Replacement of Imine Fragment in the Ring of 2,6-Disubstituted 1,4,3,5-Octathiadiazine-4,4-dioxides in Reaction with Cyano-containing Compounds

Reactions of 2,6-disubstituted 1,4,3,5-octathiadiazine-4,4-dioxides with cyano-containing compounds (nitriles, thiocyanates, N,N-disubstituted cyanamides) proceeding with replacement of imine fragment in dioxide by corresponding fragment of cyanide were investigated. The limits of the reaction were revealed determined by electronic effects of substituents R1 and R2 in dioxide and R3 in cyanide. Transimination occurred in dioxides with strong electron-withdrawing substituents R1 (CCl3, CBr3, C6F5) and weak acceptor or donor substituents R2(4-NO2C6H4, 4-ClC6H4, CH3) under the action of compounds R3C≡N with cyano groups of relatively high nucleophilicity (R3 = 4-ClC6H4, C6H5, (CH3)2CHS, piperidino, morpholino, diethylamino), on the one hand, and with strong electron-withdrawing substituents R3 (CCl3) on the other hand.