Couladouros Elias A, Vidali Veroniki P
Chemistry Laboratories, Agricultural University of Athens, Iera Odos 75, Athens 118 55, Greece.
Chemistry. 2004 Aug 6;10(15):3822-35. doi: 10.1002/chem.200400407.
A new stereocontrolled method for the formation of trans-anti cyclogeranyl-oxepene systems is described. The demanding stereochemistry is secured by stereoselective coupling of a cyclogeranyl tertiary alcohol with a 1,2-unsymmetrically substituted epoxide, while the formation of the highly strained oxepene is achieved employing ring-closing metathesis. Since the stereochemistry of the trans-fused 6,7-ring system is determined by the epoxide, the method also allows the construction of trans-syn 6,7-ring systems. This approach leads to the synthesis of the AB fragment of Adociasulfate-2 and Toxicol A, for the first time. The flexibility and efficiency of the presented strategy is demonstrated by the total asymmetric synthesis of (-)-Aplysistatin, (+)-Palisadin A, (+)-12-hydroxy-Palisadin B, and (+)-Palisadin B, employing two similar key intermediates.
描述了一种用于形成反式-反式环香叶基-氧杂环庚三烯体系的新的立体控制方法。通过环香叶基叔醇与1,2-不对称取代的环氧化物的立体选择性偶联确保了苛刻的立体化学，而通过闭环复分解实现了高张力氧杂环庚三烯的形成。由于反式稠合的6,7-环体系的立体化学由环氧化物决定，该方法还允许构建反式-顺式6,7-环体系。这种方法首次实现了阿多西硫酸盐-2和毒理学A的AB片段的合成。通过使用两个相似的关键中间体对(-)-海兔素、(+)-帕利萨丁A、(+)-12-羟基-帕利萨丁B和(+)-帕利萨丁B进行全不对称合成，证明了所提出策略的灵活性和效率。
