K₂S₂O₈-Promoted Aryl Thioamides Synthesis from Aryl Aldehydes Using Thiourea as the Sulfur Source

Towards More Practical Methods for the Chemical Synthesis of Thioamides Using Sulfuration Agents: A Decade Update

Compounds possessing a thioamide function play a crucial role in organic synthesis, serving as key building blocks. They are also important in the pharmaceutical chemistry and drug design, owing to their ability to mimic the amide function in biomolecules while retaining or developing biological activity. From the synthetic viewpoint, several methods have been developed for preparing thioamides using sulfuration agents. The purpose of this review is to give an update of the last decade of contributions focusing on the formation of thioamides employing different sulfur sources. When appropriate, the cleanness and practicality of the new methods are highlighted.

Synthesis of 5-Trifluoromethyl-Substituted (Z)-N,N-Dimethyl-N′-(pyrazin-2-yl)formimidamides from 2-Aminopyrazines, LiI/Selectfluor, FSO2CF2CO2Me and DMF under Cu Catalysis

The synthesis of 5-trifluoromethyl-substituted (Z)-N,N-dimethyl-N′-(pyrazin-2-yl)formimidamides via the iodination of 2-aminopyrazines with Selectfluor/LiI followed by a domino trifluoromethylation with FSO2CF2CO2Me and a condensation with DMF in the presence of CuI is realized under mild conditions. This three-step method offers CF3-substituted (Z)-N,N-dimethyl-N′-(pyrazin-2-yl)formimidamides in yields of 55–70% and with high regioselectivities. LiI serves as an iodine source, whilst DMF functions as both a solvent and a condensation reagent. The regioselectivity of these trifluoromethylation reactions is strongly dependent upon the substituent pattern on the 2-aminopyrazines. A possible mechanism for this method is also discussed.

Water Mediated Direct Thioamidation of Aldehydes at Room Temperature

A mild, greener approach toward thioamide synthesis has been developed. Its unique features include water-mediated reaction with no input energy, additives, or catalysts as well. The presented protocol is attractive with readily available starting materials and the use of different array amines, along with a scaled-up method. Biologically active molecules such as thionicotinamide and thioisonicotinamide can be synthesized from this procedure.

Cellulose-reinforced poly(ethylene-co-vinyl acetate)-supported Ag nanoparticles with excellent catalytic properties: synthesis of thioamides using the Willgerodt–Kindler reaction

Cellulose, a bio-derived polymer, is widely used in food packaging, dye removal, coatings, and solid-supported catalysis. Heterogeneous catalysts play a critical role in environmental remediation. In this context, the demand for green and cost-effective catalysts has rapidly increased. In this study, cellulose was extracted from rice straw, and a highly active solid-supported catalytic model was developed. First, cellulose was conjugated with poly(ethylene-co-vinyl acetate) (PEVA), and then Ag nanoparticles (AgNPs) were inserted into the cellulose–PEVA composite. The process involved the reduction of AgNPs in the presence of sodium borohydride. The fabricated hybrid catalyst was characterized using Fourier-transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray, and powder X-ray diffraction. Thereafter, the obtained hybrid was used as a catalyst for the Willgerodt–Kindler reaction of aromatic aldehydes, amines, and S₈ to synthesize thioamides with excellent yields. The developed catalytic system exhibited high stability and recyclability. Moreover, the mechanical properties of the hybrid catalyst were evaluated using tensile strength and impact tests. RGB analysis of digital images was also performed to investigate the primary components of the catalyst.

The AgNPs@cellulose–PEVA hybrid catalyst presented excellent catalytic efficacy for the Willgerodt–Kindler reaction, facilitating the selective formation of C Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> S bonds.

The recent advances in K2S2O8-mediated cyclization/coupling reactions via an oxidative transformation

Recently the K₂S₂O₈ mediated cyclization/coupling reactions to construct carbon–carbon/carbon–heteroatom bond via oxidative transformation is became much interesting in organic synthesis.