PALLADATION AND SUBSEQUENT FUNCTIONALIZATION AT THE 2ND PERI POSITION OF 1-SUBSTITUTED NAPHTHYL GROUPS

The cyclopalladation of ligands having a naphthyl group substituted at the 1-position by either amino or imino units has been studied. Palladation of the naphthyl unit occurs as expected at the second peri position of the N,N-dialkylamino substituted derivatives. However, the imines were not palladated at the 8-position of the naphthyl unit. The last ligands were synthesized by condensation of either acetone or acetophone on Pd(1-aminonaphthalene)2Cl2. In the case of the acetone derivative, this afforded a Pd complex having two imines N-coordinated to the metal; the compound obtained with acetophenone did lead to a cyclopalladation product, but the metallation occurred at the ortho position of the phenyl group of the acetophenone unit rather than on the 8-position of the 1-iminonaphthalene. The cyclopalladated compounds obtained with the 1-N,N-dialkylaminonaphthalenyl ligands afforded reasonable yields of N-alkylquinolines through reaction with internal alkynes such as tolane, dimethylacetylenedicarboxylate, and ethyl-3-phenylpropynoate. Thus, starting with the cyclopalladated 9-dimethylaminophenanthrene, good yields of aporphine precursors can be obtained.