4. Chelate-controlled asymmetric synthesis of 2-substituted 2,3-dihydropyridin-4(1H)-ones: Synthesis of D- and L-aminodeoxyaltrose derivatives

Article abstract of DOI:10.1002/hlca.19950780106

Asymmetric methylation and phenylation of the chiral pyridinium salt 7, as well as methylation of chiral pyridinium salt 18, with Grignard reagents occurred in good yield and with good-to-excellent diastereoselectivities. These results are best explained by assuming chelate control to govern the asymmetric alkylation/arylation process. The minimum-energy conformations of the out-of-plane twisted pyridinium salts 7 and 18, as determined hy the 'Molecular Simulations Cerius-Dreiding II' program, are in good agreement with the postulated asymmetric chelate-control mechanism.