N-alkyl-4-(N′,N′-dialkylamino)pyridinium salts: thermally stable phase transfer catalysts for nucleophilic aromatic displacement

N-Alkyl salts of 4-dialkylaminopyridines are effective phase transfer catalysts which are up to 100 times more stable than tetrabutylammonium bromide to conditions encountered in nucleophilic aromatic substitution reactions. These salts are thermally stable to over 300°C, and promote reactions in non-polar solvents (or in the absence of solvent) at temperatures as high as 200°C.