Chemistry of Heterocyclic Compounds最新文献

A simple one-step protocol for the synthesis of 3-amino-1-benzothiophene-2-carbonitriles from commercially or synthetically readily available S-(cyanomethyl) O-ethyl carbodithionate and 2-fluorobenzonitriles was developed.

Exercise plays an important role in regulating energy homeostasis, which affects the diversity of the intestinal microbial community in humans and animals. To the best of the authors' knowledge, few studies have reported the associations between horse gut microbiota along with their predicted metabolic activities and the athletic ability of Jeju horses and Thoroughbreds living in Korea. This study was conducted to investigate the association between the gut microbiota and athletic performance in horses. This study sequenced the V3 and V4 hypervariable regions of the partial 16S rRNA genes obtained from racehorse fecal samples and compared the fecal microbiota between high- and low-performance Jeju horses and Thoroughbreds. Forty-nine fecal samples were divided into four groups: high-performance Jeju horses (HJ, n = 13), low-performance Jeju horses (LJ, n = 17), high-performance Thoroughbreds (HT, n = 9), and low-performance Thoroughbreds (LT, n = 10). The high-performance horse groups had a higher diversity of the bacterial community than the low-performance horse groups. Two common functional metabolic activities of the hindgut microbiota (i.e., tryptophan and succinate syntheses) were observed between the low-performance horse groups, indicating dysbiosis of gut microbiota and fatigue from exercise. On the other hand, high-performance horse groups showed enriched production of polyamines, butyrate, and vitamin K. The racing performance may be associated with the composition of the intestinal microbiota of Jeju horses and Thoroughbreds in Korea.

This microreview provides a comprehensive analysis of synthetic approaches to chromeno[2,3-c]pyrrol-9(2H)-ones, a promising class of compounds that incorporate chromene and pyrrole frameworks. Starting from their earliest mentions and encompassing the latest advancements, this review categorizes the synthetic methods based on the structure of the starting materials.

The reaction of diethyl ethynyl- and 2-phenylethynylphosphonates with pyridinium methylides generated in situ from phenacyl- and 2-ethoxy-2-oxoethylpyridinium salts by the action of a base was studied. As a result of the reaction, the corresponding diethyl indolizin-1-ylphosphonates were formed. In this case, diethyl ethynylphosphonate demonstrated higher reactivity and underwent a reaction at room temperature in the K₂CO₃–MeCN system, while reactions with 2-phenylethynylphosphonate proceeded at elevated temperatures and resulted in lower indolizine yields.

This microreview provides an overview of the literature for the past six years (2018–2023) on the synthesis of cyclic sulfonates (put simply, sultones) highlighting the most efficient methods and utilization of conceptually novel approaches and unprecedented reactions.

Conjugation of glycosyl isothiocyanates and steroidal amino alcohol derived from estrone, followed by an oxidative cyclodesulfuration reaction allowed the synthesis of a new class of bioactive molecules. This rapid and versatile protocol represents a useful approach toward the synthesis of a wide variety of novel 2-aminobenzoxazoles. The glycoconjugates (mono- and disaccharides) were successfully obtained in good to excellent yields. The acetyl-protected and deprotected compounds were screened for antiproliferative activity against six human cancer cell lines; a total of eight compounds showed mild to moderate activity. Remarkably, both derivatives bearing a mannose moiety exhibited GI₅₀ values at the low μM range.

A novel four-component diastereoselective synthesis of piperidin-2-one salts containing a quaternized pyridine unit is reported. The Michael–Mannich cascade was conducted using Michael acceptors, pyridinium ylides, aromatic aldehydes, and ammonium acetate in methanol. It is a convenient approach to the synthesis of 1-((3SR,4RS,6SR)-4,6-diaryl-5,5-dicyano-2-oxopiperidin-3-yl)pyridin-1-ium halides with three stereocenters in 48–84% yield or 1-[(3SR,4RS,5RS,6SR)-4,6-diaryl-5-cyano-5-(methoxycarbonyl)-2-oxopiperidin-3-yl]-pyridin-1-ium halides with four stereocenters in 44–74%. This reaction is highly stereoselective. Only one diastereomer was formed. Ammonium acetate plays a dual role, acting as a base and as a nitrogen source. Structures of the synthesized compounds were confirmed by ¹H, ¹³C NMR, IR, and mass spectra. The formation of a single diastereomer was confirmed by singe crystal X-ray diffraction studies. Products were obtained by simple filtration, and other purification methods as column chromatography were not necessary.

C(sp²)H functionalization of pyrrole, indole, indolyl-3-acetic acid (heteroauxin), and 2-amino-3-(indol-3yl)propionic acid (tryptophan) was carried out via a one-pot C-thiomethylation with formaldehyde and mercaptans in pyridine which simultaneously played the role of a catalyst and solvent. The possibility of the synthesis of structurally diverse sulfanyl methylindoles depending on the nature of the reagents was demonstrated.

Ring-chain isomerism of aldehyde semicarbazones/1,2,4-triazolidin-3-ones was first studied in detail. Aliphatic aldehyde semicarbazones completely cyclized under the action of very strong Brønsted acids (TfOH, HCl) in aprotic solvents at room temperature to give the corresponding salts of the N1-protonated 1,2,4-triazolidin-3-ones. Both the obtained salts and their free bases are unstable in the presence of air oxygen and undergo slow oxidative aromatization. A novel synthesis of 2-alkyl-2,4-dihydro-3H-1,2,4-triazol-3-ones via the TfOH-promoted cyclization of aliphatic aldehyde semicarbazones followed by aromatization of the isolated crude 1,2,4-triazolidin-3-ones or their hydrotriflates with m-CPBA was developed. In contrast to aliphatic aldehyde semicarbazones, the cyclization of benzaldehyde semicarbazones does not proceed in the presence of strong Brønsted acids. Thermodynamic and kinetic characteristics of the aldehyde semicarbazone ring-chain isomerism are discussed based on the DFT B3LYP/6-311++G(d,p) calculations.

In this microreview, the application of [3+2] cycloaddition reactions for the selective preparation of nitroisoxazoles and their hydrogenated analogs was analyzed on the basis of recent publications. It was found that most discussed processes are realized at room temperature with high or full selectivity.