A Modified, Economical and Efficient Synthesis of Variably Substituted Pyrazolo[4,3‐d]pyrimidin‐7‐ones.

Abstract

Fused pyrimidine derivatives R 0515 A Modified, Economical and Efficient Synthesis of Variably Substituted Pyrazolo[4,3-d]pyrimidin-7-ones. -An efficient microwave-assisted synthesis of the title compounds (VI) (13 examples) is developed. -(KHAN*, K. M.; MAHARVI, G. M.; CHOUDHARY, M. I.; ATTA-UR-RAHMAN; PERVEEN, S.; J. Heterocycl. Chem. 42 (2005) 6, 1085-1093; H. E. J. Res. Inst. Chem., Univ. Karachi, Karachi 75270, Pak.; Eng.) -R. Staver

Electrooxidation Is a Promising Approach to Functionalization of Pyrazole-Type Compounds

“…The reaction of alkyl-substituted pyrazoles and their carboxylic acids with Br 2 (at 20–25 °C) proceeded in yields of 75–96% in non-aqueous media (CH 2 Cl 2 , CHCl 3 or CCl 4 ) [ 45 , 56 , 57 , 58 ], or 50–75% in water [ 59 , 60 ]. The NaOH additives (which binds with HBr formed) allows bromination of low-reactive pyrazole-3-carboxylic acid in the yield of 90% [ 61 ].…”

Synthesis of pyrazolo[4,3-e][1,2,4]triazine sulfonamides, novel Sildenafil analogs with tyrosinase inhibitory activity

“…13 Moreover, this system, for example, pyrazolo [4,3-e] [1,2,4]triazine is structurally related to pyrazolo [4,3-d]pyrimidin-7-one present in the structure of Sildenafil and its methyl ether analogs which were found to show tyrosinase inhibitory effect, apart from its well-known orally effective properties for the treatment of male erectile dysfunction. 14,15 It should be noted that so far no analogs of Sildenafil containing the skeleton of 1H-pyrazolo [4,3-e] [1,2,4]triazine ring system have been described in the literature. With regard to the above discussed facts, we envisage a high potential of the pyrazolo [4,3-e] [1,2,4]triazine system regarding the discovery of new biological activities.…”