Asymmetric Synthesis of (-)-Indolizidine167B and (+)-Coniine

The enantioselective syntheses of (-)-indolizidine 167B and (+)-coniine were described based on the asymmetric hydrogenation of racemic d-hydroxy esters via kinetic resolution. With optically active chiral d-hydroxy ester (S)-4 and chiral 1,5-diol (R)-5 obtained by asymmetric hydrogenation of racemic ethyl 5-hydroxyoctanoate (rac-4) with chiral spiro iridium catalyst Ir-(R)-SpiroPAP as chiral starting materials, the efficient enantioselective syntheses of (-)-indolizidine 167B and (+)-coniine were achieved by using intramolecular reductive amination and N-substitution/cyclization, respectively, as a key step to construct the chiral aza-bicyclic[4.3.0]nonane skeleton and chiral piperidine ring. This provides new efficient methods for enantioselective syntheses of indolizidine and piperidine alkaloids.y