peri-naphthylenediamines 31. Study of interconversions of 2,3-dihydroperimidines and 1,8-bis(dialkylamino) naphthalenes. Convenient synthesis of 1,2,2,3-tetramethyl-2,3-dihydroperimidine and a monoisopropyl analog of the "proton sponge"

Efficient procedures were developed for the two-step synthesis of 1,2,2,3-t etramethyl-2,3-dihydroperimidines and for the one-step synthesis of 1,3-dim ethyl-2,3-dihydroperimidines starting from 1,8-diaminonaphthalenes. New pos sibilities of the use of 2,3-dihydroperimidinium salts in the synthesis of 1,8-bis(dialkylamino) naphthalenes ("proton sponges") containing the IV-iso propyl group along with the A-methyl groups were demonstrated. The 1,1,2,2, 3-pentamethyl-2,3-dihydroperimidinium cation exists in the acyclic iminium form responsible for its high reactivity.