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[DPEPhosbcpCu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst
Published on: May 21, 2019
A Base-Mediated Rearrangement of the Benzylic 1,5-Hexadipyridynyl Moiety
Wouter A Remmerswaal1,2, Thai-Tony Nguyen1,2, Han Zijan3
1Department of Chemistry - BMC, Uppsala University, 751 23, Uppsala, Sweden.
Abstract:
A previously unrecognized base-mediated rearrangement of a benzylic 1,5-hexadipyridynyl moiety is reported. Upon exposure to base, this structural motif rearranges into a constrained vinyl-pyridine substituted cyclobutene. Computational modeling indicates that the rearrangement takes place following a route involving stepwise deprotonation, shifted reprotonation, and 4π-electrocyclization. The reaction rate and the stereochemical outcome is consistent with the experimental observations. Furthermore, nonbase mediates rearrangements, through well-known Cope-like [3,3]-sigmatropic shifts, are found to be high in energy, and therefore, take a backseat to the base-mediated pathway. This rearrangement may provide a novel reactivity pathway of conjugated systems for synthetic methodology development.
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