Silver/ThioClickFerrophos-Catalyzed Enantioselective Conjugate Addition and Cycloaddition of Glycine Imino Ester with Nitroalkenes

We applied the combination of AgOAc with ThioClickFerrophos, the chiral ferrocenyl triazole-based P,S-ligand, to the reaction of glycine imino ester with nitroalkenes. The conjugate addition of the imino methyl ester preferentially produced anti-α-imino-γ-nitrobutyrates in good yields with high enantioselectivities (ee) of up to 99% at −25 °C in THF in the presence of triethylamine. Meanwhile, the pyrrolidine cycloadducts were obtained as major products in good yields with high enantioselectivities (up to 96% ee) using tert-butyl imino ester in the absence of triethylamine at room temperature.

我们将乙酸银（AgOAc）与手性二茂铁基三唑类P,S配体ThioClickFerrophos复配使用，应用于甘氨酸亚氨基酯与硝基烯烃的加成反应。在三乙胺存在、四氢呋喃（THF）溶剂中于-25 ℃条件下，亚氨基甲酯的共轭加成反应优先生成反式-α-亚氨基-γ-硝基丁酸酯，产物产率良好，对映选择性优异，对映体过量值（ee）最高可达99%。而在不添加三乙胺的室温条件下，以亚氨基叔丁酯为底物时，主要得到吡咯烷环加成产物，其产率良好且对映选择性优异，对映体过量值最高可达96% ee。