Enantioselective Aza-Henry Reactions Assisted by Zn(II) and N-Methylephedrine

Significance

The aza-Henry reaction has been widely studied and other asymmetric variants do exist. This protocol is very significant in that the chiral source is the commercially available N-meth­ylephedrine (NME) and the nitrogen-protecting group is the useful Boc group. The authors found that the use of a base is vital for the reaction, but the particular base used did not matter (various tertiary amines gave acceptable results). Aryl groups with electron-withdrawing groups gave slightly lower enantiomeric excesses than those with electron-donating groups.