Chemistry of Heterocyclic Compounds最新文献

A regioselective and trans-diastereoselective method for the preparation of 2-aryl-2,3-dihydro-1H-benzo[f]chromenes based on 2-naphthol Mannich bases as precursors of 1,2-naphthoquinone 1-methides and highly polarized β-(N,N-dimethylamino)styrene was developed. The resulting cycloadducts were transformed into cyclic acetals and hemiacetals as well as introduced into the Cope reaction leading to 2-aryl-1H-benzo[f]chromenes.

The carbodiimide-mediated coupling of 4-cyanonicotinic acid with L-amino acid methyl esters takes place with the predominant formation of bicyclic compounds – methyl 2-(1-imino-3-oxo-1,3-dihydro-2H-pyrrolo[3,4-c]pyridin-2-yl)alkanoates, which are monoimino derivatives of 4-azaphthalimide. Under the action of hydroxylamine they undergo pyrrolidine cycle opening with the formation of pseudopeptides – coupling products of nicotinic acid with amino acid esters bearing an amidoxime function at position 4.

Alkylaromatic 1-hydroxyamino-2-oximes reacted at the hydroxyamino group with glyoxylic acid hydrate, providing 4-aryl(hetaryl)-1-hydroxy-2,5-dihydro-1H-imidazole-2-carboxylic acid 3-oxides that were converted upon heating into 5-aryl(hetaryl)-1-hydroxy-1H-imidazoles containing a hydrogen atom at the heterocycle position 2.

A simple procedure for the synthesis of N-substituted 2-amino-1,4,5,6-tetrahydropyrimidines from isocyanates with a wide variety of substituents was developed.

Today, the chemistry of quaternary ammonium compounds is rapidly developing field owing, among other things, to the need to combat periodic outbreaks of various infectious diseases, which in some cases assume pandemic proportions. This review summarizes the most recent studies, published mainly over the past 10 years, devoted to advances in the synthesis of bisquaternary ammonium compounds for various purposes. The synthetic methods include monoalkyl halogenation of diamines, dialkyl halogenation of amines, methyltrifluoromethanesulfonation reactions, and anion exchange reactions.

This microreview is dedicated to new and modified existing methods for the formation of the 1,3-oxazolidin-2-one ring. The material covers key studies published since 2021.

A novel access to pyrrolo[3,4-d]pyrimidine scaffold via tandem Staudinger/intramolecular aza-Wittig reaction of 5-acyl-4-(1-azidoalkyl)-3,4-dihydropyrimidin-2(1H)-ones promoted by PPh₃ was developed. Synthesis of the starting pyrimidinones involved the reaction of readily available N-[(2-azido-1-tosyl)alkyl]ureas with Na enolates of benzoylacetone or acetylacetone followed by acid-catalyzed dehydration of the resulting products without their isolation.

Regio- and stereoselective cleavage of derived camphor α-diketones bearing functional group at the bridgehead position under Bucherer–Bergs reaction conditions was studied for a range of model compounds that are easily accessible from naturally occurring feedstock. In all cases, cleavage of the carbon–carbon bond between the carbonyl groups led to the formation of functionalized hydantoins containing cyclopentane moiety in their structures. Products were obtained in high yields with no purification required, warranting the use of this methodology for the development of libraries of biorelevant compounds.

The data on multicomponent methods of tetrahydro-4H-indol-4-one synthesis published over the past ten years are summarized in this review. Three main synthetic approaches in the construction of such molecules are considered. Among them are: condensation of cyclohexane-1,3-diones with α-halogenoketones and primary amines, three-component reaction of cyclic enaminoketones, arylglyoxals, and methylene active compounds, and condensation of cyclic enaminoketones and arylglyoxals in the presence of nucleophilic reagents (often solvents). The latter domino reaction runs under microwave irradiation and leads to the functionalization of position 7 of the indole ring system. The material is systematized according to the structure of the starting compounds.

The reactions of nitrosoalkenes, generated in situ from the corresponding α-bromooxime upon the action of a base, with electron-rich olefins were used to synthesize a series of heterocyclic compounds containing 1,2-oxazines, the expected Diels–Alder cycloadducts. The structural features of the obtained heterocyclic compounds were determined based on NMR spectra, HRMS, and X-ray structural analysis.