Monoaurated vs. diaurated intermediates: causality or independence?†
| Autor: | Jana Roithová, Mariarosa Anania, Juraj Jašík, Elena Shcherbachenko, Jan Zelenka, Lucie Jašíková |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
chemistry.chemical_classification
Reaction mechanism Ketone 010405 organic chemistry Chemistry Kinetics Photodissociation Protonation General Chemistry 010402 general chemistry Photochemistry 01 natural sciences 3. Good health 0104 chemical sciences Catalysis Reaction rate Kinetic isotope effect Spectroscopy and Catalysis |
| Zdroj: | Chemical Science Chemical Science, 11, 4, pp. 980-988 Chemical Science, 11, 980-988 |
| ISSN: | 2041-6539 2041-6520 |
| Popis: | Diaurated intermediates of gold-catalysed reactions have been a long-standing subject of debate. Although diaurated complexes were regarded as a drain of active monoaurated intermediates in catalytic cycles, they were also identified as the products of gold–gold cooperation in dual–activation reactions. This study shows investigation of intermediates in water addition to alkynes catalysed by [(IPr)Au(CH3CN)(BF4)]. Electrospray ionisation mass spectrometry (ESI-MS) allowed us to detect both monoaurated and diaurated complexes in this reaction. Infrared photodissociation spectra of the trapped complexes show that the structure of the intermediates corresponds to α-gold ketone intermediates protonated or aurated at the oxygen atom. Delayed reactant labelling experiments provided the half life of the intermediates in reaction of 1-phenylpropyne (∼7 min) and the kinetic isotope effects for hydrogen introduction to the carbon atom (KIE ∼ 4–6) and for the protodeauration (KIE ∼ 2). The results suggest that the ESI-MS detected monoaurated and diaurated complexes report on species with a very similar or the same kinetics in solution. Kinetic analysis of the overall reaction showed that the reaction rate is first-order dependent on the concentration of the gold catalyst. Finally, all results are consistent with the reaction mechanism proceeding via monoaurated neutral α-gold ketone intermediates only. Reaction kinetics and detected α-gold ketone intermediates reveal that gold-mediated hydration of alkynes does not rely on dual activation. |
| Databáze: | OpenAIRE |
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