NiFe2 O4 as a magnetically recoverable nanocatalyst for odourless C-S bond formation via the cleavage of C-O bond in the presence of S8 under mild and green conditions

One-pot synthesis of 11-sulfenyl dibenzodiazepines via tandem sulfenylation/cyclization of o-isocyanodiaryl amines and diaryl disulfides

A one-pot sulfenylation/cyclization of o-isocyanodiaryl amines has been described for the preparation of 11-sulfenyl dibenzodiazepines. This AgI-catalyzed reaction covers an unexplored tandem process to give seven-membered N-heterocycles. This transformation shows a broad range of substrate scope, simple operation, and moderate to good yields under aerobic conditions. Diphenyl diselenide can also be produced in an acceptable yield.

Metal-free photo-induced sulfidation of aryl iodide and other chalcogenation

A photo-induced C-S radical cross-coupling of aryl iodides and disulfides under transition-metal and external photosensitizer free conditions for the synthesis of aryl sulfides at room temperature has been presented, which features mild reaction conditions, broad substrate scope, high efficiency, and good functional group compatibility. The developed methodology could be readily applied to forge C-S bond in the field of pharmaceutical and material science.

Recyclable magnetically retrievable nanocatalysts for C–heteroatom bond formation reactions

During recent years, magnetic separation has proven to be a highly indispensable and sustainable tool for facile separation of catalysts from the reaction medium with the aid of only an external magnetic force that precludes the requirement of energy intensive, solvent based centrifugation or filtration techniques. Extensive research in the area of catalysis has clearly divulged that while designing any catalyst, the foremost features that need to be paid due attention to include high activity, ready recoverability and good reusability. Fortunately, the magnetic nanocatalysts involving a superparamagnetic core material that could comprise of iron oxides such as magnetite, maghemite or hematite or mixed ferrites (CoFe2O4, CuFe2O4) have offered bright prospects of designing the ideal catalysts by proving their efficacy as strong support material that could be further engineered with various tools of nanotechnology and efficiently catalyze various C–heterobond formation reactions. This chapter provides succinct overview of all the approaches utilized for fabricating different types of magnetic nanoparticles and strategies adopted for imparting them durability. The prime forte however remains to exclusively showcase the applications of the various types of magnetic nanocatalysts in C–O, C–N, C–S and miscellaneous (C–Se, C–Te) bond formation reactions which are anticipated to benefit the synthetic community on a broad spectrum by helping them rationalize and analyze the key features that need to be taken into account, while developing these magical nanostructured catalytic systems for boosting the green bond formation reactions/transformations.

Magnetic mesocellular foams with nickel complexes: as efficient and reusable nanocatalysts for the synthesis of symmetrical and asymmetrical diaryl chalcogenides

In this work, magnetic mesocellular foam (M-MCF) silica nanoparticles were prepared via inserting magnetic nanoparticles into the pores of mesocellular foams, the inner surface of which was functionalized with a methionine-nickel complex (M-MCF@Met-Ni). The structure of the as-prepared nanocatalysts was studied by FT-IR spectroscopy, BET, TGA, VSM, SEM, HR-TEM, EDS, WDX, XRD, and ICP-OES techniques. Thereafter, this nanocatalyst was used as a new, effective, and magnetically reusable catalyst for C-S and C-Se bond formation under mild conditions. All corresponding products were prepared with good yields and appropriate turnover number (TON) and turnover frequency (TOF), which reveals the high activity of this magnetic nanocatalyst in both reactions. In addition, the recovery and hot filtration tests indicated that this catalyst could be simply separated from the reaction mixture using an outside magnet and reused five consecutive times without any significant loss of its catalyst activity or metal leaching.

Supported Cu(II)-Schiff base: novel heterogeneous catalyst with extremely high activity for eco-friendly, one-pot and multi-component C-S bond-forming reaction toward a wide range of thioethers as biologically active cores

An effective and proficient process for the synthesis of a variety of thioethers via the one-step reaction of benzyl halides, aryl halides, and thiourea is presented. This strategy is a one-pot procedure to achieve a variety of thioethers without the requirement to thiols as starting compounds. A range of thioethers containing electron donating/electron-withdrawing functional groups were obtained with good to excellent yields under mild conditions. Moreover, the nanocatalyst exhibited excellent recyclability for the reaction, making it more sustainable. One-pot and multi-component synthesis, high yields of final products, green reaction media, high activity of nanocatalyst, simple separation of the products and catalyst, and high regioselectivity are several highlights of this method.

NiFe2O4 nanoparticles: an efficient and reusable catalyst for the selective oxidation of benzyl alcohol to benzaldehyde under mild conditions

Benzaldehyde is one of the most important and versatile organic chemicals for industrial applications. This study explores a milder approach for the fabrication of NiFe₂O₄ nanoparticles (NPs) for use as a catalyst in the selective oxidation of benzyl alcohol to benzaldehyde. A co-precipitation method coupled with hydrothermal aging has been adopted to synthesize NiFe₂O₄ NPs in the absence of any additive. Different techniques such as electron microscopy, diffractometry, and photoelectron spectroscopy have been used to characterize the products. The results showed that the synthesized NiFe₂O₄ NPs are spherical, pure, and highly crystalline with sizes below 12 nm possessing superparamagnetic behaviour. The catalytic activity of the synthesized NiFe₂O₄ NPs has been assessed in the selective oxidation of benzyl alcohol under ambient reaction conditions. A conversion of 85% benzyl alcohol with 100% selectivity has been attained with t-butyl hydroperoxide at 60 °C in 3 h. With the optimized reaction conditions, the generality of the newly developed protocol has been expanded to a wide array of substituted benzyl alcohols with good performance. The NiFe₂O₄ nanocatalysts are magnetically separable and are reusable up to five cycles without loss of catalytic activity.

Recent Advances in the Synthesis of Sulfides, Sulfoxides and Sulfones via C-S Bond Construction from Non-Halide Substrates

The construction of a C-S bond is a powerful strategy for the synthesis of sulfur containing compounds including sulfides, sulfoxides, and sulfones. Recent methodological developments have revealed lots of novel protocols for C-S bond formation, providing easy access to sulfur containing compounds. Unlike traditional Ullmann typed C-S coupling reaction, the recently developed reactions frequently use non-halide compounds, such as diazo compounds and simple arenes/alkanes instead of aryl halides as substrates. On the other hand, novel C-S coupling reaction pathways involving thiyl radicals have emerged as an important strategy to construct C-S bonds. In this review, we focus on the recent advances on the synthesis of sulfides, sulfoxides, and sulfones from non-halide substrates involving C-S bond construction.

l-Methionine–Pd complex supported on hercynite as a highly efficient and reusable nanocatalyst for C–C cross-coupling reactions

An l-methionine–Pd complex was covalently immobilized on the surface of hercynite (FeAl₂O₄) MNPs, and its catalytic properties were studied in C–C coupling reactions.