Isoquinolinium Salt Syntheses from Cyclopalladated Benzaldimines and Alkynes

Article abstract of DOI:10.1021/jo00249a018

Cyclopalladated, N-substituted benzaldimine tetrafluoroborates react with disubstituted alkynes in poor to good yields to form isoquinolinium tetrafluoroborates.The reaction is particularly useful for preparing trisubstituted products.Electron-donating substituens may be presented at the 5, 6, 7, and 8 positions, as well.Methyl (p-benzoxyphenyl)propiolate adds to cyclopalladated N-methyl-3-benzoxy-4-methoxybenzaldimine tetrafluoroborate to form the 3-arylisoquinolinium salt. 3-Hexyne reacts with cyclopalladated N-phenylbenzaldymine chloro dimer at 150 deg C to form the isoquinolinium chloride but at less than half (29percent) the yield that is obtained from the corresponding tetrafluoroborate.