Oxoiminium Ions for N-Demethylation: 1-Oxo-2,2,6,6,-tetramethylpiperidinium Chloride

Article abstract of DOI:10.1021/jo00241a028

In an attempt to assess the synthetic utylity of oxoiminium ions as oxidizing agents and to delineate their reaction mechanisms, we reacted 1-oxo-2,2,6,6-tetramethylpiperidinium chloride (1) with several N,N-dialkylanilines.With N,N-dimethylaniline the only basic product was N-nethylaniline while N- methylformanilide was the only neutral product.The relative amounts of base and neutral product proved to be sensitive to the amount of water present in the reaction medium.With N-alkyl-N-methylanilines, the basic products were N-alkylanilines from exlusive loss of the N-methyl group.The neutral products were the N-alkylformanilides.The alkyl groups studied were ethyl, n-butyl, isopropyl, and benzyl.With N-tert-butyl-N-methylaniline, there was no observed reaction, and N,N-diethylaniline was found to be significantly less reactive than N,N-dimethylaniline.This study has shown that 1 is selective in N-demethylation of anilines in the presence of other alkyl groups either on the same nitrogen or on separate nitrogens.These results have been interpreted in terms of important steric interactions resulting from formation of an adduct en route to an intermediate iminium ion.