A solid phase traceless synthesis of 2-arylaminobenzimidazoles

A solid phase traceless synthesis of 2-arylaminobenzimidazoles in three combinatorial steps is reported that is based on acid lability of N-benzylanilines. MBHA resin was reacted with o-nitrobenzenes, the nitro group was reduced by tin(II) chloride, the resin-bound o-phenylene diamine was treated with isothiocyanates, and the resulting thiourea cyclized by carbodiimide. 2-Arylaminobenzimidazoles were further derivatized with alkyl halides. Target compounds were cleaved from the solid support by TFA or gaseous HF.