Anti-Selective Aldol Reactions with Titanium Enolates of <i>N</i>-Glycolyloxazolidinethiones
作者:Michael T. Crimmins、Patrick J. McDougall
DOI:10.1021/ol034001i
日期:2003.2.1
addition utilizing a variety of N-glycolyloxazolidinethiones has been developed. Enolization of an N-glycolyloxazolidinethione with titanium (IV) chloride and (-)-sparteine followed by addition of an aldehyde activated with additional TiCl(4) resulted in highly anti-selective aldol additions, typically with no observable syn isomers. Allyl-protected glycolates demonstrated the highest levels of selection
[反应:见正文]已经开发了利用多种N-羟基乙醇酰恶唑烷硫酮的高度非对映选择性抗羟醛加成物。N-乙二醇基恶唑烷硫酮与氯化钛(IV)和(-)-天冬氨酸的烯醇化,然后添加由额外的TiCl(4)活化的醛,可产生高度抗选择性的羟醛添加,通常没有可观察到的同分异构体。烯丙基保护的乙醇酸酯显示出最高的选择和收率水平,尽管O-苄基和O-甲基乙二醇基恶唑烷硫酮也表现良好。