Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu, 610064, P. R. China.
Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, P. R. China.
Chemistry. 2018 Sep 12;24(51):13428-13431. doi: 10.1002/chem.201803507. Epub 2018 Aug 17.
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) 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 (>19:1 d.r., 90-96 % ee). A possible transition state model was proposed to elucidate the origin of chiral induction based on the control experiments and X-ray crystal structure of the catalyst.
在手性 N,N'-二氧杂环戊烷/Mg(OTf)2 配合物的存在下，通过去对称化/环合过程，实现了降蒈酮或氮杂庚三烯与内消旋氮丙啶的高对映选择性[8+3]高阶环加成反应。相应的四氢环庚[b][1,4]恶嗪和四氢-1H-环庚[b]-吡嗪以良好的收率（66-98%）和优异的非对映选择性和对映选择性（>19:1 d.r.，90-96%ee）获得。根据控制实验和催化剂的 X 射线晶体结构，提出了一个可能的过渡态模型，以阐明手性诱导的起源。
