A highly enantioselectivecatalytic protocol for the desymmetrization of meso-aziridines via ring-opening with pyrazoles is reported using an N,N′-dioxide-Mg(OTf)2 complex as the catalyst. The corresponding trans-α-pyrazole-substituted amines were obtained in good yields and enantioselectivities (up to 99% yield and 94% ee) under mild reaction conditions. Moreover, a remarkably high asymmetric amplification
The asymmetric ring-opening of meso-aziridines with primary alcohols is realized using an N,N′-dioxide–Mg(OTf)2 complex as the catalyst. The desired vicinal trans-β-amino ethers are afforded in good yields and enantioselectivities. Aniline and water could also be used as the nucleophiles for the ring-opening in an identical catalyst system.
Highly enantioselective [8+3] high‐order cycloaddition reactions of tropones or azaheptafulvenes with meso‐aziridines were achieved by a desymmetrization/annulation process in the presence of chiral N,N′‐dioxide/Mg(OTf)2 complex. The corresponding tetrahydrocyclohepta[b][1,4]oxazines and tetrahydro‐1H‐cyclohepta‐ [b]‐pyrazines were obtained in good yields (66–98 %) with excellent diastereo‐ and enantioselectivities
在手性N,N'-二氧化物/ Mg(OTf)2络合物存在下,通过去对称/环化过程实现了对偶氮酮或氮杂庚烯酮与内消旋氮杂环丁烷的高度对映选择性[8 + 3]高阶环加成反应。相应的四氢环庚[ b ] [1,4]恶嗪和四氢-1 H-环庚[[ b ]-吡嗪类化合物以良好的非对映和对映选择性(> 19:1 dr,90)获得了良好的收率(66-98%)。 –96%ee)。根据控制实验和催化剂的X射线晶体结构,提出了一种可能的过渡态模型,以阐明手性诱导的起源。