Regiodivergent Synthesis of 1,3‐ and 1,4‐Enynes through Kinetically Favored Hydropalladation and Ligand‐Enforced Carbopalladation

Pd‐catalyzed hydroalkynylations were developed that involve ligand‐enabled regiodivergent addition of an alkyne to an allenamide, giving branched and linear products stereoselectively and facilitated by the neighboring amide group. Regioselectivity was achieved with the use of (o‐OMePh)3P and BrettPhos, which allowed the functionalization of various alkynes, including steroids, carbohydrates, alkaloids, chiral ligands, and vitamins. Based on the experimental results, it was proposed that hydro‐ and carbopalladation processes operated during the formations of the branched and linear products, respectively. Pd‐catalyzed hydroalkynylations involving ligand‐enabled regiodivergent addition of an alkyne to an allenamide stereoselectively gave branched and linear products facilitated by the neighboring amide group. Regioselectivity was achieved with the use of (o‐OMePh)3P and BrettPhos. Hydro‐ and carbopalladation processes were shown to operate during the formation of the branched and linear products, respectively.