1,2,3-Triazole framework: a strategic structure for C-H⋯X hydrogen bonding and practical design of an effective Pd-catalyst for carbonylation and carbon-carbon bond formation

1,2,3-Triazole is an interesting N-heterocyclic framework which can act as both a hydrogen bond donor and metal chelator. In the present study, C-H hydrogen bonding of the 1,2,3-triazole ring was surveyed theoretically and the results showed a good agreement with the experimental observations. The click-modified magnetic nanocatalyst Pd@click-Fe₃O₄/chitosan was successfully prepared, in which the triazole moiety plays a dual role as both a strong linker and an excellent ligand and immobilizes the palladium species in the catalyst matrix. This nanostructure was well characterized and found to be an efficient catalyst for the CO gas-free formylation of aryl halides using formic acid (HCOOH) as the most convenient, inexpensive and environmentally friendly CO source. Here, the aryl halides are selectively converted to the corresponding aromatic aldehydes under mild reaction conditions and low Pd loading. The activity of this catalyst was also excellent in the Suzuki cross-coupling reaction of various aryl halides with phenylboronic acids in EtOH/H₂O (1 : 1) at room temperature. In addition, this catalyst was stable in the reaction media and could be magnetically separated and recovered several times.

Algae-mediated route to biogenic cuprous oxide nanoparticles and spindle-like CaCO3: a comparative study, facile synthesis, and biological properties

Biocompatible syntheses of Cu2O nanoparticles are relatively low compared to some other reported metal oxides due to their low stability and requiring more carefully controlled synthetic conditions. In the present study, the efficiency of three brown algae (Cystoseira myrica, Sargassum latifolium and Padina australis) extracts collected from the Persian Gulf was evaluated in the biosynthesis of Cu2O nanoparticles. A fast and simplified synthesis of Cu2O nanoparticles with average size between 12 and 26 nm was successfully achieved through an eco-friendly method using the aqueous extracts of Sargassum latifolium and Cystoseira myrica. Whereas, under the same reaction conditions using Padina australis extract no Cu2O nanoparticles were produced, and unexpectedly, the results approved the formation of spindle shaped CaCO3 with average sizes of 1-2 μm in length and 300-500 nm in width. Structure, morphology and composition of the as-prepared products were characterized by XRD, FT-IR, UV-vis, TEM and FESEM analysis. This work confirms that the biomolecules present in algae have the ability to affect particle size, morphology, composition, and physicochemical properties of the synthesized particles. The Cu2O nanoparticles prepared in this study were stable and exhibited efficient antibacterial and anticancer activity. This biosynthesis technique can be valuable in environmental, biotechnological, pharmaceutical and medical applications.

One-pot synthesis of new alkyl 1-naphthoates bearing quinoline, pyranone and cyclohexenone moieties via metal-free sequential addition/oxidation reactions

A mild and one-pot synthetic pathway was successfully developed for the synthesis of new naphthoate-based scaffolds containing quinoline, pyranone and cyclohexenone moieties via a multistep reaction between acenaphthoquinone and various 1,3-diketones in the presence of different primary aliphatic and benzylic alcohols. This reaction proceeds via a sequential addition/oxidation mechanistic process including a metal-free addition step of acenaphthoquinone and 1,3-diketones followed by the H₅IO₆-mediated C–C oxidative cleavage of the corresponding vicinal diols at room temperature. The alcohols play a dual role, as the reaction solvent as well as the nucleophile, to conduct the reaction process toward naphthoate formation. All alkyl naphthoate derivatives prepared in this work are new compounds and were definitively characterized using ¹H-NMR, ¹³C-NMR and HRMS analysis, while X-ray crystallography was carried out for one of the products. The synthesis of a naphthalene-based nucleus attached to heterocyclic moieties is noteworthy to follow in the near future for diverse applications in biology, medicine, metal complex design, and semiconductor and optical materials.

Various new alkyl 1-naphthoates bearing quinoline, pyranone and cyclohexenone moieties were successfully synthesized by a one-pot sequential addition/oxidation process.

DABCO-functionalized silica–copper(i) complex: a novel and recyclable heterogeneous nanocatalyst for palladium-free Sonogashira cross-coupling reactions

Nano-CuI stabilized in a functionalized-DABCO silica matrix was prepared, characterized and evaluated as a new heterogeneous nanocatalyst in copper-catalyzed Sonogashira coupling reactions.

A click strategy for the immobilization of palladium nanoparticles onto silica: efficient and recyclable catalysts for carbon–carbon bond formation under mild reaction conditions

The synthesis of silica-grafted palladium catalyst through “click” reaction of azide-functionalized silica with methylpropargylimidazolium bromide, for Heck and Suzuki–Miyaura coupling reactions.

Copper(i) catalyzed Sonogashira reactions promoted by monobenzyl nicotinium chloride, a N-donor quaternary ammonium salt

The new catalytic complex [MBNT][Cu₄Cl₅] having a synergistic effect of coordination and electrostatic interactions was found to be efficient in palladium-free copper-catalyzed Sonogashira coupling.

Proline-functionalized chitosan–palladium(ii) complex, a novel nanocatalyst for C–C bond formation in water

An environmentally friendly palladium-based catalyst supported on proline-functionalized chitosan was successfully prepared and evaluated as a heterogeneous nanocatalyst in the Suzuki cross-coupling reaction of various aryl halides with phenylboronic acid.