Polymer-Assisted Parallel Solution Phase Synthesis of Substituted Benzimidazoles

A small library of benzimidazoles was prepared using polymer-bound reagents and scavengers. Polymer-assisted reaction of diphenyl diamines with carboxylic acids yielded o-amido-diphenylamines in the presence of Polystyrene-Carbodiimide (PS-Carbodiimide) using 1-hydroxy-7-azabenzotriazole (HOAt) as additive. Excess HOAt was scavenged post-reaction using Polystyrene-Trisamine (PS-Trisamine) resin. Treatment of o-amido-diphenyl­amines with AcOH facilitated acid-catalyzed cyclodehydration to afford benzimidazoles in good yields and excellent purities.