Conversion of novel palladacycles into oxopyrrolo[3,4-b]quinolines

The quinolinylcyclopalladated complexes 3a–b were synthesised in good yields (81% and 77%) by the insertion reaction of the prepared dinuclear palladium complexes [Pd(C,N-2-C9H4N-CHO-3-R-6)Cl(PPh3)]2 [(R = H (2a), R = OMe (2b)] with isonitrile XyNC (Xy = 2,6-Me2C6H3). The cyclopalladated complexes 3a–b were also obtained in low yields (39% and 33.5%) via a one pot oxidative addition reaction of quinoline chloride 1a–b with isonitrile XyNC:Pd(dba)2 (4:1). The reactions of 3a–b with Tl(TfO) (TfO = triflate, CF3SO3) in the presence of H2O or EtOH causes depalladation reactions of the complexes to provide the corresponding organic compounds 4a–b, 5a–b and 6a–b in yields (41%, 27% and 18–19%). The products were characterized by satisfactory elemental analyses and spectral studies (IR, 1H, 13C and 31P NMR). The crystal structures of 2a, 3a and 3b were determined by X-ray diffraction studies.

Some palladacycles have been synthesized from three simple and readily available building blocks via a one-pot oxidative addition reaction of quinoline chlorides to Pd(dba)2 and isocyanide XyNC or via the direct insertion reaction of XyNC into the prepared novel dinuclear palladium complexes. Depalladation reaction of the palladacycles could convert them into organic molecules. The sequence of reactions led eventually to compounds that could potentially possess pharmacological properties. The solid state structures of selected complexes 2a, 3a and 3b show interesting features.Figure optionsDownload as PowerPoint slide