Journal Article Selective and Gram-Scale Synthesis of [6]Cycloparaphenylene

Kayahara, Eiichi  ,  Patel, Vijay  ,  Xia, Jianlong  ,  Jasti, Ramesh  ,  Yamago, Shigeru

26 ( 11 )  , pp.1615 - 1619 , 2015-06-19 , Thieme Publishing Group
A selective, practical, and large-scale synthesis of [6]cycloparaphenylene, the second smallest cycloparaphenylene to be synthesized, was achieved in nine steps starting from commercially available 1, 4-dibromobenzene and 4′-bromobiphenyl-4-ol. The key intermediate, cis-1, 4-(4-bromophenyl)-1, 4-bis(triethylsiloxy)cyclohexa-2, 5-diene, was prepared on a large scale (>20 g) and was selectively dimerized to form a cyclic precursor of [6]cycloparaphenylene by platinum-mediated assembly and subsequent reductive elimination. Deprotection of the triethylsilyl group and subsequent tetrachlorostannic acid (H2SnCl4)-mediated reductive aromatization gave [6]cycloparaphenylene in 23% overall yield from the commercially available substrates on gram scale.

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