Synthesis of γ-Lactams from Acrylamides by Single-Carbon Atom Doping Annulation.

A protocol for single-carbon atom doping annulation is reported, which enables the conversion of acrylamides into homologated γ-lactams through the cleavage of two σ-bonds and the formation of four new σ-bonds at the single carbon center. The key strategy is the use of N-heterocyclic carbenes as an atomic carbon equivalent by acting as carbon atom donors through the loss of a 1,2-diimine moiety. Experimental and computational studies reveal that the reaction proceeds through a spirocyclic intermediate, followed by the disassembly of the N-heterocyclic carbene skeleton via proton transfer.

Non-Stabilized Vinyl Anion Equivalents from Styrenes by N-Heterocyclic Carbene Catalysis and Its Use in Catalytic Nucleophilic Aromatic Substitution.

A protocol for the catalytic nucleophilic activation of unactivated styrenes is reported, which enables the generation of a non-stabilized alkenyl anion equivalent as a transient intermediate. In the reaction, N-heterocyclic carbenes add across styrenes to generate ylide intermediates, which can then be used in intramolecular nucleophilic aromatic substitution reactions of aryl fluorides, chlorides, and methyl ethers. The method allows for straightforward access to complex polyaromatic compounds.

Overlooked Factors Required for Electrolyte Solvents in Li-O2 Batteries: Capabilities of Quenching 1 O2 and Forming Highly-Decomposable Li2 O2.

Although sufficient tolerance against attack by superoxide radicals (O2 - ) has been mainly recognized as an important property for Li-O2 battery (LOB) electrolytes, recent evidence has revealed that other critical factors also govern the cyclability, prompting a reconsideration of the basic design guidelines of LOB electrolytes. Here, we found that LOBs equipped with a N,N-dimethylacetamide (DMA)-based electrolyte exhibited better cyclability compared with other standard LOB electrolytes. This superior cyclability is attributable to the capabilities of quenching 1 O2 and forming highly decomposable Li2 O2 . The 1 O2 quenching capability is equivalent to that of a tetraglyme-based electrolyte containing a several millimolar concentration of a typical chemical quencher. Based on these overlooked factors, the DMA-based electrolyte led to superior cyclability despite its lower O2 - tolerance. Thus, the present work provides a novel design guideline for the development of LOB electrolytes.

Three-Component Coupling of Acyl Fluorides, Silyl Enol Ethers, and Alkynes by P(III)/P(V) Catalysis.

We report herein on the phosphine-catalyzed hydrovinylation reaction by three-component coupling of acyl fluorides, silyl enol ethers, and alkynoates. The key to the success of the reaction is the formal transmetalation between pentacoordinate P(V) species (i.e., fluorophosphorane) and a silyl enol ether, which allows for C-C bond formation between the polarity-mismatched sites. The bond formation that cannot be attained even by transition metal catalysis is accomplished by a P(III)/P(V) manifold.

Phosphine-Catalyzed Intermolecular Acylfluorination of Alkynes via a P(V) Intermediate.

We report the phosphine-catalyzed intermolecular carbofluorination of alkynes using acyl fluorides as fluorinating reagents. This reaction promises to be a useful method for the synthesis of highly substituted monofluoroalkene derivatives since acyl fluorides can be easily prepared from the corresponding carboxylic acid derivatives and the reaction proceeds under ambient conditions without the need for a transition-metal catalyst. Experimental and computational studies indicate that a five-coordinate fluorophosphorane is involved as the key intermediate in the fluorination step.

Nickel-Catalyzed Decarboxylation of Aryl Carbamates for Converting Phenols into Aromatic Amines.

Herein, we describe a new catalytic approach to accessing aromatic amines from an abundant feedstock, namely phenols. The most reliable catalytic method for converting phenols to aromatic amines uses an activating group, such as a trifluoromethane sulfonyl group. However, this activating group is eliminated as a leaving group during the amination process, resulting in significant waste. Our nickel-catalyzed decarboxylation reaction of aryl carbamates forms aromatic amines with carbon dioxide as the only byproduct. As this amination proceeds in the absence of free amines, a range of functionalities, including a formyl group, are compatible. A bisphosphine ligand immobilized on a polystyrene support (PS-DPPBz) is key to the success of this reaction, generating a catalytic species that is significantly more active than simple nonsupported variants.

Effect of short foot exercise on lower-limb motor control function during single-leg standing in university students with flatfoot: A randomized controlled trial.

INTRODUCTION: Intrinsic foot muscles (IFMs) play an important role in lower-limb motor control, including biomechanics and neuromuscular control function. Short foot exercise (SFE) and toe curl exercise (TC) are methods used to train the IFMs, but their effect on lower-limb motor control has not been reported in previous studies. This study evaluated the effects of SFE and TC on lower-limb motor control function during single-leg standing (SLS). TRIAL DESIGN: Randomized control trial. METHOD: Thirty-six participants with flatfoot were randomly assigned to the SFE or TC group and performed exercise for 8 weeks. The assessment items were navicular drop test, toe grip strength (TGS), plantar sensation, and SLS. In the SLS assessment, we measured the mean center of pressure (COP) amplitude in the anteroposterior (AP) and mediolateral (ML) directions, onset time of gluteus maximus (G. max) and gluteus medius (G. med), angle of forefoot/hindfoot protonation and hip adduction, and lateral pelvic shift. Mixed-model repeated-measures analysis of variance and Bonferroni corrections were performed in statistical analysis. RESULTS: The SFE group showed significant differences between pre- and post-intervention for TGS (p < 0.001), COP ML (p = 0.039), and onset times of G. max (p = 0.015), and G. med (p < 0.001). The TC group showed no significant differences in all assessment items. CONCLUSION: Our finding suggests that SFE contributes to lower neuromuscular control function in people with flatfoot. TRIAL REGISTRATION: UMIN000049963.

Fluorinated Amide-Based Electrolytes Induce a Sustained Low-Charging Voltage Plateau under Conditions Verifying the Feasibility of Achieving 500 Wh kg-1 Class Li-O2 Batteries.

Although lithium-oxygen batteries (LOBs) hold the promise of high gravimetric energy density, this potential is hindered by high charging voltages. To ensure that the charging voltage remains low, it is crucial to generate discharge products that can be easily decomposed during the successive charging process. In this study, we discovered that the use of amide-based electrolyte solvents containing a fluorinated moiety can notably establish a sustained voltage plateau at low-charging voltages at around 3.5 V. This occurs under conditions that can verify the feasibility of achieving a benchmark energy density value of 500 Wh kg-1. Notably, the achievement of the low-voltage plateau was accomplished solely by relying on the intrinsic properties of the electrolyte solvent. Indeed, synchrotron X-ray diffraction measurements have shown that the use of fluorine-containing amide-based electrolyte solvents results in the formation of highly decomposable discharge products, such as amorphous and Li-deficient lithium peroxides.

1,2-Diacylation of Alkynes Using Acyl Fluorides and Acylsilanes by P(III)/P(V) Catalysis.

We report herein the phosphine-catalyzed 1,2-diacylation of alkynes using acyl fluorides and acylsilanes as acyl sources. The key to the success of the reaction is a formal oxidative addition-ligand metathesis-reductive elimination cycle based on phosphine redox catalysis, which allows for the installation of two different acyl groups into an alkyne in a regioselective manner.

Single-carbon atom transfer to α,ß-unsaturated amides from N-heterocyclic carbenes.

Single-carbon atom transfer reactions are lacking in organic synthesis, partly because of the absence of atomic carbon sources under standard solution-phase conditions. We report here that N-heterocyclic carbenes can serve as atomic carbon donors through the loss of a 1,2-diimine moiety. This strategy is applicable to single-carbon atom transfer to α,ß-unsaturated amides, which can be converted into homologated γ-lactams through the formation of four single bonds to one carbon center in one operation.

N-Heterocyclic Carbene-Catalyzed Truce-Smiles Rearrangement of N-Arylacrylamides via the Cleavage of Unactivated C(aryl)-N Bonds.

We report on the N-heterocyclic carbene (NHC)-catalyzed Truce-Smiles rearrangement of aniline derivatives, in which an unactivated C(aryl)-N bond is cleaved, leading to the formation of a new C(aryl)-C bond. The key to the success of this reaction is the utilization of a highly nucleophilic NHC, which enables the formation of a highly nucleophilic ylide intermediate that is generated from an α,ß-unsaturated amide.

Aryne-Induced SNAr/Dearylation Strategy for the Synthesis of Fluorinated Dibenzophospholes from Triarylphosphines via a P(V) Intermediate.

We report on a method for the synthesis of fluorinated dibenzophospholes using triarylphosphine via dearylative annulation with an aryne. This intermolecular annulation allows the preparation of a variety of fluorinated dibenzophospholes from simple building blocks. The key to the success of this dearylative annulation is the formation of a five-coordinated tetraarylfluorophosphorane. In this work, we successfully synthesized stable tetraarylfluorophosphorane, the structure of which was unambiguously determined by X-ray crystallography.

Cyclization of Bisphosphines to Phosphacycles via the Cleavage of Two Carbon-Phosphorus Bonds by Nickel Catalysis.

The nickel-catalyzed cyclization of bisphosphine derivatives to form various phosphacycles is reported. The reaction proceeds via the cleavage of two carbon-phosphorus bonds of the bisphosphine. Unlike the previously reported palladium catalysts, the use of nickel as a catalyst allows for the cyclization that requires C(alkyl)-P bond cleavage. A phospha-nickelacycle intermediate was successfully isolated and characterized by X-ray crystallography.

Synthesis and Isomerization Behavior of a Macrocycle with Four Photoresponsive Moieties.

The macrocycle 1 containing four photoresponsive fluorenylidene moieties was designed. The EZEZ form of 1, 1 EZEZ, was selectively produced. Reversible photochemical isomerization between 1 EZEZ and 1 ZZZZ was achieved, the extent of which was dependent on the light source used. Furthermore, the intermediate 1 EZZZ was selectively isomerized to 1 ZZZZ thermally and photochemically.