Dual-Organocatalyst-Promoted Asymmetric Cascade Reaction: Highly Efficient Construction of Enantiopure Fully Substituted Tetrahydro-1,2-oxazines

A four-component
asymmetric α-aminoxylation/aza-Michael/Mannich
cascade
reaction for the construction of fully substituted chiral tetrahydro-1,2-oxazine
derivatives was accomplished in high yields with excellent enantio-
and diastereoselectivities under mild conditions. The 1,2-oxazine
derivative could be transformed to the corresponding multifunctional
chiral amino alcohol by N–O cleavage and fused-tricyclic 4-amino-substituted
tetra­hydro­quino­lines in good yields with excellent
stereoselectivities followed by a Friedel–Crafts reaction.
Also a 4-alkoxy-substituted tetra­hydro­quino­line
was achieved by C-4 inversion of a 4-amino-substituted tetra­hydro­quino­line.