Robust Buchwald–Hartwig amination enabled by ball-milling
作者:Qun Cao、William I. Nicholson、Andrew C. Jones、Duncan L. Browne
DOI:10.1039/c8ob01781f
日期:——
An operationally simple mechanochemical method for the Pd catalysed Buchwald–Hartwig amination of arylhalides with secondary amines has been developed using a Pd PEPPSI catalyst system.
Robust acenaphthoimidazolylidene palladiumcomplexes have been demonstrated as highlyefficient and general catalysts for the sterically hindered Suzuki–Miyaura cross-coupling reactions in excellent yields even with low catalyst loadings under mild reaction conditions. The high catalytic activity of these complexes highlights that, besides the “flexible steric bulky” concept, σ-donor properties of
N‐Heterocyclic Olefin‐Ligated Palladium(II) Complexes as Pre‐Catalysts for Buchwald–Hartwig Aminations
作者:Ian C. Watson、André Schumann、Haoyang Yu、Emma C. Davy、Robert McDonald、Michael J. Ferguson、Christian Hering‐Junghans、Eric Rivard
DOI:10.1002/chem.201901376
日期:2019.7.22
New N‐heterocyclic olefins (NHOs) are described with functionalization on the ligandheterocyclic backbone and terminal alkylidene positions. Various PdII–NHO complexes have been formed and their use as pre‐catalysts in Buchwald–Hartwig aminations was explored. The most active system for catalytic C−N bond formation between hindered arylamine and arylhalide substrates was accessed by combining a backbone
描述了在配体杂环主链和末端亚烷基位置有官能化的新型N-杂环烯烃(NHO)。已经形成了各种Pd II- NHO络合物,并探索了它们在布赫瓦尔德-哈特维希胺化中作为预催化剂的用途。受阻的芳基胺和芳基卤化物底物之间形成催化C-N键的活性最高的系统是通过在NaO t Bu为碱的情况下将主链甲基化的NHO与[Pd(肉桂基)Cl] 2结合而获得的。在这些活性系统中,证据表明催化作用是由胶态钯金属介导的,这突出了与常用的N杂环卡宾配体相比,NHO具有不同的配位能力。
Pyracene-Linked Bis-Imidazolylidene Complexes of Palladium and Some Catalytic Benefits Produced by Bimetallic Catalysts
Two new palladiumcomplexes with a pyracene‐linked bis‐imidazolylidene (pyrabim) group have been obtained and fully characterized. The related monometallic analogues were obtained from the coordination of an acetanaphthene‐supported N‐heterocyclic carbene (NHC). The catalytic properties of all complexes were studied in the acylation of aryl halides with hydrocinnamaldehyde, and in the Suzuki–Miyaura
Mild Negishi Cross-Coupling Reactions Catalyzed by Acenaphthoimidazolylidene Palladium Complexes at Low Catalyst Loadings
作者:Zelong Liu、Ningning Dong、Mizhi Xu、Zheming Sun、Tao Tu
DOI:10.1021/jo400803s
日期:2013.8.2
3a exhibited extremely high catalytic activity toward Negishicross-coupling of alkylzinc reagents with a wide range of (hetero)arylhalides under mild reaction conditions within 30 min. Besides a great number of bromoarenes, various less expensive and inactive (hetero)aryl chlorides were coupled successfully with the alkyl- and arylzincreagents, in which active functional groups (such as -NH2) were
考虑到衍生自π-延伸的咪唑鎓盐的亚烷基的强大的σ-供体性质有利于提高所得钯N-杂环卡宾配合物的催化活性,因此制备了具有健壮的并咪唑-亚烷基钯配合物3a - c,具有不同的大取代基团通过在纯净的3-氯吡啶中与PdCl 2和K 2 CO 3加热,从相应的啶咪唑氯化物中得到满意的收率。即使在催化剂负载量低至0.25 mol%的情况下,配合物3a在温和的反应条件下,在30分钟内显示出对烷基锌试剂与各种(杂)芳基卤化物的Negishi交叉偶联极高的催化活性。除了大量的溴代芳烃外,还成功地将各种较便宜且不活泼的(杂)芳基氯化物与烷基-和芳基锌试剂偶联,其中具有活性官能团(例如-NH 2))即使在无保护的一锅双偶转换中也具有良好的耐受性。此外,在与仲烷基锌试剂偶联的情况下,有效抑制了导致异构化的线性产物的不希望的β-氢化物消除。通过杂芳基锌试剂和杂环氯代芳烃的偶联,该催化剂体系还显示出在杂二芳基结构方面