8-Methyl-3-methylsulfanyl-8a,8b-dihydro-5H-1-oxa-2,4-diazaacenaphthylene

In the tricyclic title compound, C11H12N2OS, the 2,3,4,5-tetrahydropyridine ring adopts a half-chair conformation. This ring makes dihedral angles of 27.72 (7) and 45.17 (7)°, respectively, with the isoxazole and the cyclohexa-1,3-diene rings while the isoxazole ring is oriented at an acute angle of 63.46 (7)° with respect to the cyclohexa-1,3-diene ring. In the crystal, molecules associate via C—H...N hydrogen bonds and C—H...π interactions, forming a three-dimensional network.

5-Nitroisoxazoles in SNAr Reactions: Access to Polysubstituted Isoxazole Derivatives

An efficient protocol for straightforward functionalization of isoxazole ring via the reactions of aromatic nucleophilic substitution of nitro group with various nucleophiles has been elaborated. The method is featured with...

Synthesis of 3-arylisoxazoles and their sulfamide derivatives

Great interest in binuclear aromatic systems containing an isoxazole ring and a sulfamide group is due to the effect of two pharmacophore groups at once on the biological activity of these compounds. This article is devoted to the development of a method for the synthesis of 3-arylisoxazole-containing compounds and their sulfamide derivatives from simple and accessible products of organic synthesis. The target products of the developed multistage schemes are derivatives of various bicyclic systems containing an isoxazole ring and a second aromatic ring associated with a sulfofragment. The synthesis of 3-aryl-5-acylaminoisoxazoles was carried out by sequential conversion of methyl esters of aromatic carboxylic acids into the corresponding nitriles by reaction with acetonitrile in the presence of sodium hydride in dioxane. At the next stage, the nitriles reacted with hydroxylamine in an aqueous solution of sodium hydroxide to form the corresponding bicyclic amines, which were then acylated in acetonitrile with acetic acid chloride in the presence of pyridine. The total yields of 3-aryl-5-N-acylaminoisoxazoles were at least 60%. It was found that the sulfonylchlorination of 3-aryl-5-N-acylamino derivatives of isoxazole, depending on the experimental conditions and the structure of the starting substrates, forms both mono- and disulfochlorides. The regioselectivity of the sulfochlorination reaction of the synthesized bicyclic systems was proved by 1H NMR spectroscopy. The influence of various factors on the course of the sulfochlorination reaction of the synthesized bicyclic systems was studied. The dependence of the direction of the electrophilic attack on the structure of the compounds and on the conditions of the experiment was established. As a result of the performed research, both mono and disulfochlorination products were obtained. With an increase in the reaction time, the disulfonylchlorination product accumulates and the deacylation reaction proceeds in parallel. Convincing proof of the structure of all synthesized compounds has been carried out using a complex of modern methods of physical and chemical analysis.

Antimicrobial, Antioxidant, and Anticancer Activities of Some Novel Isoxazole Ring Containing Chalcone and Dihydropyrazole Derivatives

Our previous work identified isoxazole-based chalcones and their dihydropyrazole derivatives as two important five-membered heterocycles having antitubercular activity. Hence, in the present study, we biologically evaluated 30 compounds, including 15 isoxazole ring-containing chalcones (17–31) and 15 dihydropyrazoles (32–46) derived from these chalcones for their antimicrobial, antioxidant, and anticancer activities. Chalcones exhibited superior antibacterial and antioxidant activities compared to dihydropyrazoles. Among the chalcones, compound 28 showed potent antibacterial (MIC = 1 µg/mL) and antioxidant activities (IC50 = 5 ± 1 µg/mL). Dihydropyrazoles, on the contrary, demonstrated remarkable antifungal and anticancer activities. Compound 46 (IC50 = 2 ± 1 µg/mL) showed excellent antifungal activity whereas two other dihydropyrazoles 45 (IC50 = 2 ± 1 µg/mL) and 39 (IC50 = 4 ± 1 µg/mL) exhibited potential anticancer activity. The compounds were also tested for their toxicity on normal human cell lines (LO2) and were found to be nontoxic. The active compounds that have emerged out of this study are potential lead molecules for the development of novel drugs against infectious diseases, oxidative stress, and cancer.

A computational study of the chemical reactivity of isoxaflutole herbicide and its active metabolite using global and local descriptors

In this work, the chemical reactivity of isoxaflutole (ISOX) and diketonitrile (DKN) was analyzed at the X/6-311++G(2d,2p) (where X = = B3LYP, M06, M06L and ?B97XD) level of theory, in the gas and aqueous phases. The results indicate that DKN, the active metabolite of ISOX, is more stable than isoxaflutole in both phases. ISOX is susceptible to electrophilic and free radical reactions through the isoxazole ring; while the carbonyl group is attacked by nucleophiles. For DKN nucleophilic and free radical attacks are expected on the aromatic ring, while electrophilic attacks are favored on the oxygen atom of the carbonyl groups. The results suggest that the cleavage of the N?O bond in the isoxazole ring is possible through electrophilic and free radical attacks, while electrophilic and free radical attacks will favor substitutions on the carbonyl groups of DKN.

9α-Hydroxy-4,8-dimethyl-3′-phenyl-3,14-dioxatricyclo[9.3.0.02,4]tetradec-7-en-13-one-12-spiro-5′-isoxazole monohydrate

In the title compound, C22H25NO5·H2O, the ten-membered ring displays an approximate chair–chair conformation, whereas the five-membered furan ring has an envelope conformation, with the C atom of the methine group adjacent to the spiro C atom as the flap. The isoxazole ring is almost planar and its plane is slightly inclined to the plane of the attached phenyl ring. The mean plane of the furan ring is nearly perpendicular to that of the isoxazole ring, as indicated by the dihedral angle between them of 89.39 (12)°. In the crystal, the organic molecules are linked into [010] chains by O—H...O hydrogen bonds. The water molecule forms O—H...O and O—H...N hydrogen bonds and a weak C—H...O interaction is also observed. Together, these lead to a three-dimensional network.

2-Methyl-3′-(4-methylphenyl)-4′-(2-nitrophenyl)-4′H-spiro[chroman-3,5′-isoxazol]-4-one

The title compound, C25H20N2O5, crystallizes with two molecules (A and B) in the asymmetric unit with similar conformations. The five-membered rings are both in envelope conformations with the spiro C atom as the flap. The six-membered heterocycles display half-chair conformations. The mean plane through the isoxazole ring is nearly perpendicular to those through the spiro-chroman system and the 4-nitrophenyl moieties, as indicated by the dihedral angles of 81.42 (9) and 87.58 (8)°, respectively, between them in molecule A. Equivalent data for molecule B are 75.58 (9) and 84.15 (8)°, respectively. The p-tolyl plane makes a dihedral angles of 24.10 (9) and 28.78 (8)° with the isoxazole ring in molecules A and B, respectively. In the crystal, molecules are linked by C—H...O and C—H...N hydrogen bonds and C—H...π interaction, forming a three-dimensional network.