A facile organocatalyzed Michael addition of pyrazolines to α,β-unsaturated carbonyl compounds

A new highly efficient cascade reaction of pyrazolines with α,β-unsaturated carbonyl compounds catalyzed by DBU was reported. The process underwent the first deprotection/Michael addition reaction to give 4-substituted pyrazoline derivatives, which were further converted into 4,4-di-substituted pyrazolone derivatives through the second deprotection/Michael reaction. The mechanism for this reaction was also studied.