Merging Organocatalysis and Gold Catalysis-A Critical Evaluation of the Underlying Concepts

One-Pot Asymmetric Nitro-Mannich/Hydroamination Cascades for the Synthesis of Pyrrolidine Derivatives: Combining Organocatalysis and Gold Catalysis

The highly enantioselective preparation of trisubstituted pyrrolidine derivatives employing a one-pot nitro-Mannich/hydroamination cascade is reported. This cascade approach utilizes an asymmetric bifunctional organocatalytic nitro-Mannich reaction followed by a gold-catalyzed allene hydroamination reaction. The products are afforded in good yields and excellent diastereo- and enantioselectivities.

When gold meets chiral Brønsted acid catalysts: extending the boundaries of enantioselective gold catalysis

This review describes the development in the use of Au(i)/Brønsted acid binary catalytic systems to enable an enantioselective transformation in one-pot that cannot be achieved by gold catalysts alone.

One-pot synthesis of polysubstituted 3-acylpyrroles by cooperative catalysis

Polysubstituted 3-acylpyrroles were synthesized from readily available unsaturated ketones and N-substituted propargylated amines via an aza-Michael/alkyne carbocyclization cascade followed by oxidation in one pot.

Highly enantioselective oxidative tandem cyclization reaction: a chiral ligand and an anion cooperatively control stereoselectivity

The unprecedented combination of a palladium(ii) complex with a chiral Bu-QUOX ligand and a chiral phosphoric acid enables the highly efficient asymmetric oxidative tandem cyclization reaction, providing a straightforward method to access chiral 6,5-bicyclic aza-heterocycles in moderate to good yields and with excellent enantioselectivities.

Gold and BINOL-phosphoric acid catalyzed enantioselective hydroamination/N-sulfonyliminium cyclization cascade

A highly enantioselective hydroamination/N-sulfonyliminium cyclization cascade is reported using a combination of gold(I) and chiral phosphoric acid catalysts. An initial 5-exo-dig hydroamination and a subsequent phosphoric acid catalyzed cyclization process provide access to complex sulfonamide scaffolds in excellent yield and high enantiocontrol. The method can be extended to lactam derivatives, with excellent yields and enantiomeric excesses of up to 93% ee.

Mechanistic investigations into the enantioselective Conia-ene reaction catalyzed by cinchona-derived amino urea pre-catalysts and Cu(I)

The enantioselective Conia-ene cyclization of alkyne-tethered β-ketoesters is efficiently catalyzed by the combination of cinchona-derived amino-urea pre-catalysts and copper(I) salts. The reaction scope is broad and a series of substrates can be efficiently cyclized with high yields and enantioselectivities. Herein, we present a detailed mechanistic study based on experimental considerations and quantum mechanical calculations. Several variables, such as the nature of the organic pre-catalyst and the metal-ion source, have been thoroughly investigated. Kinetic studies, as well as kinetic isotope effects and deuterium labeling experiments have been used to gain further insights into the mechanism and prove the cooperative nature of the catalytic system. Our studies suggest that the rate-limiting step for the reaction involves the β-ketoester deprotonation and that the active species responsible for the enantiodeterming step is monomeric in amino-urea pre-catalyst. Computational studies provide a quantitative understanding of the observed stereoinduction and identify hydrogen bonding from the urea group as a crucial factor in determining the observed enantioselectivity.

Combining oxidative N-heterocyclic carbene catalysis with click chemistry: a facile one-pot approach to 1,2,3-triazole derivatives

A combination of the oxidative N-heterocyclic carbene catalysis and click chemistry has been explored for the direct, one-pot synthesis of 1,2,3-triazole derivatives from aromatic aldehydes. This procedure was found to be very efficient and a variety of 1,2,3-triazole derivatives could be accessed through their corresponding propargyl esters in moderate-to-good yields under mild conditions.

One-pot catalytic enantioselective synthesis of tetrahydropyridines via a nitro-Mannich/hydroamination cascade

The highly enantioselective preparation of synthetically useful tetrahydropyridine derivatives employing a one-pot nitro-Mannich/hydroamination cascade is reported. This approach utilizes an asymmetric organocatalytic nitro-Mannich reaction followed by a gold-catalyzed alkyne hydroamination/isomerization sequence that yields the desired tetrahydropyridines in good yields and high diastereo- and enantioselectivities.