Regioselective synthesis of 1,3,4,5-tetrasubstituted pyrazoles from Baylis–Hillman adducts

Tetrasubstituted pyrazole derivatives 3a–j were synthesized regioselectively in good yields from the reaction of Baylis–Hillman adducts 1a–f and hydrazine hydrochlorides 2a–d in 1,2-dichloroethane.