Silver(I)-catalyzed reaction between pyrazole and propargyl acetates: stereoselective synthesis of the scorpionate ligands (E)-allyl-gem-dipyrazoles (ADPs).

The reaction between readily accessible pyrazole and propargyl acetates in the presence of Ag(I) catalyst yielded a new class of (E)-allyl-gem-dipyrazole scorpionate ligands: 1-aryl-2-N-pyrazolyl allyl acetates and 1,3-dipyrazolyl-3-arylpropene. The reaction showed broad substrate scope, and various functional and protecting groups were tolerated under the reaction conditions. The palladium(II) scorpionate complex could thus be easily prepared and successfully employed in Suzuki-Miyaura cross-couplings in water.