An official website of the United States government
Abstract Enantioselective, intermolecular alkene arylamination was achieved through gold redox catalysis. Screening of ligands revealed chiral P,N ligands as the optimal choice, giving alkene aminoarylation with good yields (up to 80 %) and excellent stereoselectivity (up to 99 : 1er). As the first example of enantioselective gold redox catalysis, this work confirmed the feasibility of applying a chiral ligand at the gold(I) stage, with the stereodetermining step (SDS) at the gold(III) intermediate, thus opening up a new way to conduct gold redox catalysis with stereochemistry control.
more »
« less
Asymmetric Hydrative Aldol Reaction (HAR) via Vinyl‐Gold Promoted Intermolecular Ynamide Addition to Aldehydes
Abstract Herein, we reported an intermolecular asymmetric hydrative aldol reaction through vinyl‐gold intermediate under ambient conditions. This tandem alkyne hydration and sequential nucleophilic addition afforded a “base‐free” approach to β‐hydroxy amides with high efficiency (up to 95 % yields, >50 examples). Vinyl gold intermediate was applied as reactive nucleophile and Fe(acac)3was used as the critical co‐catalyst to prevent undesired protodeauration, allowing this transformation to proceed under mild conditions with good functional group tolerance and excellent stereoselectivity (>20 : 1 d.r. and up to 99 % ee).
more »
« less
- Award ID(s):
- 1665122
- PAR ID:
- 10425331
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie International Edition
- Volume:
- 62
- Issue:
- 31
- ISSN:
- 1433-7851
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Stereoselective Zweifel olefination using boronate complexes carrying two different reactive π‐systems was achieved to synthesize vinyl heteroarenes and conjugated 1,3‐dienes in good yield and up to 100 % stereoselectivity, which remains unexplored until now. Most importantly, we report the unprecedented formation ofEvs.Z‐vinyl heteroarenes for different heteroarenes under identical conditions. Density functional theory (DFT) investigations unveil the mechanistic dichotomy between olefin and heteroarene activation followed by 1,2‐migration, leading toEorZ‐vinyl heteroarenes respectively. We also report a previously unknown reversal of stereoselectivity by using 2,3‐Dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ) as an electrophile. The Zweifel olefination using a boronate complex that carries two different olefins was previously unexplored due to significant challenges associated with the site‐selective activation of olefins. We have solved this problem and reported the site‐selective activation of olefins for the stereoselective synthesis of 1,3‐dienes.more » « less
-
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
-
Abstract 1T-MoS2and single-atom modified analogues represent a highly promising class of low-cost catalysts for hydrogen evolution reaction (HER). However, the role of single atoms, either as active species or promoters, remains vague despite its essentiality toward more efficient HER. In this work, we report the unambiguous identification of Ni single atom as key active sites in the basal plane of 1T-MoS2(Ni@1T-MoS2) that result in efficient HER performance. The intermediate structure of this Ni active site under catalytic conditions was captured by in situ X-ray absorption spectroscopy, where a reversible metallic Ni species (Ni0) is observed in alkaline conditions whereas Ni remains in its local structure under acidic conditions. These insights provide crucial mechanistic understanding of Ni@1T-MoS2HER electrocatalysts and suggest that the understanding gained from such in situ studies is necessary toward the development of highly efficient single-atom decorated 1T-MoS2electrocatalysts.more » « less
