Syntheses and structural studies of five-membered palladium complexes (3 which are formed by internal metallation of alkyl or aryl groups of co-ordinated ligands including amines (l), Schiff bases (2), azo-compounds (3) have received wide-spread attention; however, few studies have been carried out concerning to using these complexes for organic synthetic reactions (4). We wish to report facile carbon-carbon bond formation by the reaction of 1 with either alkyllithiums or Grignard reagents. This process provides a convenient method for selective syntheses of some ortho-alkyl substituted aromatic compounds which are difficult to be prepared (5) and gives important mechanistic insight into the carbon-carbon bond formation via palladium complexes. Reaction of di-~-chlorobis~o(N-phenylformimidoyl)phenyl~dipalladium (L), prepared from N-benzylideneaniline (5) in 95% yield (2), with methyllithium in ether gave N-(o-methylbenzylidene)aniline (3a) and kin 76% and 21% yields, respectively. Further reaction of Lwith tbutyllithium gave z (28%) and %(34%).
This reaction promises to provide a convenient method for synthesis of ortho-alkyl substituted aromatic compounds. Indeed, for synthesis of t-butylbenzaldehyde, six steps are required from t-butylbenzene, and its yield is extremely low (6).