skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • Strategies for remote enantiocontrol in chiral gold( iii ) complexes applied to catalytic enantioselective γ,δ-Diels–Alder reactions
Title: Strategies for remote enantiocontrol in chiral gold( iii ) complexes applied to catalytic enantioselective γ,δ-Diels–Alder reactions
The use of chiral square planar gold( iii ) complexes to access enantioenriched products has rarely been applied in asymmetric catalysis. In this context, we report a mechanistic and synthetic investigation into the use of N-heterocyclic (NHC) gold( iii ) complexes in γ,δ-Diels–Alder reactions of 2,4-dienals with cyclopentadiene. The optimal catalyst bearing a unique 2-chloro-1-naphthyl substituent allowed efficient synthesis of functionally rich carbocycles in good yields, diastereo- and enantioselectivities. Transition state and multivariate linear regression (MLR) analysis of both catalyst and substrate trends using molecular descriptors derived from designer parameter acquisition platforms, reveals attractive non-covalent interactions (NCIs) to be key selectivity determinates. These analyses demonstrate that a putative π–π interaction between the substrate proximal double bond and the catalyst aromatic group is an essential feature for high enantioselectivity.  more » « less
Award ID(s):
1763436
PAR ID:
10184605
Author(s) / Creator(s):
; ; ; ; ; ; ;
Date Published:
Journal Name:
Chemical Science
Volume:
11
Issue:
25
ISSN:
2041-6520
Page Range / eLocation ID:
6450 to 6456
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; ; (, Angewandte Chemie International Edition)
    Abstract Stereoselective thioallylation of alkynes under possible gold redox catalysis was accomplished with high efficiency (as low as 0.1 % catalyst loading, up to 99 % yield) and broad substrate scope (various alkynes, inter‐ and intramolecular fashion). The gold(I) catalyst acts as both a π‐acid for alkyne activation and a redox catalyst for AuI/IIIcoupling, whereas the sulfonium cation generated in situ functions as a mild oxidant. This novel methodology provides an exciting system for gold redox catalysis without the need for a strong oxidant. 
    more » « less
  2. ; ; ; (, Chemical Communications)
    null (Ed.)
    Ethylene complexes of gold( i ) have been stabilized by electron-rich, κ 2 -bound tris(pyrazolyl)borate ligands. Large up-field shifts of olefinic carbon NMR resonances and relatively long CC distances of gold bound ethylene are indicative of significant Au( i ) → ethylene π-backbonding relative to the analog supported by a weakly donating ligand, consistent with the computational data. 
    more » « less
  3. ; (, Organic Chemistry Frontiers)
    null (Ed.)
    Macrocyclic hosts have long been used for guest encapsulation, and recently a new application has emerged; employment as supramolecular elements for capture and recovery of gold through host/guest co-precipitation. The guests are square-planar tetrahaloaurate anions, practically important gold complexes with a capacity to engage in non-covalent interactions such as hydrogen bonding and Au–π interactions. The successful macrocyclic hosts for co-precipitation include cyclodextrins, cucurbiturils, and cyclophanes, with recent expansion of the structural scope to include acyclic amides. 
    more » « less
  4. ; ; (, The Journal of Organic Chemistry)
    A thioarylation method is developed for the synthesis of 2,3-dihydrothiopheniums through an electrophilic-cyclization–cross-coupling mechanism, harnessing the gold(I)/(III) cycle of the recently developed MeDalPhosAuCl catalyst. Single-crystal X-ray crystal structural analysis of the dihydrothiophenium products characterized the anti-addition of the sulfur and Csp2 group to the alkyne and a preference for 5-endo dig cyclization. The dihydrothiophenium products are demonstrated as synthetic building blocks for stereodefined acyclic tetrasubstituted alkenes upon ring-opening reaction with amines. Intramolecular competition experiments show the favorability of Csp3 tether cyclizations over Csp2 tethers, preferentially generating dihydrothiopheniums over thiopheniums. Intermolecular competition experiments of alkyne aryl groups and an intermolecular aryl iodide competition suggest a rate-determining reductive elimination step in the gold(I)/gold(III) catalytic cycle. This rate-determining step is further supported by HRMS analysis of reaction intermediates that identify the catalyst resting state under turnover conditions. Catalyst poisoning experiments provide evidence of substrate inhibition, further consistent with these conclusions. 
    more » « less
  5. ; ; (, Chemical Communications)
    A 9,9-dimethylxanthene-based ligand substituted at the 4- and 5-positions by a phosphine and a xanthylium unit, respectively, has been prepared and converted into an AuCl complex, the structure of which reveals an intramolecular Au–Cl⋯π + interaction. This new ligand platform was also found to support the formation of an unprecedented hydroxytrifluoroborate derivative featuring a “hard/soft” mismatched Au– μ (OH)–BF 3 motif. Despite its surprising stability, this gold hydroxytrifluoroborate complex is a remarkably potent carbophilic catalyst which readily activates alkynes, without activator. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email