Synthesis, Structure, and Reactivity of a Gallylene Derivative Bearing a Phenalenyl-Based Ligand.

Phenalenyl-based N,N-bidentate ligand-stabilized monovalent gallium(I) complex 1 was synthesized and characterized by NMR spectroscopies, single-crystal X-ray diffraction, and theoretical calculations. In solution, complex 1 has a high thermal stability at 80 °C, with an absorption maximum at 505 nm. Complex 1 promotes the oxidative addition of I-I, Si-Cl, C-I, and S-S bonds and oxidative cyclization with various π components. Complex 1 can also coordinate to a tungsten complex to form a Ga-W bond.

Open-Shell Germylene Stabilized by a Phenalenyl-Based Ligand.

An open-shell germylene 1 stabilized by a phenalenyl-based bidentate ligand was synthesized and characterized. Because of the high thermal stability originating from spin delocalization over the phenalenyl moiety, it was possible to isolate compound 1 in crystalline form by sublimation at ca. 300 °C. Electron spin resonance (ESR) spectra, crystallographic analysis, theoretical calculations, and reactivities with carbon radicals suggest that the spin of 1 is distributed on the phenalenyl moiety, while 1 reacted with C2Cl6, PhSSPh, and p-benzoquinone at the germanium center to form Ge-E (E = Cl, S, O) bonds. Furthermore, compound 1 is featured by its reactivity as a "formal germylyne", which allows for the formation of three new σ-bonds or one σ-bond with metal complexation on the germanium center.

Cationic Rhodium(I) Tetrafluoroborate Catalyzed Intramolecular Carbofluorination of Alkenes via Acyl Fluoride C-F Bond Activation.

The C-F bond of acyl fluorides can be cleaved and added across tethered alkenes in the presence of a cationic rhodium(I) tetrafluoroborate catalyst. This 1,2-carbofluorination reaction offers a powerful method for the synthesis of tertiary alkyl fluoride derivatives with an atom economy of 100 %. Mechanistic studies indicate that the concerted action of a rhodium cation and a tetrafluoroborate anion is key for the success of this catalytic cleavage and formation of C-F bonds in a controlled manner.

Palladium-Catalyzed Unimolecular Fragment Coupling of N-Allylamides via Elimination of Isocyanate.

Transition metal-catalyzed unimolecular fragment coupling (UFC) is defined as processes that forge new chemical bonds through the extrusion of molecules, such as CO and CO2, and the subsequent recombination of the remaining fragments. Herein, we report on a new UFC reaction that involves the palladium-catalyzed elimination of an isocyanate fragment from an amide, with the formation of carbon-carbon and carbon-heteroatom bonds. An organometallic intermediate that is relevant to the catalytic reaction was characterized by X-ray crystallography. This UFC reaction enables the late-stage transformation of an amide functionality, allowing amides to be used as a convertible directing or protecting group.

Palladium-Catalyzed Siloxycyclopropanation of Alkenes Using Acylsilanes.

Currently, catalytically transferable carbenes are limited to electron-deficient and neutral derivatives, and electron-rich carbenes bearing an alkoxy group (i.e., Fischer-type carbenes) cannot be used in catalytic cyclopropanation because of the lack of appropriate carbene precursors. We report herein that acylsilanes can serve as a source of electron-rich carbenes under palladium catalysis, enabling cyclopropanation of a range of alkenes. This reactivity profile is in sharp contrast to that of metal-free siloxycarbenes, which are unreactive toward normal alkenes. The resulting siloxycyclopropanes serve as valuable homoenolate equivalents, allowing rapid access to elaborate ß-functionalized ketones.

Nickel-Catalyzed Addition of C-C Bonds of Amides to Strained Alkenes: The 1,2-Carboaminocarbonylation Reaction.

C(aryl)-C(═O) bonds of aryl amides can be activated and added across alkenes with the aid of a nickel catalyst. This 1,2-carboaminocarbonylation reaction enables the dicarbofunctionalization of alkenes with an atom economy of 100%.

Localization of Chronic Pain in Postmastectomy Patients: A Prospective Comparison Between Patients With and Without Breast Reconstruction.

BACKGROUND: After breast surgery with or without immediate reconstruction, chronic pain can be a major problem for patients. However, few studies have examined the details of the sites of long-lasting postoperative pain. In this study, we specified the postoperative pain location after breast surgery, including reconstruction, to find ways to improve surgical procedures or provide effective pain relief. METHODS: The subjects were 205 Japanese women undergoing mastectomy or breast reconstruction with a tissue expander (TE)/implant or a deep inferior epigastric perforator (DIEP) flap. Patients were asked whether they had pain in different parts of the body at 1 year after surgery. Differences were assessed by cross-tabulation and χ2 statistics. RESULTS: Surveys were completed by 157 subjects. Deep inferior epigastric perforator flap cases had significantly more pain and TE/Imp cases had significantly less pain in the medial breast, upper breast, breast upper medial quadrant, and abdomen (P = 0.006, P = 0.006, P < 0.001, P < 0.001, respectively). In the neck area, pain in TE/Imp cases was significantly worse than that in all other patients (P = 0.025). There was no significant difference in chronic pain in any other body regions among the mastectomy only, TE/Imp, and DIEP flap groups. CONCLUSIONS: The results of the present study revealed that the localization of prolonged postoperative pain after breast surgery differs depending on the surgical procedure. In DIEP flap reconstruction, there was a marked tendency for pain in the inner and upper chest and in the abdomen, whereas TE/IMP surgery resulted in pain around the neck of the affected side. These findings may help improve surgical methods and establish effective pain relief that focuses on the identified pain areas.

Molecular and Spin Structures of a Through-Space Conjugated Triradical System.

A through-space conjugated multi-phenalenyl triradical 1 a has been prepared and characterized. Partial occupancy of doubly degenerate molecular orbitals in 1 a leads to Jahn-Teller distortion, creating a molecular skeleton in which C2v doublet states are lower in energy than undistorted D3h doublet and quartet states. Triradical 1 a exists in an acute form in the solution state, whereas it adopts a preferred obtuse form in the solid state. The results of the investigation show that these two distorted forms are reversibly interconverted by thermal energy.

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.

Synthesis and Characterization of 1-Hydroxy-4,5-arene-Fused Tropylium Derivatives.

The properties of 1-hydroxy-4,5-arene-fused tropyliums were assessed based on experimental and theoretical investigations. An X-ray crystallographic analysis revealed a decrease of bond alternation in the seven-membered ring of 1-hydroxy-4,5-benzotropylium derivatives compared with that of the parent 4,5-benzotropones, which is indicative of an increase in aromaticity upon protonation. NICS and AICD calculations also supported the increased aromaticity of 1-hydroxy-4,5-arene-fused tropylium. The pKa values for a series of 1-hydroxy-4,5-arene-fused tropylium derivatives were also determined.

Synthesis of 4,5-Benzotropone π Complexes of Iron, Rhodium, and Iridium and Their Potential Use in Catalytic Borrowing-Hydrogen Reactions.

The syntheses of rhodium, iridium, and iron π complexes bearing 4,5-benzotropone ligands are reported. X-ray crystallographic analyses revealed that a tropone core coordinates to a metal center in a η4 manner with a tub-form geometry. Some of the benzotropone π complexes exhibited catalytic activity for N-alkylation of aniline by borrowing hydrogen.

A Medical Tattooing Technique for Enhancing the Three-Dimensional Appearance of the Nipple-Areola Complex After Flap-Based Nipple Reconstruction.

INTRODUCTION: Medical tattooing is a critical reconstructive component in the surgical process for good esthetic outcomes and improved patient satisfaction. There are many nipple reconstruction methods that use a local flap, but reduced post-operative nipple projection is a common problem. Here, we report a modified tattooing method (3D-E tattoo) that enhances the three-dimensional appearance of the nipple-areola complex (NAC), including Montgomery glands, after flap-based nipple reconstruction. METHODS: The subjects were 110 consecutive patients who underwent nipple reconstruction using the C-V flap technique between April 2017 and June 2019. Of these patients, 49 received traditional medical tattooing (Group T) and 61 underwent 3D-E tattoo (Group 3D). A 10-point subjective evaluation of the 3D appearance of the reconstructed NAC was performed, and the scores were compared between the groups. RESULTS: The procedure time for 3D-E tattoo was about 5 minutes longer than that for traditional tattooing. The average score in Group 3D of 7.8/10 was significantly higher than that of 6.4/10 in Group T. CONCLUSION: Application of 3D techniques or "realism" in tattoo artistry has significant potential to improve the esthetic outcomes of reconstructive surgery. Adoption of simple technical skills to produce a more realistic 3D NAC permitted a symmetrical appearance to be reconstructed. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

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 Decarbonylation of Acylsilanes.

Nickel-catalyzed decarbonylation of acylsilanes is developed. In sharp contrast to cross-coupling reactions of acylsilanes, in which the silyl group serves as a leaving group, the silyl group is retained in the product in this decarbonylation reaction. Although the strong binding of the dissociated CO to the nickel center frequently hinders catalyst turnover in nickel-mediated decarbonylative reactions, this reaction can be catalyzed by nickel complexes bearing a CO ligand.

Nonplanar Butterfly-Shaped π-Expanded Pyrrolopyrroles.

Large aza-analogues of curved polycyclic aromatic hydrocarbons with a double-helicene structure present unique features for molecular photonics. We present the preparation and characterization of three such structures. The synthesis of these heterocyclic nanographenes involves only a few high-yield steps that use readily available starting materials. X-ray analysis revealed that each of these new dyes has three conformational isomers: one diastereoisomer in a meso form and two enantiomers in twisted forms [(P,P)] and [(M,M)]. The low energy barriers between the conformers, however, prevent their separation by using chiral HPLC, and the NMR spectra show only one set of signals for each of these curved compounds. Density functional theory (DFT) calculations quantify the small energy difference and the small energy barriers between the chiral and meso forms, which fully supports the experimental results. Their optical absorption lacks any sensitivity to the solvent environment, whereas their fluorescence features exhibit pronounced solvatochromism. This rarely observed solvatofluorochromism of centrosymmetric molecules without either electron-withdrawing groups or -donating substituents was probed by using time-resolved spectroscopy. These studies suggest that, similar to 9,9'-bianthryl, the nonpolar locally excited state shows negligible solvatochromism, whereas the charge-transfer state is sensitive to solvent polarity.

Cu(II) detection by a fluorometric probe based on thiazoline-amidoquinoline derivative and its application to water and food samples.

Two novel fluorescent probes for Cu2+ detection have been developed based on thiazoline-quinoline conjugates bearing a 4-ethynyl-N,N-dimethylaniline unit (QT1 and QT2). QT2 exhibits instantaneous fluorescence quenching of Cu2+ with an emissive change from bright orange to arctic blue under UV light irradiation (365 nm). The plots of I0/I against Cu2+ concentrations show a good linear relationship that ranges from 0 to 50 µM with a coefficient of determination (R2) = 0.9906 and a limit of detection (LOD) of 76 nM, which is considered low (4.84 ppb). A 1:1 complexation between QT2 and Cu2+ was confirmed by UV-Vis titration, ESI-MS, and SC-XRD. The QT2·Cu2+ complex was dissociated by the addition of EDTA. The fluorescence quenching mechanism involves the ligand-to-metal charge transfer (LMCT) of a paramagnetic Cu2+ complex. The QT2 probe on a paper-based strip was used to determine the amount of Cu2+ in water and food samples (shiitake mushrooms and oysters).

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.

Local probe-induced structural isomerization in a one-dimensional molecular array.

Synthesis of one-dimensional molecular arrays with tailored stereoisomers is challenging yet has great potential for application in molecular opto-, electronic- and magnetic-devices, where the local array structure plays a decisive role in the functional properties. Here, we demonstrate the construction and characterization of dehydroazulene isomer and diradical units in three-dimensional organometallic compounds on Ag(111) with a combination of low-temperature scanning tunneling microscopy and density functional theory calculations. Tip-induced voltage pulses firstly result in the formation of a diradical species via successive homolytic fission of two C-Br bonds in the naphthyl groups, which are subsequently transformed into chiral dehydroazulene moieties. The delicate balance of the reaction rates among the diradical and two stereoisomers, arising from an in-line configuration of tip and molecular unit, allows directional azulene-to-azulene and azulene-to-diradical local probe structural isomerization in a controlled manner. Furthermore, our theoretical calculations suggest that the diradical moiety hosts an open-shell singlet with antiferromagnetic coupling between the unpaired electrons, which can undergo an inelastic spin transition of 91 meV to the ferromagnetically coupled triplet state.

Nickel-catalyzed skeletal transformation of tropone derivatives via C-C bond activation: catalyst-controlled access to diverse ring systems.

We report herein on nickel-catalyzed carbon-carbon bond cleavage reactions of 2,4,6-cycloheptatrien-1-one (tropone) derivatives. When a Ni/N-heterocyclic carbene catalyst is used, decarbonylation proceeds with the formation of a benzene ring, while the use of bidentate ligands in conjunction with an alcohol additive results in a two-carbon ring contraction with the generation of cyclopentadiene derivatives. The latter reaction involves a nickel-ketene complex as an intermediate, which was characterized by X-ray crystallography. The choice of an appropriate ligand allows for selective synthesis of four different products via the cleavage of a seven-membered carbocyclic skeleton. Reaction mechanisms and ligand-controlled selectivity for both types of ring contraction reactions were also investigated computationally.