Sterically Hindered Ketiminium Salts: a New Generation of Phase-Transfer Catalysts

Sterically hindered hydrazone 2 undergoes an unpredicted N–N bond scission via a methiodination sequence leading to iminium salt 5. This latter compound was found to be remarkably stable under basic and acidic conditions and it proved to be able to promote C-alkylation of the glycine derived imine 7 under classical catalytic liquid–liquid phase-transfer conditions. Both the reaction cleavage and the catalytic potential are discussed.