich reaction was tried with the pyrazoline derivative (4 d). Bromination of the 2-cinnamoyl compounds (1 a-c), and cyclization of the products were also undertaken.
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