Ambident heterocyclic reactivity: Intramolecular alkylations of 2,4-disubstituted benzimidazoles
作者:M. Rezaul Haque、Malcolm Rasmussen
DOI:10.1016/s0040-4020(97)00394-3
日期:1997.5
2-(3-chloropropyl)- and 2-(4-chlorobutyl)-4-substituted benzimidazoles bearing 4-nitro-, 4-amino-, and 4-methyl groups show enhanced regioselectivity compared to the corresponding intermolecular alkylations with 1-chlorobutane. The observed N1:N3 cyclization ratios vary from 94:6 to 10:90, with the largest preference for reaction at the ‘congested’ N3-site occurring in the 5-membered ring formation