Abstract
Optically active methyl deoxypodocarpate ((S) (+)-5b), 92% optically pure, was synthesized from (R) (+)-δ-ketoaldehyde ((R) (-)-3a) which was obtainable by the asymmetric synthesis using D-proline-derived pyrrolidine ((R)-4 (R2=CH2NC4H3)) as a chiral additive. The chemical scheme which was previously developed, was used for the conversion of (R) (-)-3a to (S) (+)-phenanthrone derivative ((S) (+)-1a), and a combination of reductive carbomethoxylation and reductive alkylation was adopted for preparing (S) (+)-5b from (S) (+)-1a. Since (S) (+)-5b had already been converted to naturally occurring podocarpic acid ((S) (+)-5a), the asymmetric synthesis of (S) (+)-5a was accomplished.
