Enantiopure, BINOL-derived diphosphoramidites built upon an achiral hydrazine spacer are efficient ligands for the hydrogenation of 2-(acetylamino)-3-(aryl)-propenoic methyl esters. The activity and enantioselectivity of the hydrazine derivatives were shown to be markedly influenced by the nature of the two NR substituents, symmetrical but bulky R groups leading to the best results. A diphosphosphoramidite obtained from tBuHNNHtBu resulted in ee's as high as 95%. The present results contradict previous reports on “short” diphosphoramidites.
手性纯的基于BINOL的
二膦氨基酰胺,在无手性的
肼间隔上构建,是氢化2-(乙酰
氨基)-3-(芳基)-
丙烯酸甲酯的有效
配体。
肼衍
生物的活性和对映选择性明显受到两个NR取代基性质的影响,对称但庞大的R基团产生最佳效果。从tBuHNNHtBu获得的
二膦氨基酰胺的对映纯度高达95%。目前的结果与之前关于“短”
二膦氨基酰胺的报告相矛盾。