Synthesis of a Pillar[5]arene-Based [2]Rotaxane with Two Equivalent Stations via Copper(I)-Catalyzed Alkyne–Azide Cycloaddition

A one-pot synthesis of pillar[5]­arene-based [2]­rotaxanes containing one and two stations by copper­(I)-catalyzed alkyne–azide cycloaddition (CuAAC) reaction is reported. In situ formation of the two stations by two stepwise CuAAC reactions allows for the synthesis of a [2]­rotaxane containing two stations with equal energy levels that exhibit shuttling of the pillar[5]­arene wheel

Clickable Di- and Tetrafunctionalized Pillar[<i>n</i>]arenes (<i>n</i> = 5, 6) by Oxidation–Reduction of Pillar[<i>n</i>]arene Units

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

Clickable Di- and Tetrafunctionalized Pillar[<i>n</i>]arenes (<i>n</i> = 5, 6) by Oxidation–Reduction of Pillar[<i>n</i>]arene Units

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