Electron-Withdrawing β-Substituent, Ring-Strain, and Ortho Effects on Reactivity, Selectivity, and Stability of <i>o</i>-Alkoxybenzyl Carbocations
作者:Meng-Yun Tseng、Hsin-Yi Hung、Kuangsen Sung
DOI:10.1021/acs.jpca.5b02234
日期:2015.4.30
o-Alkoxybenzyl carbocations 1 and 2 were generated by laser flash photolysis of the corresponding o-alkoxybenzyl alcohols 3 and 4 to understand how the electron-withdrawing β-substituent, the ring-strain, and the ortho effects affect the reactivity (electrophilicity), selectivity, and stability of 1 and 2, and to fit the electrophilicity of 1 and 2 into the current carbocation electrophilicity scale (E)
通过激光闪光光解相应的o-烷氧基苄醇3和4生成o-烷氧基苄基碳阳离子1和2,以了解吸电子的β-取代基,环应变和邻位效应如何影响反应性(亲电性),选择性和稳定性1和2,并以适合的亲电性1和2到当前碳阳离子电性规模(é)。我们的发现是吸电子β取代基和环应变效应使1的稳定性低于2的稳定性3.0 kcal / mol。这些效应加上2的邻位效应使1的活性比2的强,但是1和2对胺亲核试剂的选择性在实验误差范围内几乎相同。1和2的亲电性已很好地适合当前的碳正离子亲电性标度(E)。