New succinyl‐spaced pyrazoles: Regioselective synthesis of 1,4‐bis[5‐(trichloromethyl)‐1 H ‐pyrazol‐1‐yl]butane‐1,4‐diones

The facile and convenient access by a conventional procedure in ethanol as solvent to a new series of succinyl‐spaced pyrazoles including 1,4‐bis[5‐(trichloromethyl)‐5‐hydroxy‐4,5‐dihydro‐1 H ‐pyrazol‐1‐yl]butane‐1,4‐diones (64–82%) and the respective dehydrated derivatives as 1,4‐bis[5‐(trichloromethyl)‐1 H ‐pyrazol‐1‐yl]butane‐1,4‐diones in 57–82% yields, from the regioselective cyclocondensation reactions of 4‐substituted 4‐methoxy‐1,1,1‐trichloroalk‐3‐en‐2‐ones with succinic acid dihydrazide, where the 4‐substituents are Me, Ph, 4‐FC 6 H 4 , 4‐ClC 6 H 4 , 4‐NO 2 C 6 H 4 , 2‐furyl, and 2‐thienyl, is reported. J. Heterocyclic Chem., 2011.