Kuehne M E, Dai W, Li Y L
Department of Chemistry, University of Vermont, Burlington, VT 05405, USA.
J Org Chem. 2001 Mar 9;66(5):1560-6. doi: 10.1021/jo001399c.
(+)-(R)-1,2-(alpha-(R)-Mesyloxy-beta-dimethyltetramethylene)-ferrocene was synthesized and used as a chiral auxiliary for N-alkylation of methyl 1,2,3,4,5,6-hexahydroazepino[4,5-b] indole-5-xi-carboxylates. Condensation with aldehydes then provided tetracyclic products in a diastereomeric ratio of at least 97:3. Gentle cleavage in acetic acid removed the chiral auxiliary to give the corresponding secondary amines in >99% ee. Thus, key intermediates leading to mossambine and vinblastine could be synthesized with high enantioselectivity. The enantioselectivity greatly exceeds that found with other chiral N-auxiliaries developed in our studies.
合成了(+)-(R)-1,2-(α-(R)-甲磺酰氧基-β-二甲基四亚甲基)-二茂铁，并将其用作1,2,3,4,5,6-六氢氮杂环庚烷并[4,5-b]吲哚-5-羧酸甲酯N-烷基化反应的手性助剂。随后与醛进行缩合反应，以至少97:3的非对映体比例得到四环产物。在乙酸中温和裂解除去手性助剂，得到对映体过量值>99%的相应仲胺。因此，可以高对映选择性地合成导致莫桑比宁和长春碱的关键中间体。该对映选择性大大超过了我们研究中开发的其他手性N-助剂的对映选择性。
