Scope and Mechanism for Lewis Acid-Catalyzed Cycloadditions of Aldehydes and Donor−Acceptor Cyclopropanes: Evidence for a Stereospecific Intimate Ion Pair Pathway
作者:Patrick D. Pohlhaus、Shanina D. Sanders、Andrew T. Parsons、Wei Li、Jeffrey S. Johnson
DOI:10.1021/ja8015928
日期:2008.7.1
In this work, the one-step diastereoselective synthesis of cis-2,5-disubstituted tetrahydrofurans via Lewis acid catalyzed [3 + 2] cycloadditions of donor-acceptor (D-A) cyclopropanes and aldehydes is described. The scope and limitations with respect to both reaction partners are provided. A detailed examination of the mechanism has been performed, including stereochemical analysis and electronic profiling
在这项工作中,描述了通过路易斯酸催化的供体-受体 (DA) 环丙烷和醛的 [3 + 2] 环加成反应一步非对映选择性合成顺式-2,5-二取代四氢呋喃。提供了关于两个反应伙伴的范围和限制。已经对该机制进行了详细检查,包括两种反应物的立体化学分析和电子分析。实验证据支持一种不寻常的立体特异性紧密离子对机制,其中醛作为亲核试剂,丙二酸作为核离剂。该反应在环丙烷供体位点进行反转,并允许将绝对立体化学信息以高保真度转移到产物中。