bases were lithium diisopropylamide (LDA), lithium hexamethyldisilazide (LHMDS), and lithium tetramethylpiperidide (LTMP). Isotope effects for attack at methyl, calculated from product ratios, showed a variety of temperature dependences: normal (A aH /A aD =0.6-0.8, all reactions in THF-HMPA) to temperature independent (k H /k D and A aH /A aD =2.8-2.9, LDA in THF) to inverse (A aH /A aD =12.3, LTMP
在
四氢呋喃 (THF) 或 THF-六甲基
磷酰胺 (HMPA)(3 mol/mol 碱)中用各种碱(3 mol/mol 酮)处理 2-pentanone 和 2-pentanone-1,1,1-d 3 ) 得到烯醇化物混合物,用三甲基甲
硅烷基
氯 (TMSCl) 处理得到三甲基甲
硅烷基烯醇醚(80-100% 产率,大部分 >90%),用于 GC 分析。碱是
二异丙基氨基
锂 (
LDA)、六甲基二
硅叠氮化
锂 (L
HMDS) 和
四甲基哌啶锂 (L
TMP)。从产物比率计算的甲基攻击的同位素效应显示出各种温度依赖性:正常(A aH /A aD =0.6-0.8,THF-HMPA 中的所有反应)到温度无关(k H /k D 和 A aH /A aD =2.8-2.9,
LDA in THF) 反转(A aH /A aD =12.3, L
TMP in THF)