Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5221021 | Tetrahedron | 2012 | 7 Pages |
Abstract
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.
Download full-size image
Related Topics
Physical Sciences and Engineering
Chemistry
Organic Chemistry
Authors
Jaime Portilla, Jairo Quiroga, Manuel Nogueras, Justo Cobo,