Sterically Bulky Thioureas as Air- and Moisture-Stable Ligands for Pd-Catalyzed Heck Reactions of Aryl Halides
作者:Dan Yang、Ying-Chun Chen、Nian-Yong Zhu
DOI:10.1021/ol049697+
日期:2004.5.1
We demonstrate that sterically bulky N,N'-disubstituted cyclic thiourea-Pd(0) complexes are air- and moisture-stable and highly active catalysts for palladium-catalyzed Heck reaction of aryl iodides and bromides with olefins (TONs up to 500000 for the reaction of PhI and methyl acrylate). Even activated arylchlorides can undergo complete conversion in Bu(4)NBr in the presence of 1 mol % Pd catalyst
The invention provides N,N′-disubstituted monothiourea or bis-thiourea-Pd(0) complexes that are useful as catalysts for palladium-catalyzed Heck reaction of aryl iodides and bromides with olefins, and as catalysts for palladium catalyzed Suzuki reactions of organoboric compounds and aryl halides.
Straightforward access to chalcogenoureas derived from N-heterocyclic carbenes and their coordination chemistry
作者:Marina Saab、David J. Nelson、Nikolaos V. Tzouras、Tahani A. C. A. Bayrakdar、Steven P. Nolan、Fady Nahra、Kristof Van Hecke
DOI:10.1039/d0dt02558e
日期:——
Chalcogen-based urea compounds supported by a wide range of N-heterocycliccarbenes are synthesised and fully characterised. Coordination of selenoureas is further explored with Group 11 transition metals to form new copper, gold and silver complexes. Single crystal X-ray analyses unambiguously establish the solid-state coordination of these complexes and show that the geometry of a complex is highly influenced
Reactions of <i>N</i>-heterocyclic carbene-based chalcogenoureas with halogens: a diverse range of outcomes
作者:Marina Saab、David J. Nelson、Matthew C. Leech、Kevin Lam、Steven P. Nolan、Fady Nahra、Kristof Van Hecke
DOI:10.1039/d2dt00010e
日期:——
the reactions of chalcogenoureas derivedfrom N-heterocyclic carbenes, referred to here as [E(NHC)], with halogens. Depending on the structure of the chalcogenourea and the identity of the halogen, a diverse range of reactivity was observed and a corresponding range of structures was obtained. Cyclic voltammetry was carried out to characterise the oxidation and reduction potentials of these [E(NHC)]
我们研究了衍生自N-杂环卡宾的硫属元素脲与卤素的反应,此处称为 [E(NHC)]。根据硫属脲的结构和卤素的特性,观察到不同范围的反应性,并获得相应范围的结构。进行循环伏安法以表征这些 [E(NHC)] 物质的氧化和还原电位;发现硒脲比相应的硫脲更容易氧化。在某些情况下,发现这些化合物的氧化电位与相应 NHC 的电子特性之间存在相关性。这些硫属元素脲与不同卤化试剂 (Br 2 , SO 2 Cl 2 ) 的反应性, I 2 ) 进行了研究,并使用 NMR 光谱和单晶 X 射线衍射对产物进行了表征。X 射线分析阐明了所得产物的固态配位类型,表明可以获得多种可能的加合物。在某些情况下,我们能够推断结构/活性相关性来解释观察到的反应性和氧化电位趋势。
Unveiling the redox-active character of imidazolin-2-thiones derived from amino-substituted N-heterocyclic carbenes