Palladation of 8-methylquinoline and related 2-substituted derivatives: evidence for in-plane metallation of methyl groups

Abstract

8-Methylquinoline reacts with palladium acetate to give palladation at the 8-methyl group and similar metallations occur for 2-substituted derivatives where one would expect the substituent R to allow chelate ring formation (R = CH:NMe, CO₂H, or CH₂OH) but not where R = Me, Br, or CHO; evidence is presented for metallation occurring when the ligand plane and the co-ordination plane are coincident.