Unified Synthesis of Azepines by Visible-Light-Mediated Dearomative Ring Expansion of Aromatic N-Ylides
Matthew J. Mailloux, Gabrielle S. Fleming, Shruti S. Kumta and Aaron B. Beeler*
*Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States, Email: beelerabu.edu
M. J. Mailloux, G. S. Fleming, S. S. Kumta, A. B. Beeler, Org. Lett., 2021, 23, 525-529.
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Deprotonation of quaternary aromatic salts with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or N,N,N',N'-tetramethylquanidine (TMG) under visible light irradiation followed by ring-expansion provides mono- and polycyclic functionalized azepines in very good yields. This dearomative photochemical rearrangement uses two straightforward steps and simple starting materials.
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azepines, photochemistry, flow chemistry