SYNTHESIS OF DIPOLAR ETHYLENEIMIDAZOLIUM BENZIMIDAZOLATE INNER SALTS AND THEIR TRANSFORMATION TO 2-VINYLBENZIMIDAZOLES THROUGH A TYPE OF BETA-ELIMINATION REACTION
E. Alcalde et al., SYNTHESIS OF DIPOLAR ETHYLENEIMIDAZOLIUM BENZIMIDAZOLATE INNER SALTS AND THEIR TRANSFORMATION TO 2-VINYLBENZIMIDAZOLES THROUGH A TYPE OF BETA-ELIMINATION REACTION, Heterocycles, 43(3), 1996, pp. 567-580
The synthesis and spectroscopic properties of the fairly stable title
inner salts (5) are reported. For several of the betaines (5), both th
e highly dipolar character due to the terminal rings and the nature of
the spacer promoted a type of beta-elimination reaction. Thus, format
ion of 2-vinylbenzimidazoles (7) from the corresponding betaines (5) p
roceeds in high yield under neutral and mild conditions. Following sim
ilar treatment, the 1-(2-benzimidazol-2-ylethyl)imidazolium salt (8b)
undergo nucleophilic substitution reactions.