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Acyl migration versus epoxidation in gold catalysis: facile, switchable, and atom-economic synthesis of acylindoles and quinoline derivatives

Citation

Tian, X and Song, L and Farshadfar, K and Rudolph, M and Rominger, F and Oeser, T and Ariafard, A and Hashmi, ASK, Acyl migration versus epoxidation in gold catalysis: facile, switchable, and atom-economic synthesis of acylindoles and quinoline derivatives, Angewandte Chemie, 59, (1) pp. 471-478. ISSN 0044-8249 (2020) [Refereed Article]


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Copyright 2020 the authors. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) https://creativecommons.org/licenses/by-nc-nd/4.0/

DOI: doi:10.1002/anie.201912334

Abstract

We report a switchable synthesis of acylindoles and quinoline derivatives via gold‐catalyzed annulations of anthranils and ynamides. α‐Imino gold carbenes, generated in situ from anthranils and an N,O‐coordinated gold(III) catalyst, undergo electrophilic attack to the aryl π‐bond, followed by unexpected and highly selective 1,4‐ or 1,3‐acyl migrations to form 6‐acylindoles or 5‐acylindoles. With the (2‐biphenyl)di‐tert‐butylphosphine (JohnPhos) ligand, gold(I) carbenes experienced carbene/carbonyl additions to deliver quinoline oxides. Some of these epoxides are valuable substrates for the preparation of 3‐hydroxylquinolines, quinolin‐3(4H)‐ones, and polycyclic compounds via facile in situ rearrangements. The reaction can be efficiently conducted on a gram scale and the obtained products are valuable substrates for preparing other potentially useful compounds. A computational study explained the unexpected selectivities and the dependency of the reaction pathway on the oxidation state and ligands of gold. With gold(III) the barrier for the formation of the strained oxirane ring is too high; whereas with gold(I) this transition state becomes accessible. Furthermore, energetic barriers to migration of the substituents on the intermediate sigma‐complexes support the observed substitution pattern in the final product.

Item Details

Item Type:Refereed Article
Keywords:gold catalysis, mechanistic study, acyl migration, epoxidation, Density Functional Theory
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:137655
Year Published:2020
Funding Support:Australian Research Council (DP180100904)
Web of Science® Times Cited:50
Deposited By:Chemistry
Deposited On:2020-02-25
Last Modified:2021-01-27
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