1,3-Dipolar cycloaddition of nitrile imines with alpha,beta-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 ...
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http://dspace.utalca.cl/handle/1950/9095
