Rh-Catalyzed Sequential Hydroarylation/Hydrovinylation-Heterocyclization of β-(2-Aminophenyl)-α,β-ynones with Organoboron Derivatives: A New Approach to Functionalized Quinolines
4-Aryl and 4-vinyl quinolines were prepared via a sequential procedure involving regioselective Rh(acac)(C2H2)/dppf-catalyzed hydroarylation/hydrovinylation of β-(2-aminophenyl)-α,β-ynones with arylboronic acids or potassium aryl and vinyl trifluoroborates, followed by nucleophilic attack of the amino group onto the carbonyl.
Difficult-to-access 4-bromo quinolines are constructed directly from easily prepared ortho-propynol phenylazides using TMSBr as acid-promoter. The cascade transformation performs smoothly to generate desired products in moderate to excellent yields with good functional groups compatibility. Notably, TMSBr not only acted as an acid-promoter to initiate the reaction, and also as a nucleophile. In addition