Denmark S E, Gomez L
Roger Adams Laboratory, Department of Chemistry, University of Illinois, Urbana, 61801.
Org Lett. 2001 Sep 6;3(18):2907-10. doi: 10.1021/ol016385n.
[reaction: see text]. A new class of tandem [4 + 2]/[3 + 2] cycloadditions of nitroalkenes is described in which both pericyclic processes are intramolecular. Two subclasses of intra [4 + 2]/intra [3 + 2] cycloadditions have been explored in which the dipolarophile is tethered at either C(5) or C(6) of the nitronate. For both families of precursors, the cycloadditions occur in good yield and are found to be highly regio- and stereoselective. This method converts linear polyenes to functionalized polycyclic systems bearing up to six stereogenic centers.
[反应：见正文]。本文描述了一类新型的硝基烯烃串联[4 + 2]/[3 + 2]环加成反应，其中两个周环反应均为分子内反应。已探索了两种分子内[4 + 2]/分子内[3 + 2]环加成反应的亚类，其中亲偶极体连接在硝酮的C(5)或C(6)位。对于这两类前体，环加成反应均以良好的产率发生，并且具有高度的区域选择性和立体选择性。该方法将线性多烯转化为带有多达六个立体ogenic中心的官能化多环体系。
