Face Selectivity of theDiels-Alder Additions of Sulfur-Substituted Dienes and Tetraenes Grafted onto 7-Oxabicyclo[2.2.1]heptanes
作者:Jean-Marc Tornare、Pierre Vogel、A. Alan Pinkerton、Dieter Schwarzenbach
DOI:10.1002/hlca.19850680815
日期:1985.12.18
on the nature of the dienophile. It is exo-face selective with bulky dienophiles such as ethylene-tetracarbonitrile (TCNE) and 2-nitro-1-butene and endo-face selective with methyl vinyl ketone, methyl acrylate, and 3-butyn-2-one. In the presence of a Lewis acid, the face selectivity of the Diels-Alder reaction can be reversed. The addition of the first equivalent of a dienophile to tetraene 17 is at
立体选择性合成2-亚甲基-3-[(Z)-(2-硝基苯基亚硫基)亚甲基] -7-氧杂双环[2.2.1]-庚烷(16),1,4-环氧-1,2,3,4-四氢-5,8-二甲氧基-2-亚甲基-3-[(Z)-(2-硝基苯基亚硫基)亚甲基]蒽(18)和1,4-环氧-1,2,3,4-四氢-5,提出了8-二甲氧基-2-亚甲基-3-[(Z)-(苯基亚磺酰基)-亚甲基]蒽(19)。这些S-取代的二烯和2,5-二甲叉基-3,6-双[(Z)-(2-硝基苯基)亚硫基]亚甲基} -7-氧杂双环[2.2.1]庚烷的Diels - Alder加成反应(17)被发现是有选择性的和“邻位”区域特异性的。脸部选择性取决于亲二烯体的性质。它是外切-面选择性的亲二烯体笨重,如乙烯- tetracarbonitrile(TCNE)和2-硝基-1-丁烯和内面取向选择性与甲基乙烯基酮,丙烯酸甲酯,和3-丁炔-2-酮。在路易斯酸的存在下,Diels