Categories: Synthesis of N-Heterocycles, Synthesis of O-Heterocycles > benzo-fused N-Heterocycles, benzo-fused O-Heterocycles >
Synthesis of 3,4-Dihydro-2H-1,4-benzoxazines
Recent Literature
An efficient synthesis of 3,4-dihydro-1,4-benzoxazine derivatives in excellent
enantio- and diastereospecificity (ee > 99%, de > 99%) proceeds via Lewis
acid-catalyzed SN2-type ring opening of activated aziridines with
2-halophenols followed by Cu(I)-catalyzed intramolecular C-N cyclization in a
stepwise fashion.
A. Mal, I. A. Wani, G. Goswami, M. K. Ghorai, J. Org. Chem., 2018, 83,
7907-7918.
The use of the chiral bisphosphorus ligand WingPhos enables a versatile,
regio- and enantioselective palladium-catalyzed tandem allylic substitution to
provide a series of chiral vinyl-substituted heterocycles, including
tetrahydroquinoxalines, piperazines, dihydro-2H-benzo[b][1,4]-oxazines,
and morpholines, in exellent ees and yields. The protocol features mild reaction
conditions.
C. Qian, W. Tang,
Org. Lett., 2020, 22, 4467-4470.
A chiral phosphoric acid (CPA) catalyzes a versatile transition metal/oxidant
free synthesis of chiral 2H-1,4-benzoxazines through enantioselective
desymmetrization of prochiral oxetanes (30 examples) in very good yield and high
enantioselectivity under mild reaction conditions.
V. A. Bhosale, M. Nigríni, M. Dračínský, I. Císařová, J. Veselý, Org. Lett., 2021, 23,
9376-9381.