Catalytic Formal Benzylic C–H Bond Functionalization of 2,5-Dialkylfuran Derivatives with Ferrocenyl Alcohols as Alkylation Reagents
摘要:
The inert benzylic C-H bond of pi-electron-rich heteroaromatic 2,5-dialkylfuran derivatives was conveniently functionalized with ferrocenyl alcohols as alkylation reagents under catalytic acidic conditions at room temperature, which features chemo- and regiospecificity, mild and metallic catalyst free conditions, and environmental benignity.
通过根据LFER方程确定一系列二茂铁基-X-苯基甲基阳离子的电逸度(E f)来量化反应中心α位置二茂铁基对反应中心S N 1的供电子作用: log k = s f(E f + N f)。由于高度稳定的过渡态,E f该值比相应的二苯甲基阳离子的值高约八个单位。二茂铁基消除了二茂铁基苯基甲基衍生物中苯基对正电荷稳定的影响,因此抑制了取代基对苯环的速率影响,导致E f参数的范围狭窄和ρ的绝对值小+常数。在B2PLYP-D3 / may-cc-pVTZ理论水平上的计算表明,二茂铁基苯基甲基阳离子中的正电荷从苯基转移到二茂铁基部分,苯环上的取代基对其稳定性影响很小。
The organocatalytic alkylation of 2-methyl-N-heteroaromatics with alcohols has been achieved via SN1-type C(sp3)–H functionalization, providing a green and efficient synthesis of indole and ferrocene-functionalized N-heteroaromatics in high yields.
通过S N 1型C(sp 3)–H官能化已经实现了2-甲基-N-杂芳族化合物与醇的有机催化烷基化,从而以高收率提供了绿色高效的吲哚和二茂铁官能化的N-杂芳族化合物的合成。
Solvolytic behavior of some ferrocenylphenylmethyl‐4‐methoxypyridinium cations in various solvents
作者:Sandra Jurić
DOI:10.1002/poc.4356
日期:2022.8
electron-donor effect of the ferrocenylgroup, it seems that 4-methoxypyridine is a somewhat better leaving group (stronger nucleofuge) if the substrate is benzhydryl-4-methoxypyridinium salts rather than ferrocenylphenylmethyl-4-methoxypyridinium salts. Given that the electron-withdrawing substituents on the 4-position of the pyridine ring increase the rate of the heterolysis step of solvolysis for benzhydryl and
4-甲氧基吡啶 (4-OMePy) 在纯溶剂和水性溶剂中的核逸度是通过应用线性自由能关系 (LFER) 方程从 S N 1 溶剂分解相对于相应的二茂铁基苯基甲基-4-甲氧基吡啶鎓盐的速率常数得出的, log k (25°C) = s f ( N f + E f )。在极性更强的溶剂中,吡啶鎓离子通过溶剂化在反应物基态比在相应的过渡态和反应性(离核性,N f) 的 4-OMePy 降低增加的溶剂极性。由于二茂铁基团的强电子给体效应,如果底物是二茂铁基-4-甲氧基吡啶鎓盐而不是二茂铁基苯基甲基-4-甲氧基吡啶鎓盐,则似乎 4-甲氧基吡啶是一个更好的离去基团(更强的离核剂)。鉴于吡啶环 4 位上的吸电子取代基增加了二苯甲基和二茂铁苯基甲基吡啶鎓盐的溶剂分解杂解步骤的速率,取代吡啶的N f值按N f (4-ClPy) > N f (Py) > N f (4-MePy) > N f(4-OMePy)
Mössbauer studies on ferrocene complexes X. Steric and polar factors in ferrocenyl ketones and carbenium ions