作者:Ryukichi Takagi、Asami Sasaoka、Satoshi Kojima、Katsuo Ohkata
DOI:10.1039/a704563h
日期:——
The stereoselective synthesis of rac- and ent-rhopaloic acid A 1 has been accomplished, via successive homologation of (2E,6E)-farnesol 2 and cyclization to form a tetrahydropyran ring, together with final introduction of an α-methylene group; the asymmetric synthesis was achieved via an Evans’ asymmetric alkylation using (S)-4-benzyloxazolidin-2-one as a chiral auxiliary; the synthetic rhopaloic acid A, with a predicted absolute configuration of (2S,5R), had a specific rotation of opposite sign to that of the natural product, and therefore the configuration of natural rhopaloic acid A should be assigned as (2R,5S).
对消旋和反消旋的立体选择合成了蕈酸A 1,方法包括对(2E,6E)-法尼醇2的连续同源化以及环化形成四氢吡喃环,最后引入α-亚甲基基团;不对称合成通过使用(S)-4-苄氧杂环丁酮作为手性辅助体实现;合成的蕈酸A,其预测的绝对构型为(2S,5R),其特定旋光度与天然产物相反,因此天然蕈酸A的构型应当被确定为(2R,5S)。