Lithium−Sulfoxide−Lithium Exchange for the Asymmetric Synthesis of Atropisomers under Thermodynamic Control
作者:Jonathan Clayden、David Mitjans、Latifa H. Youssef
DOI:10.1021/ja017702o
日期:2002.5.1
introduces a sulfoxide substituent ortho to the stereogenic Ar-CO axis of an aromatic amide. The sulfoxide exerts a powerful conformational bias on the axis, such that after rapid equilibration at ambient temperature essentially only one of two diastereoisomeric Ar-CO atropisomers is populated. Sulfoxide-lithium exchange by treatment with t-BuLi regenerates the ortholithiated amide in an enantiomerically pure