Synthesis of some pyrazolo [3,4-d] pyrimidines and their fused triazole and tetrazole derivatives

Reaction of (2) with different reagents namely formic acid, acetic anhydrid e and trichloroacetonitrile yielded pyrazolo [3,4-d] pyrimidine derivatives (3,5 and 6) respectively. Pyrazolo [3,4-d] pyrimidine m-thiazine (7) and 2 ,4- (1H, 3H) dithione (8) derivatives were formed by the action of carbon d isulfide on (2) depending on the reaction medium. Interaction of (7) with h ydrazine hydrate yielded aminoimino derivative (9) which reacted with aceti c anhydride, triethylorthoacetate and/or appropriate aldehydes to give (11, 12, and 13a,b) respectively. Methylation of compound (8) gave (14), which r eacted with hydrazine hydrate to afford monohydrazino derivative (15). Reac tion of (15) with formic acid and nitrous acid afforded pyrazolo [4,3-e] tr iazolo [1,5-c] pyrimidine (16) and pyrazolo[4,3-e] tetrazolo-[1,5-c] pyrimi dine (17) derivatives, respectively. The structures of products (3-17) were established in light of their elemental analyses and spectral data.