Organic Chemistry Department, University of Geneva, quai Ernest Ansermet 30, 1211 Genève 4, Switzerland.
Chemistry. 2010 Mar 1;16(9):2797-805. doi: 10.1002/chem.200902562.
Three tricyclic diquats with an eight-membered ring were prepared and shown to be the first configurationally stable derivatives of their kind. Resolution was achieved by using chiral hexacoordinated phosphorus BINPHAT and TRISPHAT anions. The diquat cations were obtained in high diastereo- and enantiomeric purity (ee>96% in most cases). X-ray diffraction analysis coupled with circular dichroism (CD) measurements allowed a precise determination of the relative and absolute configuration of the salts. The barriers to racemization of these compounds were calculated by using CD time-course measurements at different temperatures, affording DeltaG(++) values above 25 kcal mol(-1). Derivatives 4a, 4b, and 4c are the first eight-membered-ring derivatives with only three ring constraints to be resolved. This manuscript also reports the first procedure to remove TRISPHAT anions after diastereomeric separation.
三种具有八元环的三环二价阳离子被制备出来，并被证明是同类结构中第一个构型稳定的衍生物。通过使用手性六配位磷BINPHAT 和 TRISPHAT 阴离子实现了对映选择性拆分。二价阳离子以高非对映和对映体纯度（在大多数情况下，ee 值>96%）获得。X 射线衍射分析结合圆二色性（CD）测量允许对盐的相对和绝对构型进行精确确定。通过在不同温度下进行 CD 时程测量计算这些化合物的外消旋化势垒，得到了 DeltaG(++) 值高于 25 kcal mol(-1)。衍生物 4a、4b 和 4c 是第一个仅具有三个环约束的八元环衍生物，并且可以拆分。本文还报道了在非对映选择性分离后去除 TRISPHAT 阴离子的第一个程序。
