Starting from iodoalcohol 9, the monoprotected dialdehyde 5 was synthesized (Scheme 2) and converted to 17 by reaction with oxo-phosphonate 15 (Scheme 3). The latter was prepared from 13. Cyclisation of 17 to the target compound 18 failed. Also the attachment of thiol 22 to lactone 19 was unsatisfactory (Scheme 4). Therefore, the building blocks 28 and 29 were synthesized using diene 33 and diester
从
碘醇9开始,合成了单保护的二醛5(方案2),并通过与氧代
膦酸酯15的反应转化为17(方案3)。后者是从13准备的。17环化为目标化合物18失败。同样,
硫醇22与内酯19的连接也不令人满意(方案4)。因此,使用二烯33和二酯30作为起始原料合成了构建基块28和29。28和9表示29(方案5和6)。羟基酸28被转化成甲酰基酯46(方案7)。然而,其衍
生物48和49与羰基反应性的“ Umpolung”的缩合是不成功的,这可能是由于空间位阻。