Ligand-free cationic Pd(II) catalyst with NaNO3 as an additive is a highly active catalytic system for conjugate additions to sterically hindered ?-substituted cyclohexenones. More challenging ??- and ß?-substrates also react well to produce products with quaternary centers in good dr. The conjugate additions occur in a diastereoselective fashion under mild, practical and air-stable conditions, using readily available commercial reagents.
Jordan-Hore, J., Lee, A-L., & Sanderson, J. N. (2012). Mild and Ligand Free Pd(II)-Catalyzed Conjugate Additions to Hindered γ-Substituted Cyclohexenones. Organic Letters, 14(10), 2508-2511. https://doi.org/10.1021/ol300794a