Optically enriched Hantzsch dihydropyridines
bearing
different
ester groups were obtained through the asymmetric catalytic cascade
reaction between 3-amino-2-butenoates and (Z)-2-arylidene-3-oxobutanoates.
The N,N′-dioxide/NiII or NdIII complex catalysts were disclosed to be efficient,
furnishing a variety of the products, including drugs like nitrendipine,
nimodipine, and felodipine, in high yields (up to 99% yield) with
excellent enantioselectivities (up to 99% ee). Two enantiomers of
the products can be obtained readily via exchange of the ester group
of the two reactants. In addition, axial chiral 4-arylpyridines were
also afforded through an oxidation process.