Direct Access to 9-Chloro-1H-benzo[b]furo[3,4-e]azepin-1-ones via Palladium(II)-Catalyzed Intramolecular syn-Oxypalladation/Olefin Insertion/sp2-C–H Bond Activation Cascade

An efficient Pd(II)-catalyzed cascade approach was established for the synthesis of 9-chloro-1 H -benzo[ b ]furo[3,4- e ]azepin-1-ones starting from N -propargyl arylamines having a pendant α,β-unsaturated ester scaffold. The mechanism of this sequential process involved intramolecular syn -oxypalladation followed by olefin insertion and ortho sp 2 -C–Cl bond formation reactions. This high atom- and step-economical cascade sequence generated two heterocycle rings and three new bonds in a single synthetic operation.