Diastereoface-discrimination reaction of lithium or titanium ester enolates with a chiral imine leading to stereodivergent synthesis of β-lactams
作者:Tamotsu Fujisawa、Yutaka Ukaji、Tomohiro Noro、Kengo Date、Makoto Shimizu
DOI:10.1016/0040-4020(92)80013-6
日期:1992.7
Diastereoselective addition reaction of ester enolates to a chiral imine possessing (4S, 5S)-4,5-dimethoxymethyl-2-methyl-1,3-dioxolane ring as a chiral auxiliary is reported, in which varying metal enolates resulted in the selective formation of (4S)- or (4R)-β-lactam. Namely, addition of the lithium enolates provided (4S)-β-lactams, whereas the triisopropoxytitanium enolates effected selective formation
据报道,酯烯酸酯与具有(4 S,5 S)-4,5-二甲氧基甲基-2-甲基-1,3-二氧戊环作为手性助剂的手性亚胺的非对映选择性加成反应,其中各种金属烯酸酯导致选择性形成(4 S)-或(4 R)-β-内酰胺。即,添加烯醇锂提供了(4 S)-β-内酰胺,而三异丙氧基钛烯醇盐实现了选择性形成(4 R)-β-内酰胺,证明了一个成功的例子,其中钛酸酯烯醇盐用于与亚胺。可能的中间体导致(4 S)-和(4 R还讨论了异构体,并假定了钛和锂金属与手性助剂的不同配位能力以反映选择性的逆转。