الفهرس 
ctivated Nitriles in Heterocyclic Synthesis:Only 14 pages are availabe for public view
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Abstract
-Amino-3-phenylpyrazole (1) reacts with 3a to yield a product of molecular formula C19H140 N4.Four theoretically possible isomeric structures were consid ered (cf. structures 4-7, Chart 1). structures 4,5 were readily eliminated based on IH NMR spectrum which revealed pyrazole CH at ~ 6.2 ppm. Structure § could be also elimin ated based on IR spectrum which revealed CO absorption at 1660 em-I. If this compound is £,CO absorption at higher frequence (ca. 1700 em-I) would have been revealed.
Similar to the behaviour of 1 with 3a, compound 1 reacted withbenzylidinemalononitrile (3b) to yield the pyrazolo [1, 5-a) pyrimidine derivative ,2. Compound}. reacted also with c(-cyanochalcone (]£) to yield the pyrazolo(1,5-a] pyrimidine derivative 10. The formation of 10 is assumed to proceed via inicial formation of the Michael adduct 11 elimination of water to yield the final isolable 10
Similar to the behavior of 1 , compound 2 reacted with 3b to yield cyclocondensation product of molecular formula C13HI10 N5 • Six isomeric structures were considered (cf. J~ 17). Although structures 12-15 seemed for the first glance unlikely based on analogy to the behaviour of 1 toward 3a the activativing effect of the carbonyl function in 2 to the methylene C-4 made such arguments not convensing and an independent structure proof seemed nessary. Structures 12-14
could be readily eliminated based on the isolation of the amide 18 on prolonged refluxed of the reaction product or of 1 and 3b in ethanolic piperidine mixture. This compound can only result from hydrolysis of the pyrano[2,3-c]pyrazole derivative 17,thus, establishing this structure for the reaction.