Categories: Synthesis of N-Heterocycles >
Synthesis of azepines
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.
M. J. Mailloux, G. S. Fleming, S. S. Kumta, A. B. Beeler, Org. Lett., 2021, 23, 525-529.
Polyethylene glycol (PEG) is an inexpensive nontoxic and effective medium for the one-pot synthesis of N-substituted azepines under catalyst-free conditions in excellent yields. Environmental acceptability, low cost, high yields, and recyclability of the PEG are the important features of this protocol.
R. Mallepalli, L. Yeramanchi, R. Bantu, L. Nagarpu, Synlett, 2011, 2730-2732.