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Published on: May 21, 2019
Biphenyl Cyclobutenone Photoelectrocyclizations
Changhang Dai1, Xuchen Zhao1, Changqing Song1
1Department of Chemistry, University of Utah, 315 South, 1400 East, Salt Lake City, Utah 84112, United States.
Abstract:
In this work, we demonstrate that readily available conjugated bis-aryl cyclobutenones undergo photoelectrocyclization reactions to give the corresponding dihydrophenanthrene cyclobutanones when exposed to 350 nm light, TFA, and TMSCl. We have also found that cyclobutenone electrocyclizations and cycloreversions are in equilibrium.
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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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