Palladium(II) Acetate Catalyzed Reductive Heck Reaction of Enones; A Practical Approach

Abstract A surprisingly practical Pd(OAc) 2 or Pd(TFA) 2 ‐catalyzed reductive Heck reaction between aryl iodides and α,β‐unsaturated ketones is described using N,N ‐diisopropylethylamine (DIPEA, Hünigs base) as the reductant. In general, 1 mol % of Pd(OAc) 2 is sufficient to afford good yields using electron‐rich or halogen‐substituted aryl iodides. Electron‐deficient aryl iodides preferentially give homocoupling. Enones containing aryl or bulky substituents on the β‐carbon react smoothly, producing mainly reductive Heck product, whereas enones with alkyl substituents on the β‐carbon afford a mixture of reductive Heck and Heck product. Deuterium labeling experiments show that the reaction is a bona fide reductive Heck reaction and exclude a Heck reaction‐conjugate reduction cascade.