The Open Organic Chemistry Journal
2008, 2 : 92-99Published online 2008 November 12. DOI: 10.2174/1874095200801020092
Publisher ID: TOOCJ-2-92
Solvent-Free Synthesis of Fused Pyrazolo[1,5-a]pyrimidines by Reaction of 5-Amino-1H-pyrazoles and β -Triketones
Grupo de Investigación de
Compuestos Heterocíclicos, Departamento de Química, Universidad del
Valle, A.A. 25360, Cali, Colombia and Grupo de Investigación en
Compuestos Bio-orgánicos, Departamento de Química, Universidad de los
Andes, Carrera 1 N° 18A 10, Bogotá, Colombia.
ABSTRACT
The solvent-free reaction between 5-amino-1H-pyrazoles and β-triketones (2-acetyldimedone and 2- acetylindandione) leads to the formation of new fused pyrazolo[1,5-a]pyrimidines in good yields. A possible mechanistic route is postulated on the basis of the isolation of the cyclization intermediate. The structures and regiospecificity of the reaction were determined on the basis of nmr measurements and X-ray diffraction.