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Solid-phase Synthesis of [4.4] Spirocyclic Oximes
Published on: February 6, 2019
Borepin Rings as "Sigma-Free" Reporters of Aromaticity within Polycyclic Aromatic Scaffolds
Reid E Messersmith1, John D Tovar1,2
1Department of Chemistry , Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States of America.
Abstract:
The definition and measurement of local and global aromaticity in fused ring polycyclic aromatic compounds is a complex issue. Historically, these types of molecules have been explored in this capacity by way of experimental (NMR, thermochemistry) and computational (NICS, HOMA) analyses. We previously showed how borepin rings with [ b, f] arene fusions can be used as experimental magnetic aromaticity reporters via the remaining protons attached to the borepin rings. In this report, we describe a joint experimental and computational analysis of several borepin-containing polycyclic aromatic molecules in order to draw conclusions about the influence of ring fusion on aromaticity. We find that the borepin ring within these extended structures is a unique motif with limited σ-contribution to aromaticity while still displaying a wide range of structural and magnetic aromatic character.
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