通过铱催化肟醚和杂芳烃的直接融合,可实现菲啶衍生物的简明合成,这是多环杂芳族合成的级联C–H / C–H交叉偶联/环化策略的成功实例。通过微调反应条件,在相似但不同的条件下,苯并五元杂芳基和简单的五元杂芳基都是合适的底物。关键是正确选择银盐。详细的机理研究表明,第一步C–H / C–H交叉偶联步骤涉及[Ir II ] – [Ir IV ]催化循环,需要Ag 2 O作为氧化剂。对于第二个环化步骤,自由基过程控制了苯并杂芳烃和Ag 2的反应O是必需的;然而,在涉及[Ir I ]-[Ir III ]催化循环的简单五元杂芳烃的反应中,C–H环化作用是必要的,而AgTFA是必需的。
O-Methyl oximes have been employed as nucleophiles in reactions with ketenimines derived from sulfonylazides and terminal alkynes to form N-alkylidene N′-tosylacetimidamide derivatives. The optimized conditions involved the use of CuPF6 and i-Pr2NEt in MeCN at 65 °C. Both O-methyl aldoximes and ketoximes were tolerated under the optimum conditions.
A [Cp*RhIII]‐catalyzed direct C−H amidation is carried out in ionic liquid. Both C(sp2)−H bonds of (hetero)arenes and alkenes and unactivated C(sp3)−H bonds can be easily amidated with high functional‐group tolerance and excellent yields under these conditions. Notably, using [Cp*RhIII]/[BMIM]BF4 (BMIM=1‐butyl‐3‐methylimidazolium) as the green and recyclable medium is environmentally benign, in light
[Cp * Rh III ]催化的直接CHH酰胺化反应在离子液体中进行。在这些条件下,(杂)芳烃和烯烃的C(sp 2)-H键和未活化的C(sp 3)-H键都容易被酰胺化,具有很高的官能团耐受性和优异的收率。值得注意的是,考虑到诸如昂贵的铑催化剂的可重复使用性等特性,使用[Cp * Rh III ] / [BMIM] BF 4(BMIM = 1-丁基-3-甲基咪唑鎓)作为绿色且可回收的介质对环境无害。避免剧毒的有机溶剂,温和的反应条件以及较短的反应时间。
ortho-Olefination of Arylaldehyde O-Methyloximes through Palladium-Catalyzed C-H Activation
作者:Zhipeng Xu、Biao Xiang、Peipei Sun
DOI:10.1002/ejoc.201200393
日期:2012.6
Palladium(II)-catalyzed ortho-olefination of arylaldehydeO-methyloximes by using O-methyloxime as a directing group gave 2-alkenylarylaldehyde O-methyloximes in moderate to good yields. After various reaction parameters (catalyst, oxidant, solvent, and reaction temperature) were examined, the optimal conditions for the reaction were identified. 2-Alkenylarylaldehydes could be obtained conveniently
通过使用 O-甲基肟作为导向基团,钯 (II) 催化芳基醛 O-甲基肟的邻-烯烃化反应以中等至良好的产率得到 2-烯基芳基醛 O-甲基肟。在检查了各种反应参数(催化剂、氧化剂、溶剂和反应温度)后,确定了反应的最佳条件。2-烯基芳醛可以通过偶联产物的水解方便地获得。提供了 C-H 键活化的动力学同位素效应 (kH/kD),并提出了反应的可能机制。
Pd-Catalyzed Multiple CH Functionalization to Construct Biologically Active Compounds from Aryl Aldoxime Ethers with Arenes
作者:Vedhagiri S. Thirunavukkarasu、Chien-Hong Cheng
DOI:10.1002/chem.201102996
日期:2011.12.23
Functional fluorenones: Aromatic aldoximeethers react with unactivated arenes catalyzed by palladium complexes to give biologicallyactive fluoren‐9‐ones (see scheme). MultipleCH bond activation and an oxidative cyclization are involved in the reaction.