Heterocyclic Betaines. XXIII. Access to Novel Dipolar Ethyleneimidazolium(pyridinium) 4-Nitrobenzimidazolate Inner Salts. Synthesis, Characterization and Reactivity Concerning a Type of .BETA.-Elimination Reaction.
The first synthesis of the hitherto unknown ethyleneimidazolium benzimidazolate inner salts is described. Their dipolar structure is well reflected on the basis of the 1H and 13C NMR parameters. Under neutral and mild conditions the title compounds underwent a type of β-elimination, affording their corresponding 2-vinyl-1H-benzimidazoles in high yields.
Transformation of several 1-(2-benzimidazol-2-ylethyl)pyridinium salts, obtained by two different procedures, into their corresponding 2-vinylbenzimidazoles either using an anion-exchange resin (OH- form) or in the solid state is described. This approach now allows a facile entry into the almost unknown 2-vinylbenzimidazole monomers.
Heterocyclic Betaines. XXIII. Access to Novel Dipolar Ethyleneimidazolium(pyridinium) 4-Nitrobenzimidazolate Inner Salts. Synthesis, Characterization and Reactivity Concerning a Type of .BETA.-Elimination Reaction.
The first synthesis of some imidazolium(pyridinium) 4-nitrobenzimidazolate betaines with an ethylene interannular spacer has been performed. Their chemical behavior concerning a type of β-elimination reaction has also been studied and contrasted to that of their pyridinium counterparts.