Atropisomeric Properties of 7-, 8-, and 9-Membered-Ring Dibenzolactams: Conformation, Thermal Stability, and Chemical Reactivity
Atropisomeric Properties of 7-, 8-, and 9-Membered-Ring Dibenzolactams: Conformation, Thermal Stability, and Chemical Reactivity
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DOI：
10.1021/jo1013383
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发表时间：
2010-09-03
影响因子：
3.6
通讯作者：
Natsugari, Hideaki
中科院分区：
文献类型：
--
作者：
Tabata, Hidetsugu;Suzuki, Hiroyuki;Natsugari, Hideaki
用手性H-PLC分离了7-、8-和9-元环二苯并内酰胺的阿托品对映体，并用X-射线单晶分析确定了它们的立体化学结构。阿托品具有较高的立体化学稳定性，其中8元环最稳定。在7元和8元二苯并内酰胺中，高度立体选择性的C7-甲基化从环的下侧进行，以提供伪轴向的C7-甲基，该产物转化为热力学上更稳定的与假赤道C7-甲基的异构体。在9元二苯并内酰胺中，C7-甲基化发生在环的相反(上)侧，以提供具有假赤道C7-甲基的热力学稳定的产物。
The atropisomeric enantiomers of 7-, 8-, and 9-membered-ring dibenzolactams were separated by using chiral H PLC, and their stereochemistries were clarified by using X-ray crystallographic analysis. The atropisomers showed high stereochemical stability with the 8-membered ring being the most stable. In 7- and 8-membered dibenzolactams, highly stereoselective C7-methylation proceeded from the lower side of the ring to provide the products with a C7-methyl group in the pseudoaxial orientation, which converted to thermodynamically more stable isomers with the pseudoequatorial C7-methyl group. In 9-membered dibenzolactam, C7-methylation occurred from the opposite (upper) side of the ring to provide a thermodynamically stable product with the pseudoequatorial C7-methyl group.