
%0 Journal Article
%A Howell, JR 
%A Rasmussen, M 
%T Heterocyclic Ambident Nucleophiles. V. Alkylation of Benzimidazoles
%J Australian Journal of Chemistry
%D 1993/08/01
%V 46
%N 8
%P 1177-1191
%K 
%R https://doi.org/10.1071/CH9931177
%U https://www.publish.csiro.au/paper/CH9931177 
%X Alkylation of 5-substituted benzimidazole anions with a variety of primary alkyl halides in both protic and aprotic solvents showed only small regioselectivity , with a slight preference for reaction at N1 for 5-nitro and N3 for 5-methoxy systems. With 4-substituted benzimidazole anions, alkylation gave more divergent results with the N1 to N3 regioselectivity varying between 100:0 and 29:71. These alkylation patterns are interpreted as deriving from an interplay of electrostatic, thermodynamic, steric and associative control factors within the variable SN2 transition state structures involved. In the 4-substituted series, proximity effects, both electrostatic field and steric non-bonded, are clearly dominant. 
