Enantiospecific Synthesis of the (9S,18R)-Diastereomer of the Leukocyte Adhesion Inhibitor Cyclamenol A
作者:Marc Nazaré、Herbert Waldmann
DOI:10.1002/1521-3765(20010803)7:15<3363::aid-chem3363>3.0.co;2-y
日期:2001.8.3
enantioselective total synthesis of the (9S, 18R)-diastereomer of this macrocyclic polyene lactam. Key elements of the synthesis are i) the synthesis of the required chiral building blocks by employing readily accessible building blocks from the chiral pool, that is, (S)-malic acid and (R)-hydroxyisobutyric acid, ii) assembly of a linear polyene precursor by means of Wittig and Horner olefination reactions as
仙客来酚A是极少数的抑制白细胞粘附于内皮细胞的非碳水化合物和非肽类天然产物之一。我们报道了该大环多烯内酰胺的(9S,18R)-非对映异构体的第一个对映选择性全合成。合成的关键要素是:i)通过从手性池中容易获得的结构单元,即(S)-苹果酸和(R)-羟基异丁酸,合成所需的手性结构单元,ii)线性组装Wittig和Horner烯化反应将多烯前体作为关键的CC键形成转化,iii)通过钒介导的频烷醇化反应进行闭环,iv)将生成的顺式二醇转化为(Z)-烯烃以完成天然产物的整个多烯体系。通过McMurry反应中的大内酰胺化,双Stille偶联或直接烯烃化来封闭大环的尝试失败。成功完成合成的关键是最终步骤的正确编排。必须首先使形成大环的中间体脱保护,并在最后一步借助科里-霍普金斯序列生成灵敏的庚烯系统。