Pyridine–Hydrazones as N,N′‑Ligands in Asymmetric Catalysis: Pd(II)-Catalyzed Addition of Boronic Acids to Cyclic Sulfonylketimines

The design, synthesis, and coordination features of a novel class of chiral pyridine–hydrazone ligands are described. As a first application, L/Pd­(TFA)2 complexes served as catalysts in the 1,2-addition of arylboronic acids to saccharin-derived cyclic ketimines, affording products in high yields and enantioselectivities. The method was also applied to more challenging 3,4-disubstituted 1,2,5-thiadiazole 1,1-dioxides, affording again high yields and enantioselectivities along with high regioselectivities for unsymmetrically substituted derivatives.