You-Qing Wang, Xiao-Yu Cui, Yuan-Yuan Ren and Yongna Zhang
Org. Biomol. Chem., 2014,12, 9101-9104
DOI:
10.1039/C4OB01902D,
Communication
A highly enantioselective direct Mannich reaction of methyl alkyl ketones with cyclic imines benzo[e][1,2,3]oxathiazine 2,2-dioxides, catalyzed by the combination of cinchona alkaloid derived primary amine and TFA, is disclosed. For unsymmetrical methyl alkyl ketones, it is favoured that specific regioselective addition to the imine substrates occurs at the less-substituted methyl group by steric control.