Intramolecular Pd-Mediated Processes of Amino-Tethered Aryl Halides and Ketones: Insight into the Ketone α-Arylation and Carbonyl-Addition Dichotomy. A New Class of Four-Membered Azapalladacycles

An exploration of the scope and limitations of Pd(0)-catalyzed intramolecular coupling reactions of amino-tethered aryl halides and ketones has been conducted. Two different and competitive reaction pathways starting from omega-(2-haloanilino) alkanones, enolate arylation and addition to the carbonyl group, have been observed, while omega-(2-halobenzylamino) alkanones exclusively underwent the enolate arylation process. The dichotomy between ketone alpha-arylation and carbonyl-addition in the reactions of omega-(2-haloanilino) alkanones has been rationalized by the intermediacy of unprecedented four-membered azapalladacycles, from which X-ray data and chemical behavior are reported.