Conversion of iminoacyl quinolinylpalladium (II) complexes into novel oxo‐pyrrolo[3,4‐b] quinolines via depalladation reactions

Abstract

AbstractOxidative addition reactions of quinolines 1a, b with Pd(dba)2 in the presence of PPh3 (1:2) in acetone gave dinuclear palladium complexes [Pd(C,N‐2‐C9 H4N‐CHO‐3‐R‐6)Cl(PPh3)]2 [(R = H (2a), R = OMe (2b), which were reacted with isocyanide XyNC (Xy = 2,6‐Me2C6H3) to give novel iminoacyl quinolinylpalladium complexes 3a, b in good yields (81 and 77%). Cyclopalladated complexes3a, b were also obtained in low yields (39 and 33.5%) via one‐pot reaction of 1a, b with isonitrile XyNC:Pd(dba)2 (4:1). The reaction of 3a,b with Tl(TfO) (TfO = triflate, CF3SO3) in the presence of H2O or EtOH causes depalladation reactions of complexes to provide the corresponding organic compounds 4a, b, 5a, b and 6a, b in yields of 41, 27 and 18 − 19%, respectively. The products were characterized by satisfactory elemental analyses and spectral studies (IR, 1H, 13C and 31P NMR). The crystal structures 2a, 3a and3b were determined by X‐ray diffraction studies. Copyright © 2008 John Wiley & Sons, Ltd.