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Herein, we synthesized guanidine functionalized graphene oxide nanocomposites referred to GO‐GN NCs using hummer's method. GO‐GN NCs was characterized using Fourier‐Transform Infrared Spectroscopy, Powder X‐ray Diffraction, Thermogravimetric Analysis, Raman Spectroscopy, Field Emission Scanning Electron Microscopy, Transmission Electron Microscopy, Brunauer‐Emmett‐Teller (BET) surface area analysis to confirm successful formation of GO‐GN NCs catalysts. The catalytic performance for GO‐GN NCs was evaluated for Knoevenagel and Aldol condensation reaction in aqueous medium at ambient condition and result shows that it could be used as a highly efficient, stable, and durable catalyst. In addition, it has another feature such as easy workup procedure, large substrate tolerance, high reaction yield, good recyclability, and environmental friendliness. [ABSTRACT FROM AUTHOR]

This article provides a comprehensive report on the rhodium(III)-catalyzed C–H activation in indole from 2017 to 2022. The direct functionalization of C–H bonds offers a more sustainable and economically sensible route in organic synthesis, reducing the production of hazardous waste. Rhodium has been widely used as a catalyst for C–H functionalization due to its excellent functional group compatibility, versatility, reactivity, and selectivity. The article focuses on the utilization of Rh(III) catalyst for C–H activation of the indole moiety, which is a structurally important building block in natural products and pharmaceutical treatments. Various methods for directed C–H functionalization of indoles, such as C2 activation, alkylation, hydroarylation, and dual C–H activation reactions, are discussed. The text also discusses various methods for the synthesis of carbazole derivatives, benzo[e]indoles, and selective functionalization of indoles through C–H activation. While progress has been made in this area, there are still challenges to overcome, such as the need for harsh reaction conditions and stoichiometric metal oxidants. Continued research in this field is expected to improve reaction conditions and increase overall efficiency. [Extracted from the article]

[Beta]-hairpin structures have been crystallographically characterized only in very short acyclic peptides, in contrast to helices. The structure of the designed [Beta]-hairpin, t-butoxycarbonyl-Leu-Val-Val-D-Pro-Gly-Leu-Val-Val-OMe in crystals is described. The two independent molecules of the octapeptide fold into almost ideal [Beta]-hairpin conformations with the central D-Pro-Gly segment adopting a Type II[prime] [Beta]-turn conformation. The definitive characterization of a [Beta]-hairpin has implications for de novo peptide and protein design, particularly for the development of three- and four-stranded [Beta]-sheets.

Sulfonated reduced graphene oxide (SrGO) has displayed great potential as a solid acid catalyst due to its efficiency, cost-effectiveness, and reliability. In this study, SrGO was synthesized by the introduction of sulfonic acid-containing aryl radicals onto chemically reduced graphene oxide using ultrasonication. The SrGO catalyst was characterized by Fourier Transform Infrared (FTIR) spectroscopy, Raman spectroscopy, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and transmission electron microscopy (TEM). Further, SrGO was effectively utilized as a metal-free and reusable solid acid catalyst for the chemoselective N - t -Boc protection of various aromatic and aliphatic amines under solvent-free conditions. The N - t -Boc protection of amines was easily achieved under ambient conditions affording high yields (84–95%) in very short reaction times (5 min–2 h). The authenticity of the approach was confirmed by a crystal structure. The catalyst could be easily recovered and was reused up to seven consecutive catalytic cycles without any substantial loss in its activity. [ABSTRACT FROM AUTHOR]

Tetrazoles are synthetic organic heterocyclic compounds comprising of high nitrogen content among stable heterocycles. Tetrazoles, chiefly 5-substituted 1 H -tetrazoles have been used as a bioisosteric replacement for carboxylic acids in medicinal chemistry. Various clinical drugs, including losartan, cefazolin, and alfentanil, contain the tetrazole moiety. There have been significant developments in the synthesis of 5-substituted 1 H -tetrazoles. Researchers are still working to develop more efficient and ecofriendly methods for their synthesis. In this review, we provide a comprehensive discussion of the recent advancements in the field of synthesis of 5-substituted 1 H -tetrazoles. 1 Introduction 2 The Role of 5-Substituted 1 H -Tetrazoles in Medicinal Chemistry 3 Synthesis of 5-Substituted 1 H -Tetrazoles 3.1 Microwave-Assisted Synthesis 3.2 Heterogeneous Catalysts 3.3 Nanoparticles as Heterogeneous Catalysts 3.4 Miscellaneous Methods 4 Sartans: A Class of Tetrazole-Based Commercial Drugs 5 Conclusions [ABSTRACT FROM AUTHOR]