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This article in Chemical Communications explores the synthesis and reactivity of angle-strained sila-cycloalkynes. The authors present the synthesis of two new examples of these compounds and investigate their reactivity with azides. The results indicate that angle-strain alone is not enough to facilitate cycloaddition at room temperature, which has implications for the field of organic chemistry and chemical biology. The article includes detailed experimental procedures and computational details for further study. Additionally, the document discusses the lack of reaction between a specific sila-cyclooctyne compound and N3Bn at different temperatures. The authors suggest that the slow reaction rate may be due to modest alkyne distortion and the electron-donating effect of the silicon atom. Computational studies support this hypothesis, showing that the activation energies of the reaction increase across the series of compounds, consistent with the experimental rates. In conclusion, the article emphasizes that measurable angle strain alone cannot accurately predict strain-promoted azide-alkyne cycloaddition reactions at room temperature. [Extracted from the article]

The design of polymeric semiconductors exhibiting high electrical conductivity (σ) and thermoelectric power factor (PF) will be vital for flexible large‐area electronics. In this work, four polymers based on diketopyrrolopyrrole (DPP), 2,3‐dihydrothieno[3,4‐b][1,4]dioxine (EDOT), thieno[3,2‐b]thiophene (TT), and 3, 3′‐bis (2‐(2‐(2‐methoxyethoxy) ethoxy) ethoxy)‐2, 2′‐bithiophene (MEET) are investigated as side‐chains, with the MEET polymers newly synthesized for this study. These polymers are systematically doped with tetrafluorotetracyanoquinodimethane (F4TCNQ), CF3SO3H, and the synthesized dopant Cp(CN)3‐(COOMe)3, differing in geometry and electron affinity. The DPP‐EDOT‐based polymer containing MEET as side‐chains exhibits the highest conductivity (σ) ≈700 S cm−1 in this series with the acidic dopant (CF3SO3H). This polymer also shows the lowest oxidation potential by cyclic voltammetry (CV), the strongest intermolecular interactions evidenced by differential scanning calorimetry (DSC), and has the most oxygen‐based functionality for possible hydrogen bonding and ionic screening. Other polymers exhibit high σ ≈300–500 S cm−1 and power factor up to 300 µW m−1 K−2. The mechanism of conductivity is predominantly electronic, as validated by time‐dependent conductance studies and transient thermo voltage monitoring over time, including for those doped with the acid. These materials maintain significant thermal stability and air stability over ≈6 weeks. Density functional theory calculations reveal molecular geometries and inform about frontier energy levels. Raman spectroscopy, in conjunction with scanning electron microscopy (SEM‐EDS) and x‐ray diffraction, provides insight into the solid‐state microstructure and degree of phase separation of the doped polymer films. Infrared spectroscopy enables this study to further quantify the degree of charge transfer from polymer to dopant. [ABSTRACT FROM AUTHOR]

The electrophilic substitution of indoles with tetronic acid and N-acetyltetramic acid mediated by BF3·OEt2 was investigated. This strategy allowed for the preparation of nine indole-substituted furan-2-ones (indolyl-γ-lactones) and 3-pyrrolin-2-ones (indolyl-γ-lactams) and is more straightforward than previously reported synthetic methods. During the course of our investigation, we also discovered a facile synthesis of tetronates and a tetramate via a BF3-mediated addition of alcohols to tetronic acid and N-acetyltetramic acid, respectively. [ABSTRACT FROM AUTHOR]