Dihydropyridones: Catalytic Asymmetric Synthesis, N‐ to C‐Sulfonyl Transfer, and Derivatizations

Benzotetramisole (1) promotes the reaction of ammonium enolates derived from arylacetic acids with N-tosyl-α,β-unsaturated ketimines, thus giving dihydropyridones with high diastereo- and enantiocontrol (see scheme). These products readily undergo N- to C-sulfonyl photoisomerization and are derivatized to afford stereodefined piperidines and tetrahydropyrans.