A copper-catalyzed asymmetric Friedel-Crafts hydroxyalkylation of pyrazole-4,5-diones with 5-aminoisoxazoles.

An asymmetric Friedel-Crafts hydroxyalkylation reaction of 5-aminoisoxazoles with pyrazole-4,5-diones was developed under the catalysis of 5% chiral copper complexes. This reaction exhibits functional group tolerance and excellent enantioselectivity. Moreover, the reaction can be scaled up and its mechanism was studied.

Construction of a Chiral ß-Fluoroamine by Asymmetric Mannich Reaction of 2-Fluoroindanone with Pyrazolinone Ketimines.

The asymmetric Mannich reaction of 2-fluoroindanone with ketimine was developed under the catalysis of a kind of chiral copper complex, affording a chiral tetrahedral center containing fluorine. A series of ß-fluoroamine derivatives can be obtained in excellent yields (73-94%) with high diastereoselectivities (>99:1 dr) and enantioselectivities (89-99%). The possible transition state was supported by density functional theory calculation.

Construction of chiral N,O-hemiaminals via a copper-catalyzed enantioselective Michael/N-hemiacetalization cascade reaction.

An efficient Michael/N-hemiacetalization cascade reaction of 5-aminoisoxazoles with ß,γ-unsaturated α-ketoesters was developed under the catalysis of a chiral copper complex. A series of optically pure six-membered ring N,O-hemiaminals were obtained with excellent yields (up to 96% yield) and high enantioselectivities (up to 98% ee). The possible transition state was supported by DFT calculations and thereby the corresponding mechanism was proposed.

Efficient enantioselective synthesis of trisubstituted γ-lactam via the Michael addition reaction of 2,3-dioxopyrrolidine with indole in aqueous media.

An efficient enantioselective Michael addition reaction of 2,3-dioxopyrrolidine with indole in aqueous media was developed by virtue of a chiral copper complex. This reaction features air tolerance, a broad substrate scope and mild reaction conditions. Furthermore, a gram-scale synthesis was conducted to afford the corresponding products with a high yield and excellent enantioselectivity. Moreover, the proposed mechanism was supported by control experiments, XPS investigation and DFT calculations.

Stereoselective Copper-Catalyzed Direct Aldol Reaction of ß, γ-Unsaturated α-Ketoesters with Coumaran-3-Ones.

An efficient direct aldol reaction between coumaran-3-ones and ß, γ-unsaturated α-ketoesters by virtue of a chiral copper complex is developed. A series of coumaran-3-one derivatives containing chiral tertiary alcohol structures are obtained in excellent yields and stereoselectivities.

Multifunctionalization of Unactivated Cyclic Ketones via an Electrochemical Process: Access to Cyclic α-Enaminones.

The multifunctionalization of unactivated cyclic ketones was developed via an electrochemically intermolecular α-amination under metal-free conditions. The reaction can be carried out smoothly with a broad scope of the aromatic amines substrates under mild conditions, affording a variety of α-enaminones with good to excellent yields in one step.

Electrocatalytic Tandem Synthesis of 1,3-Disubstituted Imidazo[1,5- a]quinolines via Sequential Dual Oxidative C(sp3)-H Amination in Aqueous Medium.

An NH4I-mediated tandem electrosynthesis of 1,3-disubstituted imidazo[1,5- a]quinolines was developed from readily available starting materials in aqueous medium, affording a variety of 1,3-disubstituted imidazo[1,5- a]quinolines with good to excellent yields.

Enantioselective Michael Addition of Pyrroles with Nitroalkenes in Aqueous Media Catalyzed by a Water-Soluble Catalyst.

A new water-soluble catalytic system was developed and used in an enantioselective Michael addition of pyrroles with nitroalkenes in water to afford nitroethylpyrrole derivatives with both excellent yields and ee values.

Enantioselective Hetero-Diels-Alder Reaction and the Synthesis of Spiropyrrolidone Derivatives.

An efficient enantioselective hetero-Diels-Alder reaction was developed under catalysis of a chiral copper complex. A variety of spiropyrrolidones, which bear a tetra-substituted carbon stereocenter, can be obtained in good yields with excellent enantioselectivities by virtue of this method. Furthermore, a substrate-dependent reaction pathway was proposed on the basis of the isolated intermediates.

The synthesis of benzimidazoles via a recycled palladium catalysed hydrogen transfer under mild conditions.

An efficient synthesis of benzimidazoles was developed by virtue of a recycled palladium catalyzed hydrogen transfer. The reaction can be carried out smoothly under mild conditions to give rise to a variety of benzimidazoles with good to excellent yields. The palladium catalyst could be recovered easily and reused six times with great catalytic activity.

Copper-Catalyzed Chemoselective and Enantioselective Friedel-Crafts 1,2-Addition of Pyrrole with ß,γ-Unsaturated α-Ketoesters.

A Friedel-Crafts alkylation of pyrrole was developed to afford the ß,γ-unsaturated α-hydroxy esters bearing a quaternary stereogenic center with good enantioselectivities and yields. This protocol represents the first report of 1,2-addition of Friedel-Crafts alkylation of pyrrole to ß,γ-unsaturated α-ketoesters.

Electrocatalytic C-H/N-H Coupling of 2'-Aminoacetophenones for the Synthesis of Isatins.

2'-Aminoacetophenones undergo a C(sp3)-H oxidation followed by intramolecular C-N bond formation by virtue of a simple electrochemical oxidation in the presence of n-Bu4NI, providing various isatins with moderate to good yields. The reaction intermediates were detected, and a radical-based pathway was proposed.

Electrosynthesis of (E)-Vinyl Sulfones Directly from Cinnamic Acids and Sodium Sulfinates via Decarboxylative Sulfono Functionalization.

A variety of (E)-vinyl sulfones were constructed directly from cinnamic acids and sodium sulfinates with high regioselectivity at room temperature by virtue of an electrocatalytic oxidation. A radical intermediate was detected, and the corresponding mechanism was investigated.

Asymmetric Formal Aza-Diels-Alder Reaction of Trifluoromethyl Hemiaminals with Enones Catalyzed by Primary Amines.

A primary amine-catalyzed asymmetric formal aza-Diels-Alder reaction of trifluoromethyl hemiaminals with enones was developed via a chiral gem-diamine intermediate. This novel protocol allowed facile access to structurally diverse trifluoromethyl-substituted piperidine scaffolds with high stereoselectivity. The utility of this method was further demonstrated through a concise approach to biologically active 4-hydroxypiperidine. More importantly, a stepwise mechanism involving an asymmetric induction process was proposed to rationalize the positive correlation between the chirality of the gem-diamine intermediate and the formal aza-Diels-Alder product.

Copper-Catalyzed Enantioselective Hetero-Diels-Alder Reaction of Danishefsky's Diene with Glyoxals.

The highly enantioselective hetero-Diels-Alder reaction of Danishefsky's diene with glyoxals was developed by virtue of a readily accessible chiral copper catalyst. This efficient transformation provided a facile and scalable access to a wide range of biologically active dihydropyrones with a high level of enantioselectivities. Moreover, the substrate scope of this reaction could be extended to isatins with this catalytic system. More importantly, the mechanism involved in this reaction was proposed on the basis of the unambiguous structures of intermediates.

Highly Diastereo- and Enantioselective Michael Addition of Nitroalkanes to 2-Enoyl-Pyridine N-Oxides Catalyzed by Scandium(III)/Copper(II) Complexes.

A C2 -symmetric Schiff-base ligand, derived from tridentate-Schiff-base, was developed and successfully applied to the asymmetric Michael addition of nitroalkanes to 2-enoyl-pyridine N-oxides. With this newly catalytic system, an unprecedented diastereoselectivity was obtained in the asymmetric Michael addition of nitroalkanes to 2-enoyl-pyridine N-oxides. In addition, a switch in enantioselectivity was achieved by using this newly catalytic system and our previous catalyst. After a facile reduction, the optically active adduct was converted to a biologically active dihydro-2H-pyrrol 4 a. Furthermore, a connection of two tridentate-Schiff-base subunits proved to be an effective strategy in ligand design.

Copper-catalyzed radical methylation/C-H amination/oxidation cascade for the synthesis of quinazolinones.

A copper-catalyzed radical methylation/sp(3) C-H amination/oxidation reaction for the facile synthesis of quinazolinone was developed. In this cascade reaction, dicumyl peroxide acts not only as a useful oxidant but also as an efficient methyl source. Notably, a methyl radical, generated from peroxide, was confirmed by electron paramagnetic resonance for the first time.

Enantioselective copper(I/II)-catalyzed conjugate addition of nitro esters to ß,γ-unsaturated α-ketoesters.

A highly enantioselective Michael addition of nitroacetates to ß,γ-unsaturated α-ketoesters was developed by using chiral copper catalysts. The Michael addition products can be obtained in high yields with up to 99 % ee. With these densely functionalized products, the chiral cyclic nitrones, which are important synthetic intermediates, can be obtained in one step.

Electrochemical dual oxidative C(sp3)-H amination: switchable synthesis of imidazo-fused quinazolinones.

An efficient electrochemical dual C(sp3)-H amination was developed under metal-free and chemical oxidant-free conditions. A series of imidazo[1,5-a]quinazolin-5(4H)-ones and 5-oxo-4,5-dihydroimidazo[1,5-a]quinazoline-3-carbonitriles can be obtained in high yields and the product distribution can be modulated by virtue of this method. The reaction mechanism was investigated and the corresponding intermediates were studied. The reaction features a broad substrate scope, regulation of the product distribution, mild conditions and scalable preparation.

Direct electrosynthesis of ketones from benzylic methylenes by electrooxidative C-H activation.

Electrify your chemistry! Direct electrosynthesis of ketones from benzylic methylenes in an undivided cell was realized in moderate to good yields. In this electrosynthesis, electrons instead of conventional oxidants and catalysts are employed to make the reaction environmentally benign. Moreover, the reaction intermediate radical was detected by ESR spectroscopy and the reaction mechanism was clarified.