Preparation and Reactions of Enantiomerically Pure α-Functionalized Grignard Reagents
作者:Peter J. Rayner、Peter O’Brien、Richard A. J. Horan
DOI:10.1021/ja4033956
日期:2013.5.29
without the use of (-)-sparteine as the chiral ligand. Two additional discoveries are noteworthy: (i) for the deprotonation and trapping with Andersen's sulfinate, there is a lack of stereospecificity at sulfur due to attack of a lithiated intermediate onto the α-alkoxy and α-amino sulfoxides as they form, and (ii) the α-alkoxy-substituted Grignard reagent is configurationally stable at room temperature
提出了一种生成对映异构纯 α-官能化手性格氏试剂的策略。该方法涉及通过不对称去质子化(s-BuLi/手性二胺)和安徒生亚磺酸盐(薄荷醇衍生)以≥99:1 dr和≥99:1 er合成α-烷氧基和α-氨基亚砜。随后的亚砜 → Mg 交换(室温,1 分钟)和亲电捕获提供了一系列对映异构纯的 α-烷氧基和 α-氨基取代产物。使用这种方法,在不使用 (-)-sparteine 作为手性配体的情况下,可以从不对称去质子化方案中以 99:1 er 访问产物的任一对映异构体。另外两个发现值得注意:(i) 去质子化和用安徒生亚磺酸盐捕获,