Charge Delocalization in Persistent Benz[<i>a</i>]anthracenium Cations BAH<sup>+</sup> and Related α-Carbocations/Carboxonium Ions: Modeling Epoxide Ring Opening in Potent Carcinogens
作者:Kenneth K. Laali、Mutsuo Tanaka
DOI:10.1021/jo980722x
日期:1998.10.1
overtime in favor of 3aH(+)() (ipso-attack at bay-region), showing it to be the thermodynamic cation. 3-Methylcholanthrene, 3MC, is exclusively protonated at C-6 (-->4aH(+)()). Cation 5(+)() (a simplified model for bay-region epoxide ring opening) is cleanly formed via its carbinol 5-OH with FSO(3)H/SO(2)ClF. Ketone 6 is O-protonated in TFAH and in TFAH/H(2)SO(4) to give the bay-region carboxonium ion 6H(+)();
母体BA 1在C-7 / C-12处质子化,从而以3:1的比例生成1H(+)()和1aH(+)(),这不受温度和超酸体系变化的影响。通过在C-1(1-MBA)处引入甲基增加海湾区域的空间拥挤,可将C-7 / C-12质子化的氢离子2H(+)()/ 2aH(+)()与10:1。高效的7,12-二甲基苯并[a]蒽7,12-DMBA,产生两种ipso质子化阳离子3aH(+)()/ 3H(+)()的1:1混合物:3:1a超时,有利于3aH(+)()(海湾区域的ipso攻击),表明它是热力学阳离子。3-甲基胆蒽3MC仅在C-6(-> 4aH(+)())上质子化。阳离子5(+)()(海湾区域环氧化物开环的简化模型)是通过其甲醇5-OH与FSO(3)H / SO(2)ClF干净形成的。酮6在TFAH和TFAH / H(2)SO(4)中被O质子化,得到海湾区域的碳鎓离子6H(+)();它在FSO(3)H.SbF(5)(4:1)/