ORGN 673 |
Enantioselective total synthesis of (+)-Rogioloxepane A
| Michael T. Crimmins and Amy C. DeBaillie. Department of Chemistry, University of North Carolina at Chapel Hill, Venable and Kenan Laboratories of Chemistry, CB# 3290, Chapel Hill, NC 27599 |
The total synthesis of (+)-Rogioloxepane A will be presented. Rogioloxepane A was isolated in 1992 from the red seaweed Laurencia microladia collected in the Mediterranean Sea off the torrent II Rogiolo. Rogioloxepane A is a seven membered oxepene ring with a,a'-trans-disubstitution, two halogen substituents, and a terminal Z enyne moiety. The synthetic strategy involves the use of a Sharpless kinetic resolution of racemic allylic alcohol 4 to set the stereogenic centers at C12 and C13. An asymmetric glycolate alkylation was utilized to form 3, which was subjected to ring-closing metathesis conditions to construct the a,a'-trans-disubstituted core. The stereogenic center at C6 was installed via a diastereoselective acetate aldol to aldehyde 2. The total synthesis was accomplished in twenty-one overall chemical steps. |
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