1356175-75-1Relevant academic research and scientific papers
Regioselective synthesis of fused pyrazolo[1,5-a]pyrimidines by reaction of 5-amino-1H-pyrazoles and β-dicarbonyl compounds containing five-membered rings
Portilla, Jaime,Quiroga, Jairo,Nogueras, Manuel,Cobo, Justo
experimental part, p. 988 - 994 (2012/02/13)
Reactions of 3-substituted-5-amino-1H-pyrazoles with 2-acetylcyclopentanone or 2-ethoxycarbo-nylcyclopentanone lead to the regioselective formation of a new series of cyclopentapyrazolo[1,5-a]pyrimidines in good yields. When 2-acetylbutyrolactone was used, the reaction provided 6-(2-hydroxyethyl) pyrazolo[1,5-a]pyrimidinone and/or the intermediate (3Z)-3-{1-[(5-R-1H-pyrazol- 3-yl)amino]ethylidene}-4,5-dihydrofuranone. This indicates that the cyclization proceeds with butyrolactone ring opening as the last step. Several aspects of this regioselective reaction, including mechanistic and structural studies, are considered.
