Dihydropyridones: catalytic asymmetric synthesis, N- to C-sulfonyl transfer, and derivatizations.
ABSTRACT 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. These products readily undergo N- to C-sulfonyl photoisomerization and are derivatized to afford stereodefined piperidines and tetrahydropyrans.
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ABSTRACT: An efficient enantioselective approach to form trans lactams and cis lactones in up to 98 % yield with greater than 99 % ee, and greater than 20:1 d.r. using simple aliphatic aldehydes has been developed. The process involves a new pathway to generate enolate intermediates from aliphatic aldehydes by oxidation and deprotonation. NHC=N-heterocyclic carbene, Ts=4-toluenesulfonyl.Angewandte Chemie International Edition 11/2012; · 13.73 Impact Factor