Letters in Organic Chemistry - Volume 20, Issue 11, 2023

A newly designed heterogeneous copper catalytic platform immobilizing copper (II) salt on chitosan Schiff base-modified carbon nanotubes was developed (Cu@CS-Py@CNT). The structure of the catalyst platform was fully characterized by spectroscopic analyses. The catalytic activity of the Cu@CS-Py@CNT was investigated in a one-pot synthesis of 1,4-disubstituted 1,2,3-triazoles by the regioselective click reaction using various benzyl halides or their surrogates, terminal alkynes, and sodium azide in an aqueous environment without using any external Cu-reducing agents.

Irritant, expensive, or toxic desulfurating agents are usually used in the synthesis of isothiocyanates from amines, CS2, and appropriate bases, accompanied by a tedious workup. A more practical and green method has been developed. Cheap and non-toxic CaO was used as both a base and a desulfurating agent in the synthesis of isothiocyanates. Both alkyl and aryl isothiocyanates are easily synthesized in moderate to high yield from amines, CS2, and CaO under mild conditions. A simple and practical synthetic approach for isothiocyanates from amines, CS2, and CaO was developed. CaO acts as both a base and a desulfurating agent in the reactions, simplifying the reaction system and reducing cost as well as side products. Moderate to high yields were obtained at room temperature in 48 hours which included alkyl and aryl isothiocyanates.

Marine-derived macrolides that occur naturally exhibit a range of biological properties, including antibacterial and antifungal activity. Sharpless epoxidation and intramolecular acylation via the Friedel-Crafts method for the macrolide ring formation was used as the main steps in the regioselective construction of naturally existing xestodecalactone C, which was started from chiral propylene oxide. The isolated yellow coloured final product had a 91% yield, and FT-IR, Mass, ¹H-NMR, and ¹³C NMR were used to characterise each product. As a result, chiral propylene oxide was used as the starting material for the regioselective total synthesis of the naturally occurring xestrodecalactone C, with the main stages being intramolecular Friedel-Crafts acylation for macrolide ring formation and Sharpless epoxidation. The synthesis of numerous xestrodecalactone C analogues relevant for bioevaluation can be done quickly and easily using this synthetic approach.

In the past few years, scientists have learned more about how the human body uses Damino acids and how their synthesis occurs. This has rekindled interest in researching them. D-amino acids are known to be important in an extensive variety of physiologic operations taking place inside the human body. The correlation between these radicals and the physiology of human beings is that Daspartate and D-serine affect nerve signalling. Along with these, several other D-amino acids have also been linked to adjusting acquired immunity and the outcome of the gut barrier. Importantly, several conditions, including psychosis and amyotrophic lateral sclerosis, as well as age-related conditions, including cataracts and atherosclerosis, have been linked to the existence of D-amino acids within the human body. Also, there is more and more evidence that radicals interpret a role in the cause, progression, and treatment of cancer. This article will review the many approaches to synthesizing D-amino acids and their impact on the environment, animals, and the human body. In addition, scientific information addressing the methods of cytostatic action of D-amino acids as well as their prospective applications in industry and medicine, is included in this article.

Based on various research reports, pyridine possesses a wide range of pharmacological activities along with many other industrial applications. Because of its diverse applications, pyridine moiety is the center of attraction for researchers, and many patents have been granted focusing on it. Several synthetic protocols, such as cyclo-condensation, cyclization, cycloaddition, electrolysis, etc., were used by researchers to synthesize pyridine and analogs. Each synthetic protocol has merits and demerits and requires several types of reagents, catalysts, and reaction conditions. So, there is always a need for careful analysis of reported synthetic protocols whenever researchers like to initiate research on synthesizing pyridine and its analogs. The therapeutic activity of successfully marketed drugs might be possible because of the presence of pyridine in their structure. Any small alteration in the structure of the medicinal compounds may produce a major change in their pharmacological action. So, the correlation between the structure of its analogs with biological activity is also important. The proposed article also includes recently reported pharmacological activities and the structureactivity relationship of pyridine and its analogs. This article aims to help the researchers by highlighting recently reported methods for synthesizing pharmacologically useful pyridine analogs and their merits.

Following the success of the first intermolecular cyclopropanations of diazo acetoxy acetone with olefins using a novel p-nitro-Ru(II)-diphenyl-Pheox catalyst, other α-functionalized diazoketones have synthesized using the same reaction conditions. Consequently, chiral cyclopropyl products were formed with excellent yield (up to 87% yield), high diastereoselectivity (up to 99:1), and high enantioselectivity (up to 90% ee).

In this study, synthesis of ferrocenylimidazo[1,2-a]pyridine-3-amines was reported from the condensation reaction of ferrocenecarboxaldehyde, 2-aminopyridine, and isocyanides using ZrO(NO3)2.2H2O as an efficient, new, and reusable catalyst under reflux conditions in ethanol. The structures of the products were confirmed by IR, ¹H NMR, ¹³C NMR, and elemental analysis. Quantum theoretical calculations for the structure of compounds (4a, 4b, and 4c) were done using the Def2 with the TZVPPD basis set. Geometric parameters were obtained from the optimized structures, and experimental results were analyzed with the calculated data. The structures of the products were proved by IR, ¹H NMR, ¹³C NMR, and elemental analysis. Computations were carried out for the IR spectra data and ¹H NMR and ¹³C NMR chemical shifts of the ferrocenylimidazo[1,2-a]pyridine-3- amine derivatives in the ground state. Ultimately, a great agreement was found between experimental and theoretical results.

In the current study, a simple and reliable technique for the synthesis of 2,5-disubstituted 1,3,4-thiadiazoles from ethylbenzimidate and benzothiohydrazides were devised. This protocol goes via a base-mediated nucleophilic addition elimination process, followed by intramolecular rearrangement. Our method utilizes commonly accessible and non-toxic substrates and a simple workup procedure to produce high to exceptional yields (70-91%) of 2,5-diphenyl 1,3,4-thiadiazoles derivatives with a wide range of substitutions. We present a simple procedure for the synthesis of 1, 3, 4- thiadiazole using ethylbenzimidate and benzothiohydrazides in the presence of Et3N in DMSO solvent as affordable and easily accessible starting materials to create derivatives under ambient conditions.

In this study, a continuous flow reactor was used to synthesize Ru nanoparticles with a well-distributed size and good stability. The effects of reactant dilution and flow rate on the synthesis were investigated, and it was found that optimization of these parameters was critical in obtaining small-sized Ru nanoparticles using a solution of 0.00025 M RuCl3.3H2O and 0.001M NaBH4 at a flow rate of 30mL/h. The Ru nanoparticles obtained were coated with CTAB surfactant, which was confirmed by TEM and PSD studies. The interaction between the surfactant and the nanoparticles was also confirmed by FTIR analysis. The synthesized Ru nanoparticles were then tested for their catalytic activity in high-pressure alkene hydrogenation and were found to be effective in producing the corresponding hydrogenated products in good yields. Furthermore, the catalytic effect of Ru nanoparticles was utilized for the synthesis of two natural products, brittonin A and dehydrobrittonin A. Both products were successfully isolated in measurable yields. This synthesis protocol had several advantages, including low catalyst loading, no use of additives, wide substrate scope, simple product separation, and catalyst recovery up to 8 times. Overall, this study demonstrated the potential of continuous flow reactor technology for synthesizing stable and well-distributed nanoparticles, and the effectiveness of Ru nanoparticles as catalysts in various chemical reactions. The study's findings have important implications for the development of more efficient and sustainable chemical synthesis protocols.

The conventional mixed acid nitration of aromatic hydrocarbons has been extensively applied in the industry, but usually, it is not highly selective and may cause environmental concerns regarding the disposal of large volumes of mixed acids. This paper proposes a new method of orientational para-nitration of easily hydrolyzable aromatic compounds. Under the optimized reaction conditions, the easily hydrolyzed aromatic compounds were nitrated in the H2SO4-HNO3-H3PO4 system to yield paste-like products. And the product could be directly filtered out from the mixed acid, avoiding a large amount of waste liquid caused by pouring the reaction mixture into ice water by the traditional post-treatment method. The selectivity and yield of nitration by this method have been improved, and the mother liquor could be reused, thereby reducing the cost and pollution.