Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark.
Chemistry. 2020 Sep 4;26(50):11417-11422. doi: 10.1002/chem.202001369. Epub 2020 Aug 4.
Organocatalytic enantioselective 1,3-dipolar [6+4] cycloadditions of pyrylium ion intermediates with fulvenes promoted by a chiral primary amine catalyst have been developed to proceed in moderate to good yields and high enantioselectivities. The resultant chiral bicyclo[6.3.0]undecane scaffold containing a transannular bridging ether is densely functionalised providing a rigid scaffold for further manipulations. Computational studies give important insights into the role of the primary amine catalyst. Analysis of the reaction shows that the catalytic reaction proceeds in a step-wise manner and rationalises the stereochemical outcome of the reaction. Several stereoselective complexity-generating transformations, facilitated by the diverse functional groups and transannular bridge, are presented, highlighting the versatility of the core towards a number of the cyclooctanoid natural products.
手性伯胺催化的吡喃鎓离子中间体与富烯的对映选择性 1,3-偶极环加成反应已被开发出来，可在中等至良好的收率和高对映选择性下进行。所得的含有反式桥接醚的手性双环[6.3.0]十一烷骨架得到了高度官能化，为进一步的操作提供了刚性骨架。计算研究为手性伯胺催化剂的作用提供了重要的见解。反应分析表明，催化反应是分步进行的，并合理地解释了反应的立体化学结果。通过各种功能基团和反式桥的促进，呈现了几种立体选择性的复杂生成转化，突出了该核心对许多环辛烷天然产物的多功能性。
