The regio- and stereoselective hydroxylation of variously substituted asymmetric 4a-methyl octalenones by selected fungal strains has been shown to afford, sometimes in high yields, several optically pure derivatives, generally hydroxylated in the B-ring. The potential of this method for the preparation of functionalized (hydroxylated) chiral synthons is evaluated and discussed.
US5430157A
申请人:——
公开号:US5430157A
公开(公告)日:1995-07-04
Stereochemical studies. XLII. Asymmetric synthesis of naturally occurring podocarpic acid.
作者:TAKANORI SONE、SHIRO TERASHIMA、SHUNICHI YAMADA
DOI:10.1248/cpb.24.1288
日期:——
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.