Sherif Mahmoud Fahmy

Pyrimidine Derivatives and Related Compounds, IX / Preparation of 5-Aminopyrazolo[1,5-a]pyrimidines and of Oxazino[4,5 : 5,6]pyrazolo[1,5-a]pyrimidines, a New Ring System

Whereas the 5-aminopyrazole derivatives (1 a, b) react with ethyl β-amino-β-trichloro-methylmethylenecyanoacetate (2) in basic media to yield the corresponding 5-aminopyrazolo[1,5-a]pyrimidine derivatives (3a, b), the reaction of la, b with 2 in refluxing acetic acid has afforded oxazino[4,5:5,6]pyrazolo[1,5-a]pyrimidine derivatives. 5-Amino-3-phenyl-4-phenylazopyrazole (12) reacted with 2 in refluxing pyridine to yield the 5-amino-2-phenyl-3-phenylazopyrazolo[1,5-a]pyrimidine derivative (18). On the other hand, the reaction of 12 and 2 in refluxing acetic acid has afforded a mixture of the oxazino[4,5:5′,6′]pyrazolo[1,5-a]pyrimidine derivatives (14) and the pyrazolo[3,4-d]-astriazine derivatives (15). The mechanism of the formation of reaction products is discussed.

Pyrimidine Derivatives and Related Compounds, VII Synthesis of Some New Pyrazolo [1,5-a] -S-triazines, Pyrazolo [3,4-c] -as-triazines, Pyrazolo [1,5-a] pyrimidines and Pyrazolo [3,4-b] pyrones

3-Amino-4-phenylhydrazono-2-pyrazolin-5-one (1) reacts with isothiocyanate to yield the corresponding pyrazolylthiourea derivatives (2 a-c). Whereas 2 a reacted with hydrazines to yield the pyrazolylamino-1,2,4-triazoles (3 a, b), it cyclised into the pyrazolo-[3,4-e]-as-triazine derivative (4) upon treatment with concentrated sulphuric acid. On the other hand, the pyrazolo[1,5-c]-S-triazine derivative (5) was formed from reaction of 2a with ethanolic sodium ethoxide. 3-Amino-2-pyrazolin-5-one (8) reacted with ethyl acrylate to yield a mixture of the 4-dialkylated derivative (9) and the pyrazolo[3,4-b]pyrone (11). Compound 11 could be converted into the corresponding pyrazolo[3,4-b]pyrones (12) and (13) by the action of acetic acid hydrochloric acid mixture and of concentrated sulphuric acid, respectively.

Reactions with 5-Arylmethylene-2-phenylhydrazono-4-thiazolidinones A Novel Synthesis of Thiazolo[2,3-c]triazine Derivatives

The 5-arylmethylene derivatives of 2-phenylhydrazono-4-thiazolidinone (1) reacted with phenacyl bromide and with ethyl bromoacetate to yield the thiazolo[2,3-c]triazine derivatives (3) and (4). The reaction of 1 with carbon disulphide in alkaline solution afforded the bis(N1- 2-phenylhydrazono-4-thiazolidinone)thiocarbonyl derivatives (6). Cyanoethylation of 1 afforded the N1-β-cyanoethylphenylhydrazono derivatives (7).