Treatment of 2-cyano-N-(9, 10-dioxo-9, 10-dihydro-anthracen-2-yl)-acetamide (1) with phenyl isothiocyanate/dimethylsulphate afforded the corresponding ketene N, S-acetal 2 which upon treatment with hydrazine hydrate and 4-aminoantipyrine afforded the pyrazolo derivatives 3 and 4, respectively. 3-aminopyrazole derivative 3 was utilized as key intermediate for the synthesis of pyrazolo [3, 4-d] pyrimidine 5, pentaaza-as-indacene 6, ...
