Department of Organic Chemistry, Indian Institute of Science, Bangalore-560012, India.
Centre for Materials Characterization, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India.
Org Lett. 2020 Jul 17;22(14):5407-5411. doi: 10.1021/acs.orglett.0c01756. Epub 2020 Jul 1.
The NHC-catalyzed desymmetrization of cyclic-1,3-diketones allowing the enantioselective construction of tricyclic β-lactones with five contiguous stereocenters, including two quaternary stereocenters, has been developed. The mild and operationally simple addition of α-bromoenals to cyclopentane-1,3-diketone derivatives proceeds via the initial formation of chiral α,β-unsaturated acylazolium intermediates and culminates in a cascade reaction, following the Michael-aldol-lactonization pathway to deliver the β-lactone derivatives in moderate to good yields and excellent selectivity.
NHC 催化的环状 1,3-二酮的非对映选择性拆分，允许通过五元稠合的立体中心，包括两个季碳立体中心的手性三环 β-内酰胺的对映选择性构建，已经被开发出来。通过初始形成手性 α,β-不饱和酰基氮唑中间体，温和且操作简单地将 α-溴代烯醛添加到环戊烷-1,3-二酮衍生物中，然后通过迈克尔-羟醛-内酯化途径进行级联反应，以中等至良好的收率和优异的选择性得到β-内酰胺衍生物。
