title: Clickable di- and tetrafunctionalized pillar[n]arenes (n = 5, 6) by oxidation-reduction of pillar[n]arene units.
abstract: We report a new route for the selective synthesis of di- and tetrafunctionalized pillararenes via oxidation and reduction of the pillararene units. Hypervalent-iodine oxidation of perethylated pillar[5]arene afforded pillar[5]arene derivatives containing one benzoquinone unit and two benzoquinones at the A,B- and A,C-units. A pillar[6]arene derivative containing one benzoquinone unit was also synthesized. Reduction of the benzoquinone units yielded position-selective di- and tetrahydroxylated pillararene derivatives. This methodology avoids the generation of many constitutional isomers and overcomes the isolation problem of numerous constitutional isomers. From these hydroxylated pillararenes, Huisgen reaction-based clickable di- and tetraalkynylated pillar[5]arenes were prepared. Because of the highly selective and reactive nature of Huisgen alkyne-azide cycloaddition, these pillar[5]arenes can serve as key compounds for a large library of di- and tetrafunctionalized pillararenes. Based on these di- and tetrafunctionalized pillar[5]arenes as key compounds, fluorescent sensors were created by the modification of di- and tetrapyrene moieties via Huisgen-type click reactions.
authors.affiliation: Department of Chemistry and Chemical Engineering, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan. ogoshi@t.kanazawa-u.ac.jp
authors.forename: Tomoki
authors.initials: T
authors.lastname: Ogoshi
authors.forename: Daiki
authors.initials: D
authors.lastname: Yamafuji
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kotera
authors.forename: Takamichi
authors.initials: T
authors.lastname: Aoki
authors.forename: Shuhei
authors.initials: S
authors.lastname: Fujinami
authors.forename: Tada-aki
authors.initials: TA
authors.lastname: Yamagishi