Regioselective synthesis of multisubstituted pyrazoles via cyclocondensation of β-thioalkyl-α,β-unsaturated ketones with hydrazines

Multisubstituted pyrazoles were efficiently synthesized by cyclocondensation of β-thioalkyl-α,β-unsaturated ketones with hydrazines under relatively mild conditions. A one-pot synthetic protocol through tandem Liebeskind-Srogl cross-coupling/cyclocondensation using α-oxo ketene dithioacetals as the starting materials was also realized for the same purpose.