The full control of redox events is of utmost importance to key aspects of molecular synthesis. As a consequence, chemists have recognized the power of electrochemistry for more than a century to govern electron movements for chemical transformations. Despite numerous benefits associated with electrosynthesis, electrical-current-enabled organic transformations have remained for decades largely dormant in academia and industry. However, organic electrosynthesis has recently experienced a considerable renaissance in terms of implementing electrochemical strategies in the synthetic arsenal. To illustrate this unique potential, we have selected four recent representative examples of contemporary organic electrosynthesis that have attracted major attention toward a toolbox for sustainable synthetic chemists.
Ependymal cells (ECs) are multiciliated neuroepithelial cells that line the ventricles of the brain and the central canal of the spinal cord (SC). How ependymal motile cilia are maintained remains largely unexplored. Here we show that zebrafish embryos deficient in Wnt signaling have defective motile cilia, yet harbor intact basal bodies. With respect to maintenance of ependymal motile cilia, plcδ3a is a target gene of Wnt signaling. Lack of Connexin43 (Cx43), especially its channel function, decreases motile cilia and intercellular Ca2+ wave (ICW) propagation. Genetic ablation of cx43 in zebrafish and mice diminished motile cilia. Finally, Cx43 is also expressed in ECs of the human SC. Taken together, our findings indicate that gap junction mediated ICWs play an important role in the maintenance of ependymal motile cilia, and suggest that the enhancement of functional gap junctions by pharmacological or genetic manipulations may be adopted to ameliorate motile ciliopathy.
C7−H‐functionalized indoles are ubiquitous structural units of biological and pharmaceutical compounds for numerous antiviral agents against SARS‐CoV or HIV‐1. Thus, achieving site‐selective functionalizations of the C7−H position of indoles, while discriminating among other bonds, is in high demand. Herein, we disclose site‐selective C7−H activations of indoles by ruthenium(II) biscarboxylate catalysis under mild conditions. Base‐assisted internal electrophilic‐type substitution C−H ruthenation by weak O‐coordination enabled the C7−H functionalization of indoles and offered a broad scope, including C−N and C−C bond formation. The versatile ruthenium‐catalyzed C7−H activations were characterized by gram‐scale syntheses and the traceless removal of the directing group, thus providing easy access to pharmaceutically relevant scaffolds. Detailed mechanistic studies through spectroscopic and spectrometric analyses shed light on the unique nature of the robust ruthenium catalysis for the functionalization of the C7−H position of indoles.
Heterogeneous copper catalysis enabled photoinduced C−H arylations under exceedingly mild conditions at room temperature. The versatile hybrid copper catalyst provided step‐economical access to arylated heteroarenes, terpenes and alkaloid natural products with various aryl halides. The hybrid copper catalyst could be reused without significant loss of catalytic efficacy. Detailed studies in terms of TEM, HRTEM and XPS analysis of the hybrid copper catalyst, among others, supported its outstanding stability and reusability.
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