Issue 8, 2011

A DFT study on the mechanism of gold(iii)-catalyzed synthesis of highly substituted furansvia [3, 3]-sigmatropic rearrangements and/or [1, 2]-acyloxy migration based on propargyl ketones

Abstract

The mechanisms of gold(III)-catalyzed synthesis of highly substituted furansvia [3,3]-sigmatropic rearrangements and/or [1,2]-acyloxy migration based on propargyl ketones have been investigated using density functional theory calculations at BHandHLYP/6-31G(d,p) (SDD for Au) level of theory. Solvent effects on these reactions were explored using calculations that included a polarizable continuum model (PCM) for the solvent (toluene). Two plausible pathways that lead to the formation of Au(III) vinyl carbenoid and an allenyl structure through [3,3]-sigmatropic rearrangements, [1,2]-acyloxy migration viaoxirenium and dioxolenylium were performed. Our calculated results suggested: (1) the major pathway of the cycle causes an initial Rautenstrauch-type [1,2]-migration viaoxirenium to form an Au(III) vinyl carbenoid. Subsequent cycloisomerization of this intermediate then provides the corresponding furan whether for the methyl-substituted propargylic acetates or the phenyl-substituted propargylic acetates; (2) for the methyl-substituted propargylic acetates, the formation of Au(III) vinyl carbenoid structures was the rate-determining step. However, intramolecular nucleophilic attack and subsequent cycloisomerization to give the final product was rate-determining for the phenyl-substituted propargylic acetates. The computational results are consistent with the experimental observations of Gevorgyan, et al. for gold(III)-catalyzed synthesis of highly substituted furans based on propargyl ketones.

Graphical abstract: A DFT study on the mechanism of gold(iii)-catalyzed synthesis of highly substituted furansvia [3, 3]-sigmatropic rearrangements and/or [1, 2]-acyloxy migration based on propargyl ketones

Supplementary files

Article information

Article type
Paper
Submitted
30 Nov 2010
Accepted
25 Jan 2011
First published
28 Feb 2011

Org. Biomol. Chem., 2011,9, 2760-2770

A DFT study on the mechanism of gold(III)-catalyzed synthesis of highly substituted furansvia [3, 3]-sigmatropic rearrangements and/or [1, 2]-acyloxy migration based on propargyl ketones

R. Fang, L. Yang and Y. Wang, Org. Biomol. Chem., 2011, 9, 2760 DOI: 10.1039/C0OB01098G

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