Oxidative Functionalisation of SuperQuat Enamides: Asymmetric Synthesis of Homochiral 1,2 Diols
作者:Stephen G. Davies、Min-Suk Key、Humberto Rodriguez-Solla、Hitesh J. Sanganee、Edward D. Savory、Andrew D. Smith
DOI:10.1055/s-2003-41425
日期:——
Homochiral (E)-enamides derived from (S)-4-phenyl-5,5-dimethyl-oxazolidin-2-one undergo highly diastereoselective epoxidation upon treatment with dimethyldioxirane (DMDO). Treatment with m-chloroperbenzoic acid (MCPBA) produces syn-(4S,1′R,2′S)-1′-acyloxy-2′-hydroxy derivatives with high diastereoselectivity, consistent with a mechanism involving initial epoxidation and subsequent in situ SN1 type epoxide opening and trapping with m-chlorobenzoic acid. Reductive cleavage of the isolated 1′-acyloxy-2′-hydroxy derivatives generates 1,2-diols in high yields and in high ee.
衍生自 (S)-4-苯基-5,5-二甲基-恶唑烷-2-酮的同手性 (E)-烯酰胺在用二甲基二环氧乙烷 (DMDO) 处理后会发生高度非对映选择性环氧化。用间氯过苯甲酸 (MCPBA) 处理产生具有高非对映选择性的顺式-(4S,1′R,2′S)-1′-酰氧基-2′-羟基衍生物,这与涉及初始环氧化和随后的原位 SN1 的机制一致用间氯苯甲酸打开和捕获环氧化物。分离的 1'-酰氧基-2'-羟基衍生物的还原裂解以高产率和高 ee 生成 1,2-二醇。