Palladium-catalyzed regiodivergent arylamination/aryloxygenation of allenamide

Abstract

A palladium-catalyzed multi-component regiodivergent arylamination/aryloxygenation of allenamide is reported. The bases are critical to the chemoselectivity and regioselectivity: (1) Cy₂NMe as a base could lead to distal addition that generated a 2,1-arylamination product; (2) Ag₂CO₃ as a base could result in proximal addition for a 2,3-aryloxygenation product via a four-component transformation, including an unexpected CO₂ insertion from Ag₂CO₃. Notably, the corresponding alkenes formed in 2,3-arylamination could be presented with excellent Z configuration, which was modulated via the steric hindrance of a coordinated palladium intermediate. Two possible π-allyl-Pd complexes were proposed for the resulting regioselectivity: the neutral η³ π-allyl-Pd complex favored the γ substitution where there was less steric hindrance; cationic η¹ π-allyl-Pd complex generated via the coordination of Ag favored the reductive elimination at the allylic position adjacent to nitrogen.