Interestingly, clean dideprotonation was noted from 3-fluoropyridine (at C2 and C4) and 2,6-difluoropyridine (at C3 and C5). The obtained regioselectivities have been discussed in light of the CH acidities of the substrates, determined both in the gas phase (DFT B3LYP and G3MP2B3 levels) and in THF solution. In the case of methoxypyridines, the pKa values have also been calculated for complexes with
室温下,通过使用从ZnCl 2 ·TME
DA(TME
DA = N,N,N ',N'-
四甲基乙二胺)和Li
TMP(
TMP)获得的混合的
锂锌混合物,在
四氢呋喃中对一系列甲氧基和
氟吡啶进行了脱
金属化处理。=
2,2,6,6-四甲基哌啶子酮)的比例为1:3,
金属化的物质被
碘拦截。从4-甲氧基,2-甲氧基,2-甲氧基,2,6-二甲氧基,2-
氟和2,6-二
氟吡啶观察到在3位的有效官能化,并且从3-甲氧基和2,3-二甲氧基
吡啶观察到在4位的高效官能化。有趣的是,注意到3-
氟吡啶(在C2和C4处)和2,6-二
氟吡啶(在C3和C5处)有干净的双质子化。 根据底物的CH酸(在气相(DFT B3LYP和G3MP2B3含量)和THF溶液中测定)的CH酸性,已经讨论了所获得的区域选择性。在甲氧基
吡啶的情况下,还计算了与LiCl和Li
TMP的配合物的p K a值。