Cobalt-Catalyzed Intramolecular Markovnikov Hydrocarbonylation of Unactivated Alkenes via Hydrogen Atom Transfer.

A cobalt-catalyzed intramolecular Markovnikov hydroalkoxycarbonylation and hydroaminocarbonylation of unactivated alkenes has been developed, enabling highly chemo- and regioselective synthesis of α-alkylated γ-lactones and α-alkylated γ-lactams in good yields. The mild reaction conditions allow use of mono-, di- and trisubstituted alkenes bearing a variety of functional groups. Preliminary mechanistic studies suggest the reaction proceeds through a CO-mediated hydrogen atom transfer (HAT) and radical-polar crossover (RPC) process, in which a cationic acylcobalt(IV) complex is proposed as the key intermediate.

Copper-Catalyzed Protoarylation of -Difluoroallenes.

A copper-catalyzed protoarylation of -difluoroallenes with aryl boronic esters has been developed, enabling highly regioselective synthesis of -difluoroalkenes in high yields. The mild reaction conditions allow for a variety of functional groups to be tolerated, and the reaction can be extended to protoalkenylation of -difluoroallenes. The synthetic utility of this method has been demonstrated in gram-scale operation as well as synthesis of chiral -difluoroalkenes bearing γ-carbon stereogenic centers in moderate enantioselectivity using a chiral bidentate phosphine ligand with a copper catalyst.

Copper-Catalyzed Carbonylative Coupling of Alkyl Halides.

Transition metal-catalyzed carbonylation reactions represent a direct and atom-economical approach to introduce oxygen functionality into organic compounds, with CO acting as an inexpensive and readily available C1 feedstock. Despite the long history of carbonylation catalysis, including many processes that have been industrialized at bulk scale, there remain several challenges to tackle. For example, noble metals such as Pd, Rh, and Ir are typically used as catalysts for carbonylation reactions, rather than earth-abundant alternatives.

One-Step Synthesis of Acylboron Compounds via Copper-Catalyzed Carbonylative Borylation of Alkyl Halides*.

A copper-catalyzed carbonylative borylation of unactivated alkyl halides has been developed, enabling efficient synthesis of aliphatic potassium acyltrifluoroborates (KATs) in high yields by treating the in situ formed tetracoordinated acylboron intermediates with aqueous KHF . A variety of functional groups are tolerated under the mild reaction conditions, and primary, secondary, and tertiary alkyl halides are all applicable. In addition, this method also provides facile access to N-methyliminodiacetyl (MIDA) acylboronates as well as α-methylated potassium acyltrifluoroborates in a one-pot manner.

C-C and C-X coupling reactions of unactivated alkyl electrophiles using copper catalysis.

Transition metal-catalysed cross-coupling reactions are widely used for construction of carbon-carbon and carbon-heteroatom bonds. However, compared to aryl or alkenyl electrophiles, the cross-coupling of unactivated alkyl electrophiles containing β hydrogens remains a challenge. Over the past few years, the use of suitable ligands such as bulky phosphines or N-heterocyclic carbenes (NHCs) has enabled reactions of unactivated alkyl electrophiles not only limited to the traditional cross-coupling with Grignard reagents, but also including a diverse range of organic transformations via either S2 or radical pathways.

[Effects of Different Coagulants on Co-manganese Oxides Filter Media for Removing Ammonium and Manganese from Surface Water in Summer and Autumn].

Under high temperatures in summer and autumn, the effects of FeCl, PFC, and PAFC on co-manganese oxides filter media for removing ammonium and manganese from surface water were investigated. The results showed that FeCl can be hydrolyzed easily, thus reducing the pH of the water and the residual iron in the water were not conducive to the removal of ammonium and manganese. Transforming the coagulant FeCl into PFC can effectively recover the removal effect of ammonium and manganese.

Cu-Catalyzed Carbonylative Silylation of Alkyl Halides: Efficient Access to Acylsilanes.

A Cu-catalyzed carbonylative silylation of unactivated alkyl halides has been developed, enabling efficient synthesis of alkyl-substituted acylsilanes in high yield. A variety of functional groups are tolerated under the mild reaction conditions, and primary, secondary, and tertiary alkyl halides are all applicable. The practical utility of this method has been demonstrated in the synthesis of acylsilanes bearing different silyl groups as well as reduction of a product to the corresponding α-hydroxylsilane in one pot.

Heterobimetallic Control of Regioselectivity in Alkyne Hydrostannylation: Divergent Syntheses of α- and ( E) -β -Vinylstannanes via Cooperative Sn-H Bond Activation.

Cooperative Sn-H bond activation of hydrostannanes (BuSnH) by tunable heterobimetallic (NHC)Cu-[M] catalysts ([M] = FeCp(CO) or Mn(CO)) enables the catalytic hydrostannylation of terminal alkynes under mild conditions, with Markovnikov/anti-Markovnikov selectivity controlled by the Cu/M pairing. By using the IMesCu-FeCp(CO) catalyst, a variety of α-vinylstannanes were produced from simple alkyl-substituted alkynes and BuSnH in high yield and good regioselectivity; these products are challenging to access under mononuclear metal-catalyzed hydrostannylation conditions. In addition, reversed regioselectivity was observed for aryl-substituted alkynes under the Cu/Fe-catalyzed conditions, affording the ( E)-β -vinylstannanes as major products.

A case report and analysis of hypertrophic obstructive cardiomyopathy causing an illusion of aortic stenosis.

Rationale: This study aimed to report a case of hypertrophic obstructive cardiomyopathy causing an illusion of aortic stenosis on imaging.

Patient Concerns: A 71-year-old woman presented with chest tightness after activity for 1 year and coughing for 2 months. A systolic 3/6 grade murmur was found in the third intercostals of the left border of sternum.

Copper-Catalyzed Borocarbonylative Coupling of Internal Alkynes with Unactivated Alkyl Halides: Modular Synthesis of Tetrasubstituted β-Borylenones.

Reported is a general procedure to synthesize tetrasubstituted enones, which are borylated in the β-position, using a copper-catalyzed four-component coupling reaction of simple chemical feedstocks: internal alkynes, alkyl halides, bis(pinacolato)diboron (B pin ), and CO. A broad scope of highly functionalized β-borylated enones, a largely unknown class of organic compounds, can be accessed efficiently using this method. The synthesis of all-carbon tetrasubstituted enones was realized by employing the β-borylated enone unit, without purification, in a Suzuki-Miyaura coupling.

Gallic acid-assisted synthesis of Pd uniformly anchored on porous N-rGO as efficient electrocatalyst for microbial fuel cells.

The sluggish kinetic rate-limiting oxygen reduction reaction (ORR) at the cathode remains the foremost issue hindering the commercialization of microbial fuel cells (MFCs). Utilization of the effect of micromolecule conjugation and the synergistic effect between Pd nanoparticles and N-rGO (nitrogen-doped reduced graphene oxide) to stabilize a precious metal onto carbon materials is a promising strategy to design and synthesize highly efficient cathode catalysts. In this study, gallic acid is used to facilitate the coupling of palladium (Pd) with N-rGO to form GN@Pd-GA via a simple hydrothermal process.

Synthesis of Allylic Alcohols via Cu-Catalyzed Hydrocarbonylative Coupling of Alkynes with Alkyl Halides.

We have developed a modular procedure to synthesize allylic alcohols from tertiary, secondary, and primary alkyl halides and alkynes via a Cu-catalyzed hydrocarbonylative coupling and 1,2-reduction tandem sequence. The use of tertiary alkyl halides as electrophiles was found to enable the synthesis of various allylic alcohols bearing α-quaternary carbon centers in good yield with high 1,2-reduction selectivity. Mechanistic studies that suggested a different pathway was operative with tertiary alkyl halides compared with primary and secondary alkyl halides for generating the key copper(III) oxidative adduct.

Enantioselective propargylic [1,3]-rearrangements: copper-catalyzed -to- migrations toward C-N bond formation.

We have identified an enantioselective copper-catalyzed -to- formal [1,3]-rearrangement to form -propargylic-2-pyridones. This enantioconvergent -to- propargylic rearrangement occurs rapidly at ambient temperature and high enantioselectivity is observed for a range of 3-alkyl-substituted substrates. Stereochemical features include a mild kinetic enantioenrichment of the substrate and a non-linear relationship between product and ligand enantiopurity.

Cu/Mn bimetallic catalysis enables carbonylative Suzuki-Miyaura coupling with unactivated alkyl electrophiles.

A bimetallic system consisting of Cu-carbene and Mn-carbonyl co-catalysts was employed for carbonylative C-C coupling of arylboronic esters with alkyl halides, allowing for the convergent synthesis of ketones. The system operates under mild conditions and exhibits complementary reactivity to Pd catalysis. The method is compatible with a wide range of arylboronic ester nucleophiles and proceeds smoothly for both primary and secondary alkyl iodide electrophiles.

Cu-Catalyzed Hydrocarbonylative C-C Coupling of Terminal Alkynes with Alkyl Iodides.

A Cu-catalyzed hydrocarbonylative C-C coupling of terminal alkynes with unactivated alkyl iodides has been developed, enabling highly chemo- and regioselective synthesis of unsymmetrical dialkyl ketones. A variety of functional groups are tolerated, and both primary and secondary alkyl iodides react well. An autotandem sequence of two Cu-catalyzed processes is proposed: first hydrocarbonylative coupling of the alkyne and the alkyl iodide, followed by reduction of the intermediate unsaturated ketone to the saturated product.

Divergent enantioselective synthesis of hapalindole-type alkaloids using catalytic asymmetric hydrogenation of a ketone to construct the chiral core structure.

A divergent enantioselective approach to hapalindole-type alkaloids is described. The route features a ruthenium-catalyzed asymmetric hydrogenation of a ketone DKR to construct the chiral -1-indolyl-2-isopropenylcyclohexane skeleton and a switchable sequence of methylation and acetylation/aldol reaction to access a chiral quaternary stereocenter. (+)-Hapalindole Q (, 13 steps, 5.

Catalytic Nucleophilic Fluorination of Secondary and Tertiary Propargylic Electrophiles with a Copper-N-Heterocyclic Carbene Complex.

A catalytic method for the nucleophilic fluorination of propargylic electrophiles is described. Our protocol involves the use of a Cu(NHC) complex as the catalyst and is suitable for the preparation of secondary and tertiary propargylic fluorides without the formation of isomeric fluoroallenes. Preliminary mechanistic investigations suggest that fluorination proceeds via copper acetylides and that cationic species are involved.

Enantioselective total synthesis of (-)-Δ8-THC and (-)-Δ9-THC via catalytic asymmetric hydrogenation and S(N)Ar cyclization.

The highly efficient asymmetric total syntheses of (-)-Δ(8)-tetrahydrocannabinol ((-)-Δ(8)-THC) (13 steps, 35%) and (-)-Δ(9)-tetrahydrocannabinol ((-)-Δ(9)-THC) (14 steps, 30%) have been developed by using ruthenium-catalyzed asymmetric hydrogenation of racemic α-aryl cyclic ketones via dynamic kinetic resolution and intramolecular S(N)Ar cyclization.