A novel application of the oxidizing properties of urea nitrate and peroxydisulfate-cobalt(II): aromatization of NAD(P)H model Hantzsch 1,4-dihydropyridines

Ammonium metavanadate (NH4VO3): a highly efficient and eco-friendly catalyst for one-pot synthesis of pyridines and 1,4-dihydropyridines

In this study, we reported the ammonium metavanadate (NH₄VO₃) as an efficient, cost-effective, and mild catalyst for the synthesis of substituted pyridines via a one-pot pseudo four-component reaction. Furthermore, we investigated Hantzsch 1,4-dihydropyridines (1,4-DHPs) synthesis and oxidation of 1,4-DHPs to their corresponding pyridines. The present approach offers a rapid methodology for accessing various pyridines with broad functional group tolerance and good yields using NH₄VO₃ catalyst as a green catalyst.

A Facile Aromatisation of 1,4-dihydropyridines by Ammonium Nitrate in Acetic Acid

The oxidation of 1,4-dihydropyridines to pyridines with ammonium nitrate as an oxidant in the presence of acetic acid proceeds in excellent yield.

Urea nitrate catalyzed synthesis of 2-arylbenzothiazoles using the grindstone technique

An efficient, green and environmentally friendly grindstone method for the synthesis of 2-arylbenzothiazole derivatives in the presence of urea nitrate as the catalyst under solvent-free conditions was developed. All products were characterized by elemental analysis and spectral methods.

Oxidative dehydrogenation of C-C and C-N bonds: A convenient approach to access diverse (dihydro)heteroaromatic compounds

Nitrogen heteroarenes form an important class of compounds which can be found in natural products, synthetic drugs, building blocks etc. Among the diverse strategies that were developed for the synthesis of nitrogen heterocycles, oxidative dehydrogenation is extremely effective. This review discusses various oxidative dehydrogenation strategies of C-C and C-N bonds to generate nitrogen heteroarenes from their corresponding heterocyclic substrates. The strategies are categorized under stoichiometric and catalytic usage of reagents that facilitate such transformations. The application of these strategies in the synthesis of nitrogen heteroarene natural products and synthetic drug intermediates are also discussed. We hope this review will arouse sufficient interest among the scientific community to further advance the application of oxidative dehydrogenation in the synthesis of nitrogen heteroarenes.

Iodobenzene diacetate (IBD) catalyzed an quick oxidative aromatization of Hantzsch-1,4-dihydropyridines to pyridines under ultrasonic irradiation

This project was undertaken to demonstrate the potential of iodobenzene diacetate for the oxidative aromatization of Hantzch-1,4-dihydropyridines under ultrasonic irradiation. All reactions were carried out under ultrasonic irradiation and results were compared with traditional method. Sonochemical switching was observed in case of oxidative aromatization of 4-n-alkyl substituted 1,4-DHP. Without sonication, dealkylation occurred in case of n-alkyl substituted 1,4-DHP (ionic mechanism) but under ultrasonic irradiation, n-alkyl group was not expelled (radical mechanism). However, secondary alkyl (isopropyl) and benzyl group were expelled under both conditions.

Diversity-oriented synthesis of benzimidazole, benzoxazole, benzothiazole and quinazolin-4(3H)-one libraries via potassium persulfate-CuSO4-mediated oxidative coupling reactions of aldehydes in aqueous micelles

Libraries of 2-substituted-benzimidazoles, benzoxazoles, benzothiazoles as well as quinazolin-4(3H)-ones were synthesized via potassium persulfate-CuSO(4)-mediated oxidative coupling of aldehydes with o-phenylenediamines, o-aminophenols, o-aminothiophenols, and anthranilamide, respectively, in aqueous micelles. The strategy opens a way for rapid generation of libraries of small heterocycles for biological screening. The reagent is commercially available, cheap, and highly chemoselective. The yields were superior in aqueous micelles to those in organic solvents. Short reaction times, large-scale synthesis, excellent chemoselectivity, excellent yields, as well as environmental friendliness are the main advantages of this diversity-oriented synthesis.

Oxidative aromatization of 1,4-dihydropyridines and pyrazolines using HbA-H(2)O(2): An efficient biomimetic catalyst system providing metabolites of drug candidates

Human hemoglobin (HbA) efficiently catalyses the oxidative aromatization of 1,4-dihydropyridines (1,4-DHPs) and pyrazolines with hydrogen peroxide in phosphate buffer. The results of the study reveal that the rates of oxidative aromatization of 1,4-DHPs are substituent dependent. Thus, the present study is very useful in understanding the metabolism of 1,4-DHP drugs in liver by cytochrome P450 and designing novel drugs as well as modifying the existing drugs for better pharmacokinetic profile.