Synthesis of<i>gem</i>-Diaurated Species from Alkynols
作者:Alexander Zhdanko、Martin E. Maier
DOI:10.1002/chem.201204491
日期:2013.3.18
A number of enol ether‐derived diaurated species were synthesized directly from different alkynols and cationic gold complexes in the presence of a non‐nucleophilic base (proton sponge). The reaction can be easily applied for in situ generation of diaurated speciesfrom all common types of hydroalkoxylation substrates: 5‐endo, 5‐exo/6‐endo, 6‐exo/7‐endo and intermolecular types. Six examples were also
在非亲核碱(质子海绵)存在的情况下,由不同的炔醇和阳离子金络合物直接合成了许多烯醇醚衍生的弱化物种。该反应可轻松用于从所有常见类型的加氢烷氧基化底物上原位生成加氢物种:5-内,5-外// 6-内,6-外/ 7-内和分子间类型。还以稳定状态的六氟锑酸盐的形式单独合成了六个实例。尽管从所有常规单核金催化剂中都能可靠地获得低价物质,但使用双核金催化剂通常会得到具有不同性质的低价物质。初步结果指出了双核金催化剂行为的复杂性,将来需要对该子类进行更多的研究。还研究了由各种金-氧化合物(LAu)2 OH +,(LAu)3 O +和LAuOH(L =膦配体)形成的弱化物种。在这三种类型中,只有(LAu)2 OH +具有反应性,而(LAu)3 O +LAuOH和LAuOH本身不具有反应性,但需要酸性助催化剂才能进行反应。这些化合物的反应能力差异是由这些化合物生成必要的乙炔π-复杂中间体的能力解释的。
Quantitative Evaluation of the Stability of <i>gem</i>-Diaurated Species in Reactions with Nucleophiles
作者:Alexander Zhdanko、Martin E. Maier
DOI:10.1021/om400083f
日期:2013.3.25
The reactivity of diaurated species toward nucleophiles was investigated. The reaction yields vinyl gold species and is described as simple S(N)2 ligand exchange at gold. Using suitably strong nucleophiles, equilibrium constants were determined to measure the stability of various diaurated species. On the basis of these equilibrium constants the influence of ligand and the nature of vinyl cores on the stability were analyzed. These results have direct implication for gold catalysis: it was demonstrated that vinyl gold intermediates bind the catalytic LAu+ species generally stronger than an alkyne (the substrate) by a factor of 10(6)-10(9). This demonstrates that the formation of diaurated species from vinyl gold intermediates is thermodynamically favored in a catalytic reaction.
The Mechanism of Gold(I)-Catalyzed Hydroalkoxylation of Alkynes: An Extensive Experimental Study
作者:Alexander Zhdanko、Martin E. Maier
DOI:10.1002/chem.201303795
日期:2014.2.10
An extensiveexperimentalstudy of the mechanism of gold(I)‐catalyzed hydroalkoxylation of internal alkynes has been conducted by using NMR spectroscopy. This study was focused on the organogold intermediates, observations of actual catalytic intermediates in situ, and the reaction kinetics that are involved in this reaction. Based on the experimental results, a complete mechanistic picture was established
Visible-light induced eosin Y catalysed C(sp2)-H alkylation of carbonyl substrates via direct HAT
作者:Satya Prakash Singh、Vishal Srivastava、Pravin K. Singh、Praveen P. Singh
DOI:10.1016/j.tet.2023.133245
日期:2023.2
(HAT) catalyst for C–Hactivation. A study that utilized the alkylation of C–H bonds with electron-deficientalkenes as a paradigm provided a very wide substrate scope that made it simple to access a number of significant synthons. This green and sustainable eosin Y-based photocatalytic hydrogen atom transfer method promises to diversify the functionalization of a variety of native C–H bonds.