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Synfacts 2008(10): 1116-1116  
DOI: 10.1055/s-2008-1078203
Polymer-Supported Synthesis
© Georg Thieme Verlag Stuttgart ˙ New York

Microwave-Assisted Synthesis of Benzimidazoles from Resin-Bound Esters

Contributor(s): Yasuhiro Uozumi, Toshimasa Suzuka
H.-J. Lim*, D. Myung, I. Y. C. Lee, M. H. Jung
Korea Research Institute of Chemical Technolgy, Daejeon, Korea
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Publication History

Publication Date:
22 September 2008 (online)

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Significance

Solid-phase synthesis of benzimidazoles via microwave-assisted condensation of resin-bound esters with 1,2-phenylenediamine is described. Thus, the resin-bound esters 2a-d were prepared from the corresponding acid chloride (RCOCl) with Wang resin. Microwave-assisted condensation of 2a with 1,2-phenylenediamine was carried out in the presence of polyphosphoric acid (PPA) in NMP at 150 ˚C for 10 min and then at 230 ˚C for 30 min to give 2-phenylbenzimidazole 3aa in 94% yield. The condensation reactions of esters 2a-d and diamine 4 took place with the aid of microwave irradiation to give the corresponding imidazoles 3 in 47-96% yield.