Asian Journal of Organic Chemistry最新文献

1,4-Diyn-3-ones and 1,4-diyn-3-ols have garnered considerable attention due to their distinctive characteristics, including multiple reaction sites. Numerous new reactions involving these compounds have been discovered in the past decades. Their transformations can provide a variety of useful O-containing and N-containing heterocycles with high regio- and stereoselectivity, including pyrones, pyrrolones, furans, and pyridones. In this review, we summarize the latest trends and developments of reactions involving 1,4-diyn-3-ones and 1,4-diyn-3-ols with a series of reagents including amines, water, N-oxides, 1,3-dicarbonyl compounds, quinolines, isoxazoles, and so on. We highlight the product diversity, selectivity, and applicability of these transformations and, where possible, discuss the underlying mechanistic rationale.

In the present article, a novel, efficient synthesis of structurally diverse 1,8-naphthyridin-2-ones (5a-v) from ylideneketonitriles is reported in good to decent yield, that is, 47%–60%. The two-step sequential addition method begins with ylideneketonitriles (R¹ = –CF₃, –CHF₂) reacting with primary amines (R² = –Bn, –CH₂Py, –CyPr) in acetonitrile at 80°C for 1 h, forming 2-aminopyridine derivatives (3a-f). Subsequent cyclization using acid chloride or ester with potassium carbonate in acetonitrile at 80°C for 2 h yields the target compounds. Acid chloride-mediated cyclization provides 15%–20% higher yields compared to ester. Notably, in a one-pot two-step synthesis, the yields were 10%–30% lower than the sequential two-step approach. Additionally, the multicomponent reaction (MCR) approach using ester in propionitrile as solvent and potassium carbonate as base affords the desired products in 19%–35% yield. This methodology allows facile introduction of various substituents at R¹, R², and R³ positions, enabling the generation of a novel 1,8-naphthyridin-2-ones library. This methodology offers several advantages, including the use of readily available reagents, moderate reaction temperatures, and relatively short reaction times.

The mechanism of Co-catalyzed intermolecular enantioselective C−H activation of arylphosphinamides and alkynes was carefully investigated through density functional theory (DFT) calculations. The study identifies several potential transition states (TSs), which are characterized by relatively low energy barriers and exhibit favorable reaction processes in the presence of Co(OAc)₃. Computational results suggest that the 1:1 catalyst-to-ligand ratio is preferred over the 1:2 ratio. Additionally, distortion–interaction analysis of the key TS structures indicates that the regioselectivity of the products was mainly induced by favorable interactions.

A crucial aspect of the antibacterial activity of N-phenyl pyrazolines is the presence of specific substituents in their structures. Besides, several important elements require further investigation. In this study, we synthesized a series of N-phenyl pyrazoline derivatives bearing electron-donating group substituents derived from vanillin and electron-withdrawing groups obtained from halogens. These compounds were evaluated against both Gram-positive and Gram-negative bacteria using in vitro and computational studies. The in vitro study revealed that N-phenyl pyrazoline containing the electron-donating groups (hydroxy [–OH] and methoxy [–OCH₃]) exhibited strong antibacterial activity against Gram-negative bacteria, including Escherichia coli and Shigella flexneri, as well as moderate activity against Gram-positive bacteria, such as Staphylococcus aureus and Bacillus subtilis. Furthermore, the results of the computational study supported these findings. It demonstrated that the electron-donating groups (–OH and –OCH₃) were capable of forming molecular interactions similar to those of tetracycline with several key amino acids in the DNA gyrase (GyrB receptor), including Glu50, Asp73, and Arg76, which are essential for bacterial survival. However, the presence of the electron-withdrawing groups (bromo [–Br] and chloro [–Cl]), in conjunction with the electron-donating groups, decreased antibacterial activity against all tested bacteria, resulting in moderate to weak activity.

The first study of the NBS/ceric (IV) ammonium nitrate (CAN) has emerged as a powerful and efficient reagent for the difunctionalization at C-2,2′-oxidation and C-3,3′-bromination of 3,3′-bis-7-azaindolyl methane to form isolable diastereomers of polybrominated 7-aza-bis-2-indalones as established by ¹H NMR study. The scope of the reaction, characterization of products including XRD technique, and a plausible mechanism for the formation of products are described. Synthetic use of one of the products thus obtained, namely 3′-methylene bis (3,5-dibromo-1-methyl-1,3-dihydro-2H-pyrrolo[2,3-b]pyridin-2-one), has been demonstrated by the synthesis of a functionally diverse dispiro[pyrrolo[2,3-b]pyridine-3,1′-cycloheptane derivative by a sequence of reactions (1) zinc/AcOH reduction, (2) allylation, and (3) RCM reaction using Grubbs-II catalyst.