[4+2] Cycloaddition reactions of 4-sulfur-substituted 2-pyridones with electron-deficient dienophiles
作者:Shang-Shing P. Chou、Hui-Chen Wang、Pong-Won Chen、Chun-Han Yang
DOI:10.1016/j.tet.2008.03.030
日期:2008.5
(dimethyl acetylenedicarboxylate, methyl vinyl ketone, ethyl vinyl ether, and methyl methacrylate) were found not to react with 6a or 6b, but led to the formation of tosyl migration products 4-(phenylthio)-O-tosyl-pyridinol (16a) and 4-(phenylsulfonyl)-O-tosyl-2-pyridinol (16b), respectively. The reactivity, regioselectivity, and stereoselectivity of the cycloaddition reactions were also compared with semi-empirical
[4 + 2]的4-(苯硫基)环加成反应-1-甲苯磺酰基-2-吡啶酮(6A)和4-(苯基磺酰基)-1-甲苯磺酰基-2-吡啶酮(6B)与缺电子亲双烯体7(ñ -甲基马来酰亚胺,ñ苯基马来和丙烯酸甲酯),得到新产品isoquinuclidine 8 - 10。该Ñ甲苯磺酰基团的图6a和6b中也被有效地转化成ñ -烷基衍生物6C - ˚F,这表明朝向与亲双烯体的反应不同的立体选择性7。其他几个亲二烯体15(乙炔二甲酸二甲酯,甲基乙烯基酮,乙基乙烯基醚和甲基丙烯酸甲酯)未与6a或6b反应,但导致形成甲苯磺酰基迁移产物4-(苯硫基)-O-甲苯磺酰基-吡啶醇(16a)和4-(苯磺酰基)-O-甲苯磺酰基-2-吡啶醇(16b)。还与半经验计算比较了环加成反应的反应性,区域选择性和立体选择性。