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Published on: May 21, 2019
Reversing the stereoselectivity of intramolecular [2+2] photocycloaddition utilizing cucurbit[8]uril as a molecular
Xujun Qiu1, Jasmin Seibert1, Olaf Fuhr2,3
1Institute of Organic Chemistry (IOC), Karlsruhe Institute of Technology (KIT), Kaiserstraße 12, 76131 Karlsruhe, Germany. braese@kit.edu.
Abstract:
Macrocyclic hosts, such as cucurbit[8]uril (CB8), can significantly influence the outcomes of chemical reactions involving encapsulated reactive guests. In this study, we demonstrate that CB8 completely reverses the stereoselectivity of intramolecular [2+2] photo-cycloaddition reactions. Notably, it was also found that CB8 can trigger the unreactive diene to be reactive.
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Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.

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