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Mechanistic elucidation of gold(I)-catalyzed oxidation of a propargylic alcohol by a N-oxide in the presence of an imine using DFT calculations

Citation

Zarkoob, F and Ariafard, A, Mechanistic elucidation of gold(I)-catalyzed oxidation of a propargylic alcohol by a N-oxide in the presence of an imine using DFT calculations, Organometallics, 38, (2) pp. 489-497. ISSN 0276-7333 (2019) [Refereed Article]

Copyright Statement

2018 American Chemical Society

DOI: doi:10.1021/acs.organomet.8b00808

Abstract

Density functional theory (DFT) calculations were utilized to investigate the mechanism of the oxidation of an indolyl propargylic alcohol by a N-oxide in the presence of an imine and a gold(I) catalyst. The catalytic reaction is proposed to start from regioselective oxidation of the gold(I)-activated alkyne dictated by a hydrogen bond interaction between the OH group of the propargylic alcohol and the N-oxide. This oxidation was expected to give an α-carbonyl gold carbene complex. In contrast to this expectation, our calculations showed that the corresponding carbene is not a local minimum and the complex undergoes a very fast 1,2 aryl shift to form an alkene complex. Subsequently, an imine is added to the ensuing alkene complex to give an iminium cation from which a cycloaddition process occurs and an indolium is formed. Finally, an N-oxide deprotonates the indolium complex and affords an intermediate which is significantly reactive toward water elimination. Our calculations indicate that the 1,2-aryl shift in α-carbonyl gold carbene complexes is decelerated if the aryl is substituted by an electron-withdrawing group. At the end, we investigated the stability of different gold carbene complexes and found that the identity of the carbene is the determinant of how these carbenes are trapped.

Item Details

Item Type:Refereed Article
Keywords:density functional theory, activation energy, propargylic alcohol
Research Division:Chemical Sciences
Research Group:Organic Chemistry
Research Field:Physical Organic Chemistry
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Chemical Sciences
UTAS Author:Ariafard, A (Associate Professor Alireza Ariafard)
ID Code:134448
Year Published:2019
Funding Support:Australian Research Council (DP180100904)
Web of Science® Times Cited:2
Deposited By:Chemistry
Deposited On:2019-08-13
Last Modified:2019-09-06
Downloads:0

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