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Synfacts 2011(3): 0263-0263  
DOI: 10.1055/s-0030-1259562
Synthesis of Heterocycles
© Georg Thieme Verlag Stuttgart ˙ New York

CuI/I2-Mediated Synthesis of Iodoisoquinoline-Fused Benzimidazoles

Contributor(s): Victor Snieckus, Toni Rantanen
H.-C. Ouyang, R.-Y. Tang, P. Zhong*, X.-G. Zhang, J.-H. Li*
Wenzhou University and Hunan Normal University, Changsha, P. R. of China
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Publication History

Publication Date:
16 February 2011 (online)

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Significance

The iodine-mediated, CuI-catalyzed synthesis of iodoisoquinoline-fused benz­imidazoles from 2-ethynylbenzaldehydes and o-benzenediamines is reported. NIS, NBS and NCS were tested as well; NIS afforded lower yields compared to I2, NBS afforded the product (single case) in 48% yield, and NCS failed to ­perform as a reagent. The control experiment showed that two equivalents of CuI are sufficient for effecting the ­cyclization step (no incorporation of iodine). The substrate scope was quite well studied, yields range from poor to good, and one of the products (R¹ = H, R² = Ph, R³ = H) was used in Sonogashira, Heck, and Suzuki coupling reactions, demonstrating further versatility.