Stereodivergency in Catalytic Asymmetric Conjugate Addition Reactions of Glycine (Ket)imines

Stereodivergent catalytic asymmetric conjugate reactions of glycine (ket)­imines with nitroalkenes have been achieved using various chiral catalyst systems derived from a multidentate amino alcohol (1). The stepwise nature of the [3 + 2] cycloaddition reactions of N-metalated azomethine ylides has also been demonstrated by highly enantio- and diastereoselective syntheses of exo-5 and endo-8 from the respective syn-4 and anti-7 conjugate addition products in a one-pot tandem fashion.本研究利用由多齿氨基醇(1)衍生得到的多种手性催化剂体系，成功完成了甘氨酸酮亚胺(glycine ketimines)与硝基烯烃(nitroalkenes)的立体发散型催化不对称共轭反应。此外，通过一锅串联策略，由对应的syn-4与anti-7共轭加成产物高对映选择性、高非对映选择性地合成外型-5与内型-8，这一结果证实了N-金属化甲亚胺叶立德(N-metalated azomethine ylides)的[3+2]环加成([3 + 2] cycloaddition)反应具有分步特性。