Pyridine‐Hydrazone Ligands in Asymmetric Palladium‐Catalyzed 1,4‐ and 1,6‐Additions of Arylboronic Acids to Cyclic (Di)enones

Catalysts generated by combinations of Pd(TFA)2 and enantiomerically pure pyridine‐hydrazone ligands have been applied to the 1,4‐addition of arylboronic acids to β‐substituted cyclic enones, building all‐carbon quaternary stereocenters in high yields and enantioselectivities (up to 93% ee). The developed methodology allows the efficient introduction of ortho‐substituted aryl groups in β‐position of cyclopentanone cores, giving scaffolds present in a broad range of biologically active natural products. These Pd(II)‐complexes served also as catalysts in the 1,6‐addition of arylboronic acids to cyclic dienones, affording complete regioselectivities, moderate yields and good enantioselectivities (up to 80% ee).