Palladium-Catalyzed Decarboxylative Coupling of Alkynyl Carboxylic Acids and Alkenyl Tosylates for the Synthesis of Enynones

A palladium-catalyzed decarboxylative coupling reaction was developed for the synthesis of 3-(1-alkynyl)-2-cyclohexen-1-ones. A variety of alkynyl carboxylic acids were coupled with 3-oxocyclohexenyl tosylates to afford the corresponding enynones in good to excellent yields. The developed catalytic system is phosphine free and showed good tolerance toward various functionalities such as chloride, cyano, nitro, ester, aldehyde, and alcohol groups. In addition, phenylpropiolic acid exhibited higher reactivity in the reaction with alkenyl toslyate than phenyl acetylene

Synthesis of (+)-Xylogiblactones B and C through a Kinetic Resolution of the Allenoate γ‑Addition: Stereochemical Establishment

Concise syntheses of naturally occurring γ-butenolides (+)-xylogiblactones B and C have been achieved for the first time starting from commercial methyl crotonate in 5–8 steps. The synthetic course involves allenoate γ-addition to racemic aldehydes through a kinetic resolution to establish the required stereochemical framework as center and axial chirality and subsequent oxacyclization via gold catalysis to complete the (+)-xylogiblactone skeleton. Both key transformations proceed in a regio- and stereospecific manner. This outcome relies on finding an efficient synthetic method for racemic aldehydes as precursors for the kinetic resolution. Completion of the synthesis provides stereochemical clarification for (+)-xylogiblactones B and C

Enhanced Photocurrent of Transparent CuFeO₂ Photocathodes by Self-Light-Harvesting Architecture

Efficient sunlight-driven water-splitting devices can be achieved by using an optically and energetically well-matched pair of photoelectrodes in a tandem configuration. The key for maximizing the photoelectrochemical efficiency is the use of a highly transparent front photoelectrode with a band gap below 2.0 eV. Herein, we propose two-dimensional (2D) photonic crystal (PC) structures consisting of a CuFeO₂-decorated microsphere monolayer, which serve as self-light-harvesting architectures allowing for amplified light absorption and high transparency. The photocurrent densities are evaluated for three CuFeO₂ 2D PC-based photoelectrodes with microspheres of different sizes. The optical analysis confirmed the presence of a photonic stop band that generates <i>slow light</i> and at the same time amplifies the absorption of light. The 410 nm sized CuFeO₂-decorated microsphere 2D PC photocathode shows an exceptionally high visible light transmittance of 76.4% and a relatively high photocurrent of 0.2 mA cm^–2 at 0.6 V vs a reversible hydrogen electrode. The effect of the microsphere size on the carrier collection efficiency was analyzed by in situ conductive atomic force microscopy observation under illumination. Our novel synthetic method to produce self-light-harvesting nanostructures provides a promising approach for the effective use of solar energy by highly transparent photocathodes

Nickel-Catalyzed Hiyama-type Decarboxylative Coupling of Propiolic Acids and Organosilanes

A Ni catalytic system was developed for the decarboxylative coupling reaction of alkynyl carboxylic acids with organosilanes. Ni­(acac)₂ and 1,10-phenanthroline showed the best result in the presence of CsF and CuF₂ at 120 °C. This system tolerated the presence of alkyl, alkoxy, halogen, nitro, cyano, ketone, and ester functional groups. Moreover, the reaction with but-2-ynedioic acid and organosilane afforded the corresponding symmetrical diarylalkynes

Comorbidities during or prior to pregnancy.

<p>Comorbidities during or prior to pregnancy.</p

Glucose-lowering therapy during pregnancy in patients with gestational diabetes mellitus (GDM) between 2009 and 2011.

<p>Glucose-lowering therapy during pregnancy in patients with gestational diabetes mellitus (GDM) between 2009 and 2011.</p

Prevalence rate of gestational diabetes mellitus (GDM) between 2009 and 2011.

<p>Prevalence rate of gestational diabetes mellitus (GDM) between 2009 and 2011.</p

Synthesis of Terminal Allenes via a Copper-Catalyzed Decarboxylative Coupling Reaction of Alkynyl Carboxylic Acids

Synthesis of terminal allenes via a copper-catalyzed decarboxylative coupling reaction was developed. Aryl alkynyl carboxylic acid, paraformaldehyde, and dicyclohexylamine were reacted with CuI (20 mol %) in diglyme at 100 °C for 2 h to produce the terminal allene in moderate to good yields. The method showed good functional group tolerance

Key Structural Elements for Cellular Uptake of Acinetobactin, a Major Siderophore of <i>Acinetobacter baumannii</i>

Acinetobactin is a major siderophore utilized by the human pathogen <i>Acinetobacter baumannii</i>. The rapid acquisition of drug resistance by <i>A. baumannii</i> has garnered concern globally. Herein, acinetobactin and systematically generated analogues were prepared and characterized; the binding and cellular delivery of Fe­(III) by the analogues were evaluated. This investigation not only led to the clarification of the physiologically relevant acinetobactin structure but also revealed several key structural elements for its functionality as a siderophore

Molecular Chemistry-Controlled Hybrid Ink-Derived Efficient Cu₂ZnSnS₄ Photocathodes for Photoelectrochemical Water Splitting

To realize economically competitive hydrogen production through photoelectrochemical (PEC) water splitting, it is essential to develop an efficient photoelectrode consisting of earth-abundant constituents in conjunction with low-cost solution processing. Cu₂ZnSnS₄ (CZTS) has received significant attention as a promising photocathode owing to its abundance and good absorption properties. However, the efficiency of the solution-processed CZTS photocathode is not yet comparable to its counterparts. Here, a hybrid ink, obtained by careful control of precursor mixing order, was used to produce a highly efficient CZTS photocathode. The molecular chemistry-controlled hybrid ink formulation, particularly the roles of thiourea–Sn²⁺ complexation, was elucidated by liquid Raman spectroscopy. The hybrid ink-derived CZTS thin films modified with conformal coating of an n-type TiO₂/CdS double layer and a Pt electrocatalyst achieved an exceptionally high photocurrent of 13 mA cm^–2 at −0.2 V versus a reversible hydrogen electrode under 1 sun illumination. The modified photocathodes showed relatively stable H₂ production with faradaic efficiency close to unity