A Novel Synthesis of 5-Hydrazono-4a,7- dihydrodipyrazolo[3,4-b;4,3-e]pyridin-3(2H)-ones and their Cyclization to Fused Triazines Fawzy A. Attaby,*a Sanaa M. Eldinb and Mohamed A. A. El-Neairya aChemistry Department, Faculty of Science, Cario University, Giza, Egypt bNational Research Center, Dokki, Egypt Several 5-hydrazono-4a,7-dihydrodipyrazolo[3,4-b;4,3-e]pyridin-3(2H)-ones and triazines derived thereform were synthesized via the reaction of diazotized dipyrazolopyridines with active-methylene-containing reagents.In conjunction with our previous work1±5 and the reported biological activities of pyrazolopyridines8 as well as pyrazo- lotriazines9 we were interested to synthesize new compounds for our medicinal chemistry programme and to investigate novel chemical transformations. It has been found that 5-diazotized-4a,7-dihydrodi- pyrazolo[3,4-b;4,3-e]pyridin-3-(2H)ones (3a±c) couple with malononitrile (4a) to give the 4-amino-6,9-dihydro-10H- pyrazolo[40,30:5',6']pyrido[2',3':3,4]pyrazolo[5,1-c] [1,2,4]- triazin-10-one derivatives 6a±c, respectively.In contrast to the behaviour of 4a towards coupling with 3a±c, it was found that both ethyl cyanoacetate (4b) and o-cyanoaceto- phenone (4c) coupled with each of 3a±c to give the corre- sponding 5-hydrazono derivatives 5d±i, respectively, which cyclized to give the 4-amino-6,9-dihydro-10H-pyrazolo- [40,30:5',6']pyrido[2',3':3,4]pyrazolo[5,1-c][1,2,4]triazin-10-one derivatives 6d±i respectively (Scheme 1).The synthetic potential of 3a±c was further investigated through their reaction with other active-containing reagents. Thus 3a coupled with each of ethyl benzoylacetate (8a) and diethyl malonate (8b) to give the corresponding 5-hydrazono derivatives 9a±f respectively. Compounds 9a±f were cyclized J. Chem. Research (S), 1998, 632±633 J. Chem. Research (M), 1998, 2754±2768 Scheme 1 *To receive any correspondence. 632 J. CHEM. RESEARCH (S), 1998Scheme 2 in boiling ethanol that contained triethylamine to a€ord 10a�}f, respectively.The synthetic potential of 3a�}c was also further investigated through their reactions with cyanothio- acetamide (11a) and cyanoacetamide (11b) to a€ord the corresponding 5-hydrazono derivatives 12a�}f, respectively. Compounds 12a�}f readily underwent addition to the CN group to give the pyrazolo[40,30:5',6']pyrido[2',3':3,4]- pyrazolo[5,1-c][1,2,4]triazin-10-ones 15a�}f, respectively (Scheme 2). The synthons 3a�}c also reacted with each of acetylacetone (16a) and ethyl acetoacetate (16b) to a€ord the corresponding 5-hydrazono derivatives 17a�}f, respect- ively.Compounds 17a�}f were cyclized to a€ord 18a�}f, respectively, via loss of water. Techniques used: 1H NMR, FT-IR, UV and mass spectrometry Schemes: 2 References: 13 Table 1: Physical and analytical data of the compounds prepared Table 2: IR and 1H NMR spectral data of the newly synthesized compounds Received, 4th March 1998; Accepted, 25th June 1998 Paper E/8/01793J References cited in this synopsis 1 F. A. Attaby and S. M. Eldin, Phosphorus Sulfur, Silicon Relat. Elem., 1991, 55, 59. 2 F. A. Attaby, L. I. Ibrahim, S. M. Eldin and A. K. El-Louh, Phosphorus Sulfur, Silicon Relat. Elem., 1992, 73, 127. 3 F. A. Attaby and S. M. Eldin, Arch. Pharm. Res., 1990, 13, 274. 4 F. A. Attaby, Arch. Pharm. Res., 1990, 13, 342. 5 F. A. Attaby, S. M. Eldin and M. Abdel-razik, Phosphorus Sulfur, Silicon Relat. Elem., 1995, 106, 21. 8 M. Komura, R. Ishida and H. Uchida, Arzneim-Forsch., 1992, 42, 48. 9 D. R. Rao, S. P. Raychaudhuri and V. S. Verma, Int. J. Tropical Plant Dis., 1994, 12, 177. J. CHEM. RESE