1,3-Dipolar cycloaddition of nitrile imines with a,b-unsaturated five- and six-membered lactones, thiolactones and lactams gave ring-fused pyrazoles. Regioisomeric mixtures have been obtained with the 5- substituted pyrazole as the major cycloadduct. Only with the five-membered lactone the major product was the 4-acyl derivative. Computational studies, the use of the topological analysis of the Fukui functions and the potential energy surfaces (PES) theory allowed a theoretical description of the local reactivity in agreement with the observed high regiochemistry and with the role of the heteroatom adjacent to the carbonyl group
J. Z. Chandanshive, P. Blas Gonzalez, W. Tiznado, B. Bonini, J. Caballero, C. Femoni, et al. (2012). 1,3-Dipolar cycloaddition of nitrile imines with a,b-unsaturated lactones, thiolactones and lactams: synthesis of ring-fused pyrazoles. TETRAHEDRON, 68, 3319-3328 [10.1016/j.tet.2012.02.068].
1,3-Dipolar cycloaddition of nitrile imines with a,b-unsaturated lactones, thiolactones and lactams: synthesis of ring-fused pyrazoles
FEMONI, CRISTINA;COMES FRANCHINI, MAURO
2012
Abstract
1,3-Dipolar cycloaddition of nitrile imines with a,b-unsaturated five- and six-membered lactones, thiolactones and lactams gave ring-fused pyrazoles. Regioisomeric mixtures have been obtained with the 5- substituted pyrazole as the major cycloadduct. Only with the five-membered lactone the major product was the 4-acyl derivative. Computational studies, the use of the topological analysis of the Fukui functions and the potential energy surfaces (PES) theory allowed a theoretical description of the local reactivity in agreement with the observed high regiochemistry and with the role of the heteroatom adjacent to the carbonyl groupI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
