合成了含有吡啶基和羟基官能化的N-杂环卡宾(NHC)的Ni II配合物1,并评估了其在无碱条件下选择性腈水合为相应酰胺的催化作用。标题化合物利用半不稳定的吡啶基单元通过氢键与催化相关的水分子相互作用,并促进对腈的亲核水攻击。各种各样的腈被水合成相应的酰胺,包括药物鲁芬酰胺,利福特和吡乙酰胺。在中性条件下,可从氰醇获得具有合成挑战性的α-羟酰胺。缺少吡啶基单元的相关催化剂(即化合物2和4)没有活性,而同时含有吡啶基和羟基或仅含有吡啶基侧基的那些(即化合物1和3)显示出实质性的活性。在不同的结晶条件下分离了键合异构体1',其中羟基与金属结合而不是吡啶基,这表明配体具有半不稳定的行为。额外的p K a测量值揭示了在催化条件下可及的吡啶基单元。动力学研究支持将配体促进的亲核水添加到与金属结合的腈基上。这项工作报告了一种镍基催化剂,在水合化学中具有功能半合性。
Bifunctional Water Activation for Catalytic Hydration of Organonitriles
作者:Prosenjit Daw、Arup Sinha、S. M. Wahidur Rahaman、Shrabani Dinda、Jitendra K. Bera
DOI:10.1021/om300297y
日期:2012.5.14
Treatment of [Rh(COD)(mu-Cl)](2) with excess (BuOK)-Bu-t and subsequent addition of 2 equiv of PIN center dot HBr in THF afforded [Rh(COD)(kappa C-2-PIN)Br] (1) (PIN = 1-isopropyl-3-(5,7-dimethyl-1,8-naphthyrid-2-yl)imidazol-2-ylidene, COD = 1,5-cyclooctadiene). The X-ray structure of 1 confirms ligand coordination to "Rh(COD)Br" through the carbene carbon featuring an unbound naphthyridine. Compound 1 is shown to be an excellent catalyst for the hydration of a wide variety of organonitriles at ambient temperature, providing the corresponding organoamides. In general, smaller substrates gave higher yields compared with sterically bulky nitriles. A turnover frequency of 20 000 h(-1) was achieved for the acrylonitrile. A similar Rh(I) catalyst without the naphthyridine appendage turned out to be inactive. DFT studies are undertaken to gain insight on the hydration mechanism. A 1:1 catalyst-water adduct was identified, which indicates that the naphthyridine group steers the catalytically relevant water molecule to the active metal site via double hydrogen-bonding interactions, providing significant entropic advantage to the hydration process. The calculated transition state (TS) reveals multicomponent cooperativity involving proton movement from the water to the naphthyridine nitrogen and a complementary interaction between the hydroxide and the nitrile carbon. Bifunctional water activation and cooperative proton migration are recognized as the key steps in the catalytic cycle.
An Organic Molecule Modulated Chemoselective Cyclization of Alkynyl Nitriles Tethered to 2-Alkyl Substituted Chromones with Multireactive Sites
作者:Liping Huang、Yang Liu、Fuchun Xie、Youhong Hu
DOI:10.1021/ol302964x
日期:2012.12.21
A small organic molecule phenylacetonitrile promoted chemoselective cyclization of (chromen-3-yl)alkynylnitriles to generate a novel tetracyclic or tricyclic chromone scaffold has been discovered. Importantly, the phenylacetonitrile serves as an anion transfer reagent changing the normal reaction of the substrate.
Berther, Chemische Berichte, 1959, vol. 92, p. 2616,2619
作者:Berther
DOI:——
日期:——
OXFORD, ALEXANDER WILLIAM;COATES, IAN HAROL;WEBB, COLIN FREDERICK;BAYS, D+
作者:OXFORD, ALEXANDER WILLIAM、COATES, IAN HAROL、WEBB, COLIN FREDERICK、BAYS, D+
DOI:——
日期:——
Hemilability-Driven Water Activation: A Ni<sup>II</sup>Catalyst for Base-Free Hydration of Nitriles to Amides
作者:Kuldeep Singh、Abir Sarbajna、Indranil Dutta、Pragati Pandey、Jitendra K. Bera
DOI:10.1002/chem.201700816
日期:2017.6.7
The NiII complex 1 containing pyridyl‐ and hydroxy‐functionalizedN‐heterocycliccarbenes (NHCs) is synthesized and its catalytic utility for the selective nitrile hydration to the corresponding amide under base‐free conditions is evaluated. The title compound exploits a hemilabile pyridyl unit to interact with a catalytically relevant water molecule through hydrogen‐bonding and promotes a nucleophilic
合成了含有吡啶基和羟基官能化的N-杂环卡宾(NHC)的Ni II配合物1,并评估了其在无碱条件下选择性腈水合为相应酰胺的催化作用。标题化合物利用半不稳定的吡啶基单元通过氢键与催化相关的水分子相互作用,并促进对腈的亲核水攻击。各种各样的腈被水合成相应的酰胺,包括药物鲁芬酰胺,利福特和吡乙酰胺。在中性条件下,可从氰醇获得具有合成挑战性的α-羟酰胺。缺少吡啶基单元的相关催化剂(即化合物2和4)没有活性,而同时含有吡啶基和羟基或仅含有吡啶基侧基的那些(即化合物1和3)显示出实质性的活性。在不同的结晶条件下分离了键合异构体1',其中羟基与金属结合而不是吡啶基,这表明配体具有半不稳定的行为。额外的p K a测量值揭示了在催化条件下可及的吡啶基单元。动力学研究支持将配体促进的亲核水添加到与金属结合的腈基上。这项工作报告了一种镍基催化剂,在水合化学中具有功能半合性。