Selective and controllable amination and defluoroamidation of α-trifluoromethylstyrene.

We present a blueprint for the amination and defluoroamidation of α-trifluoromethylstyrene. This practical protocol presents a general method for the diversity-oriented synthesis of vicinal trifluoromethyl amines and -difluoro alkenes from α-trifluoromethylstyrene maintaining excellent chemoselectivity. The synthetic strategy features outstanding atom economy and wide functional group tolerance under mild reaction conditions.

Suzuki-Miyaura Type Regioselective C-H Arylation of Aromatic Aldehydes by a Transient Directing Strategy.

Herein, we disclose a common approach for palladium-catalyzed direct coupling of the -C-H bond of aromatic aldehydes with various organoboronic reagents by a transient directing strategy. In contrast to widely used cross-coupling reactions of C-H bonds with aryl halides, which generally need silver salt as a halide removal reagent, the method which used BQ/TFA as weak oxidation system for the Pd/Pd redox cycle is cost-effective, ecofriendly, and more aligned with green catalysis. This broadly applicable method opens up a new and efficient Suzuki-Miyaura coupling route for the direct formation of carbon-carbon bonds by C-H bond activation.

Copper-Catalyzed Transamidation of Unactivated Secondary Amides via C-H and C-N Bond Simultaneous Activations.

Here, we demonstrate that α-C-H and C-N bonds of unactivated secondary amides can be activated simultaneously by the copper catalyst to synthesize α-ketoamides or α-ketoesters in one step, which is a challenging and underdeveloped transformation. Using copper as a catalyst and air as an oxidant, the reaction is compatible with a broad range of acetoamides, amines, and alcohols. The preliminary mechanism studies and density functional theory calculation indicated that the reaction process may undergo first radical α-oxygenation and then transamidation with the help of the resonant six-membered N,O-chelation and molecular oxygen plays a role as an initiator to trigger the transamidation process.

Supported Palladium Nanoparticles Catalyzed Intermolecular Carbopalladation of Nitriles and Organoboron Compounds.

The first heterogeneous catalyzed example for the direct synthesis of aromatic ketones via intermolecular carbopalladation of aliphatic nitriles and organoboron compounds was developed. This mild method proceeds with a supported palladium nanoparticles catalyst that could be reused and recycled five times. The fresh and used catalysts were characterized by XPS and TEM.

Mesoporous Carbon-Supported Pd Nanoparticles in the Metallic State-Catalyzed Acylation of Amides with Aryl Esters via C-O Activation.

Carbon, an abundant, inexpensive, and nonmetallic material, is an inimitable support in heterogeneous catalysis, and variable carbonaceous materials have been utilized to support metal nanoparticle catalysts. We developed an efficient and stable heterogeneous catalyst with highly dispersed metallic palladium nanoparticles embedded in an ordered pore channel of mesoporous carbon and first applied the catalyst to construct imides from amides using aryl esters as an acylation reagent via C-O activation. The catalyst represents excellent catalytic performance and could be reused and recycled five times without any significant decrease in activity.

Regiodivergent CDC reactions of aromatic aldehydes with unactivated arenes controlled by transient directing strategy.

The regiodivergent catalytic dehydrogenative cross-coupling reactions at both sp and sp hybridized carbons of aromatic compounds are particularly challenging. Herein, we report the finding of transient directing group controlled regiodivergent C(sp)-C(sp) and C(sp)-C(sp) cross-coupling in the -methyl benzaldehyde frameworks. Catalyzed by palladium, using KSO or [F] reagents as by-standing oxidants and unactivated arenes as substrates/solvents, various benzyl benzaldehydes or phenyl benzaldehydes were prepared.

[3 + 2 + 1] Pyridine Skeleton Synthesis Using Acetonitrile as C4N1 Units and Solvent.

The first [3 + 2 + 1] methodology for pyridine skeleton synthesis via cascade carbopalladation/cyclization of acetonitrile, arylboronic acids, and aldehydes was developed. This reaction proceeds via six step tandem reaction sequences involving the carbopalladation reaction of acetonitrile, a nucleophilic addition, a condensation, an intramolecular Michael addition, cyclization, and aromatization. Delightfully, both palladium acetate and supported palladium nanoparticles catalyzed this reaction with similar catalytic performance.

The solvothermal synthesis and characterization of quaternary arsenic chalcogenides CsTMAsQ (TM = Hg, Cd; Q = S, Se) using Cs as a structure directing agent: from 1D anionic chains to 2D anionic layers.

Four new quaternary transition metal arsenic chalcogenide Cs-TM-As-Q compounds (TM = Hg, Cd; Q = S, Se) were synthesized using different mixed solvents. A 1,4-diaminobutane(1,4-dab)/water mixed solvent system was used to solvothermally synthesize the selenoarsenates CsTMAsSe (TM = Hg (1), Cd (2)). In 1, the eight-membered ring anion chain consists of trigonal-planar [HgSe] and trigonal-pyramid [AsSe].

A dual role for acetohydrazide in Pd-catalyzed controlled C(sp)-H acetoxylation of aldehydes.

The palladium catalyzed aldehyde directed acetoxylation of C(sp)-H bonds was realized by a transient directing group approach for the first time. Crucial to the successful outcome of this reaction is the dual role of acetohydrazide as a directing group for the catalytic C(sp)-H activation process and as a protecting group for the CHO functional group. The applicable methodology exhibits good functional group tolerance and occurs readily under mild conditions.

Heterogeneous Suzuki-Miyaura coupling of heteroaryl ester chemoselective C(acyl)-O bond activation.

A site-selective supported palladium nanoparticle catalyzed Suzuki-Miyaura cross-coupling reaction with heteroaryl esters and arylboronic acids as coupling partners was developed. This methodology provides a heterogeneous catalytic route for aryl ketone formation C(acyl)-O bond activation of esters by successful suppression of the undesired decarbonylation phenomenon. The catalyst can be reused and shows high activity after eight cycles.

Chemical synthesis and functional characterization of a new class of ceramide analogues as anti-cancer agents.

Deregulation of ceramide metabolism is a hallmark of human cancer. Ceramide analogues thereby represent a new class of anti-cancer agents. We aimed at developing effective and low toxic ceramide analogues and synthesized a new class of ceramide analogues starting from l-threonine.

Transesterification of (hetero)aryl esters with phenols by an Earth-abundant metal catalyst.

Readily available and inexpensive Earth-abundant alkali metal species are used as efficient catalysts for the transesterification of aryl or heteroaryl esters with phenols which is a challenging and underdeveloped transformation. The simple conditions and the use of heterogeneous alkali metal catalyst make this protocol very environmentally friendly and practical. This reaction fills in the missing part in transesterification reaction of phenols and provides an efficient approach to aryl esters, which are widely used in the synthetic and pharmaceutical industry.

One pot synthesis of diarylfurans from aryl esters and PhI(OAc)2 via palladium-associated iodonium ylides.

The example of palladium-catalyzed intermolecular cyclization for the synthesis of various diarylfurans in which one of the aromatic rings originates from the phenolic part of the starting ester and the other one from PhI(OAc)2 has been reported. The reaction is carried out through two steps: the rearrangement of palladium-associated iodonium ylides to form o-iodo diaryl ether and then palladium catalyzed intramolecular direct arylation. This reaction can tolerate a variety of functional groups and is alternative or complementary to the previous methods for the synthesis of diarylfurans.

Energy-efficient green catalysis: supported gold nanoparticle-catalyzed aminolysis of esters with inert tertiary amines by C-O and C-N bond activations.

Catalyzed by supported gold nanoparticles, an aminolysis reaction between various aryl esters and inert tertiary amines by C-O and C-N bond activations has been developed for the selective synthesis of tertiary amides. Comparison studies indicated that the gold nanoparticles could perform energy-efficient green catalysis at room temperature, whereas Pd(OAc)2 could not.

Aminolysis of aryl ester using tertiary amine as amino donor via C-O and C-N bond activations.

An aminolysis reaction between various aryl esters and inert tertiary amines by C-O and C-N bond activations has been developed for the selective synthesis of a broad scope of tertiary amides under neutral and mild conditions. The mechanism may undergo the two key steps of oxidative addition of acyl C-O bond in parent ester and C-N bond cleavage of tertiary amine via an iminium-type intermediate.

Transesterification for synthesis of carboxylates using aldehydes as acyl donors via C-H and C-O bond activations.

A new type of transesterification between aryl, heteroaryl, alkyl N-heteroarene-2-carboxylates and various aldehydes by C-H and C-O bond activations has been developed for the synthesis of versatile carboxylates. A possible mechanism containing oxidative addition of acyl-O bond in parent ester and radical cleavage of sp(2) C-H bond in aldehyde is proposed.