A significant substituent effect on the regioselectivity in addition of alkynes to 3-substituted pyridines
作者:Shinji Yamada、Aya Toshimitsu、Yasuko Takahashi
DOI:10.1016/j.tet.2009.01.022
日期:2009.3
A substituent at the 3-position on a pyridine ring significantly affects the regioselectivity during the addition of alkynes to pyridinium salts. When the substituent is an electron-withdrawing group, 1,6-adducts are predominantly produced, whereas, 1,2-adducts become the major products when the substituent is an electron-donating group. The changes in the regioselectivity depending on the substituent
吡啶环上3位的取代基会显着影响将炔烃加至吡啶鎓盐中的区域选择性。当取代基为吸电子基团时,主要产生1,6-加合物,而当取代基为给电子基团时,1,2-加合物成为主要产物。取决于取代基的区域选择性的变化可以通过产物稳定性的差异来解释。产生的二氢吡啶很容易与氯腈以定量产率芳香化为二取代的吡啶。