A General Approach to (5<i>S</i>,6<i>R</i>)-6-Alkyl-5-benzyloxy-2-piperidinones: Application to the Asymmetric Syntheses of Neurokinin Substance P Receptor Antagonist (−)-L-733,061 and (−)-Deoxocassine
A generalapproach to (5S,6R)-6-alkyl-5-benzyloxy-2-piperidinones based on the regio- and diastereoselective reductive alkylation of (S)-3-benzyloxyglutarimide 7 is described. This method opens an entrance to chiral nonracemic substituted 3-piperidinols. The versatility of the method is illustrated by the asymmetric syntheses of neurokinin substance P receptor antagonist L-733,061 (ent-1), (−)-deoxocassine