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An overview is given on the significance of the oxime moiety in crop protection chemistry. This review focuses on the two most important aspects of agrochemical oximes, which are the occurrence and role of oxime groups in compounds with herbicidal, fungicidal and insecticidal activity, as well as the application of oxime derivatives as intermediates in the synthesis of crop protection agents not bearing any oxime function. Especially noteworthy is the fact, that in the synthesis of agrochemicals, oximes can be cyclized to isooxazoline, isoxazole, oxadiazole, oxazine, pyrrole, isothiazole and imidazole rings. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Polysubstituted derivatives of pyrans, chromenes, and chromeno[2,3-b]pyridines incorporating a 4,5-dichloroisothiazole or 5-arylisoxazole-3-carbaldehyde fragment in the molecule were synthesized by successive and one-step three-component reactions of 4,5-dichloroisothiazole-3-carbaldehyde and 5-arylisoxazole-3-carbaldehyde with various 1,3-diketones, malononitrile or its dimer. The structure of the target products was proven by X-ray structural analysis. Notably, it was found that the planes of the azole and chromene rings in the molecules of (1,2-azol-3-yl)chromenes are almost perpendicular. Intrinsic antitumor activity and synergistic enhancement of the activity in combination with known cytostatics used in the therapy of oncological diseases were found for some of the synthesized compounds. [ABSTRACT FROM AUTHOR]

Reactive open-shell ring systems comprising C, N, O, and S atoms are crucial for the radiation-induced molecular evolution and relevant to life and interstellar regions. Herein, we targeted the dehydro radical isomers derived from five-membered heterocycles pyrazole 1, isothiazole 2, and isoxazole 3. Using electronic structure and unimolecular decomposition-based mechanistic calculations, we attempted to envisage the variables influencing the thermodynamic and kinetic stability of radical isomers 1a–1d, 2b–2d and 3b–3d. Evidence suggests that the factors including (hetero)aromaticity, the radical electron's role in delocalization (resonance), and the ring strain play a significant role. The N-centered pyrazole radical 1a was found to be entirely delocalised, which impacts its higher thermodynamic and kinetic stability. Conversely, the C-centered radicals (1b–1d, 2b–2d, and 3b–3d) show important contributions from the interaction between the radicals and lone pair electrons, evident from the NBO analysis. The mechanistic studies through unimolecular decomposition channels show the importance of ring-opening channels as the decisive factor in their kinetic stability. Preferential cleavage of X–N or C–X bonds and formation of fragmented products like acetylene, HCN, HNC, CO, CS, NHCCH radicals, SCCH radicals, OCCH radicals, HNNC radicals, SNC radicals, and ONC radicals were also characterized. [ABSTRACT FROM AUTHOR]

The reaction of sodium 2,2-dicyanoethene-1,1-bis(thiolate) with bromine (2 equiv.) in CCl4 gave 3,5-dibromoisothiazole-3-carbonitrile and 5,5′-thiobis(3-bromoisothiazole-4-carbonitrile) in 7% and 18% yields, respectively. The latter novel compound was fully characterized. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The Pd‐catalyzed dipolar cycloaddition represents a significant synthetic strategy for the construction of useful heterocyclic compounds. This study developed the dipolar [4+2] and [6+2] cycloaddition reactions of benzo[d]isothiazole 1,1‐dioxides (BDs) leading to the synthesis of BD‐fused 1,3‐oxazinane and 1,3‐oxazocane derivatives, respectively. In particular, the synthesis of BD‐fused 1,3‐oxazinanes demonstrated regio‐ and enantioselective characteristics, resulting in products with good yields, enantioselectivity and regioselectivity (if applicable). Furthermore, the [6+2] cycloaddition reaction developed in this work represented the first strategy for the synthesis of medium‐sized ring compounds based on BDs. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The Pd‐catalyzed dipolar cycloaddition represents a significant synthetic strategy for the construction of useful heterocyclic compounds. This study developed the dipolar [4+2] and [6+2] cycloaddition reactions of benzo[d]isothiazole 1,1‐dioxides (BDs) leading to the synthesis of BD‐fused 1,3‐oxazinane and 1,3‐oxazocane derivatives, respectively. In particular, the synthesis of BD‐fused 1,3‐oxazinanes demonstrated regio‐ and enantioselective characteristics, resulting in products with good yields, enantioselectivity and regioselectivity (if applicable). Furthermore, the [6+2] cycloaddition reaction developed in this work represented the first strategy for the synthesis of medium‐sized ring compounds based on BDs. [ABSTRACT FROM AUTHOR]

The structural characterization of 3,4-dichloroisothiazole-5-carboxylic acid is performed for the first time along with the preparation of the first coordination compound based on it - a mixed-ligand europium(III) complex with 3,4-dichloroisothiazole-5-carboxylic acid and 1,10-phenanthroline. The coordination compound is characterized by the elemental analysis, single crystal and powder X-ray diffraction (XRD), and IR spectroscopy. According to the single crystal XRD data, the obtained complex is a binuclear compound with the formula [Eu2L6(phen)2(H2O)2]·6H2O. Its structure corresponds to the Chinese lantern type. The isothiazole derivative exhibits both monodentate and bidentate-bridging coordinations binding europium ions. The photoluminescent properties of a polycrystalline sample of the complex are studied: the luminescence quantum yield is 23%, the excited state lifetime is 0.8 ms. [ABSTRACT FROM AUTHOR]

An acetic acid-promoted C(sp³)-H functionalization of 2-methyl quinoline, enaminoesters and elemental sulfur for the synthesis of 3,4,5-trisubstituted isothiazoles under metal-free conditions has been developed. This approach provides viable access to various 5-(quinolin-2-yl)isothiazoles in moderate to good yields with good functional group tolerance. Moreover, the success of the gram-scale reaction gives this reaction a great potential application. [ABSTRACT FROM AUTHOR]

A novel Co(OAc)2/N-hydroxyphthalimide (NHPI)-catalyzed oxidation of 3-arylmethyl sulfonyl imines to prepare 3-arylcarbonyl analogues has been realized. 3-Arylcarbonyl sulfonyl imines were comprehensively synthesized from benzyl substrates for the first time. The reactions proceeded in moderate to excellent yields. Mechanistic investigation suggests that 3-(hydroperoxy(phenyl)methyl)benzo[d]isothiazole 1,1-dioxide A is the key intermediate for the formation of products 2. [ABSTRACT FROM AUTHOR]

The reaction of sodium 2,2-dicyanoethene-1,1-bis(thiolate) with bromine (2 equiv.) in CCl4 gave 3,5-dibromoisothiazole-3-carbonitrile and 5,5′-thiobis(3-bromoisothiazole-4-carbonitrile) in 7% and 18% yields, respectively. The latter novel compound was fully characterized.

A new two-step, one-pot synthesis of benzo[f][1,2]thiazepine 1,1-dioxides was developed, which contains a visible-light mediated aza Paternò–Büchi reaction of benzo[d]isothiazole 1,1-dioxides with alkenes and a Lewis acid catalyzed ring-expansion of azetidine. In this work, the mechanism of the aza Paternò–Büchi reaction was also investigated. [ABSTRACT FROM AUTHOR]

This study presents a quantitative estimation of the B–Hb⋯π interaction of diborane with heteroarenes (pyrrole, furan, oxazole, isoxazole, thiophene, thiazole, and isothiazole) and anionic arenes (cyclopentadienyl anion and pentazolate ion). The DFT-D3 method at the B3LYP-D3/6-311++G(d,p) level of theory was exclusively used for geometry optimization and scrutinizing the stability of the complexes. The results indicated the formation of weakly stable complexes with heterocycles and pentazolate ion (ΔE < 6.0 kcal mol−1). The complex formed between diborane and the cyclopentadienyl anion is very stable (ΔE > 12.0 kcal mol−1) with dispersive interaction playing a secondary role. The stability of the complexes suggested from MP2 calculation and other DFT (ωB97X-D and M06-2X) methods is consistent with the results obtained from the DFT-D3 method. The process of complexation is enthalpy driven, except for the complex between diborane and the cyclopentadienyl ion. The spontaneity of the process is mainly governed by the entropy factor. The plot of NCI was used to visualize the non-covalent interaction regions. NBO analysis was also performed to estimate the strength of the donor-acceptor interaction. The asymmetric and symmetric stretching of the B–Hb⋯π vibrational modes and 1H NMR shift in the free diborane and that in the complexes were also analysed. [ABSTRACT FROM AUTHOR]

Zeolites are subjects of intensive research, as they have vast industrial applications. However, exact nature of catalytic active sites remains elusive. With this research, we attempt to shed light on the Brønsted acid sites in zeolite beta modification A and correlate the widely used TPD methods of their identification with the theoretically determined strongest and weakest acid sites. A diverse set of probe molecules with a wide range of acid strength of their conjugated acids is applied to determine the heats of their adsorption over protonated zeolite beta samples. The molecules studied were acetonitrile, dimethyl sulfide, dimethyl sulfoxide, isothiazole, pyridine, tetrahydrofuran, and ammonia. It was found that the heat of adsorption of the probe molecules correlated with the acid strength of acid sites only partially. Only some of the strong acid sites were able to be identified, while the weakest acid site was often identified correctly. To conclude, the widely used method of zeolites acid sites studies delivers only partially correct results, and the conclusions from such TPD studies should be treated with caution. [ABSTRACT FROM AUTHOR]

Arylmethylenebis(3-hydroxy-2-cyclohexen-1-ones) were obtained by condensation of 1,2-azole- and pyridine-substituted aromatic aldehydes of the vanillin series with 1,3-cyclohexanedione in methanol in the presence of trimethylamine. Catalytic cyclization using fibrous sulfocationite FIBAN K-1 gave corresponding 1,8-dioxooctahydroxanthenes. [ABSTRACT FROM AUTHOR]

Reactions of 3-bromo-4-phenylisothiazole-5-carboxamide and 3-bromoisothiazole-5-carboxamide with NaNO2 (4 equiv.), in TFA, at ca. 0 °C gave the carboxylic acid products in 99% and 95% yields, respectively. The two compounds were fully characterized. [ABSTRACT FROM AUTHOR]

A reaction of 3-chloroisothiazole-5-carbonitrile with 1-iodo-4-methylbenzene (2 equiv.) produced 3-chloro-4-(p-tolyl)isothiazole-5-carbonitrile in a 60% yield. The compound was fully characterized. [ABSTRACT FROM AUTHOR]

Isothiazole units exist in many natural products and pharmaceutics. Up to now, construction of isothiazole‐containing axially chiral biaryls has not been reported yet. Herein we disclose a chiral phosphoric acid catalyzed atropoenantioselective arylation of 5‐amino‐isothiazoles with methyl p‐quinone carboxylate. Various novel isothiazole‐containing axially chiral biaryls were achieved in moderate to good yields (up to 95%) with generally moderate to good enantioselectivities (up to 90% ee). In addition, the structure of one product was determined by an X‐ray crystal structural analysis and a plausible reaction mechanism was proposed. [ABSTRACT FROM AUTHOR]

Six new palladium(II) complexes derived from previously undescribed N -(pyridin-2-yl)-1,2-azol-3-carboxamides were synthesized and characterized. Complexation of ligands proceeded unusually by deprotonation of the amide group and elimination of HCl affording the palladium(II) pincer complexes [(k3-NNN)PdCl] n (n = 1, 2), which was proven by single crystal X-ray diffraction. The structure of the complexes depended on the length of the linker between the azole and pyridine fragments. The complexes were shown to be high-turnover catalysts for Suzuki reaction in Green Chemistry conditions. [Display omitted] Synthesis, characterization, and catalytic activity of palladium(II) complexes containing tridentate N -(pyridin-2-yl)-1,2-azol-3-carboxamide ligands with various length amide linkers [CONH(CH 2) n , n = 0,1,2] is reported. Complexation of previously undescribed mixed pyridin-azol-carboxamide ligands with PdCl 2 occurs unusually by deprotonation of the amide group and elimination of HCl affording the palladium(II) pincer complexes [(k3-NNN)PdCl] n (n = 1, 2), which was proven by single crystal X-ray diffraction. The first time synthesized complexes are high-turnover catalysts, as was shown during the evaluation in Suzuki reaction between aryl halides and arylboronic acids: substituted biaryls, including practically significant, were obtained with up to quantitative yields under Green Chemistry conditions. [ABSTRACT FROM AUTHOR]

Reactions of 3-bromo-4-phenylisothiazole-5-carboxamide and 3-bromoisothiazole-5-carboxamide with NaNO2 (4 equiv.), in TFA, at ca. 0 °C gave the carboxylic acid products in 99% and 95% yields, respectively. The two compounds were fully characterized.

A reaction of 3-chloroisothiazole-5-carbonitrile with 1-iodo-4-methylbenzene (2 equiv.) produced 3-chloro-4-(p-tolyl)isothiazole-5-carbonitrile in a 60% yield. The compound was fully characterized.

Reaction of methyl 3-bromo-5-cyanoisothiazole-4-carboxylate with conc. H2SO4 gave methyl 3-bromo-5-carbamoylisothiazole-4-carboxylate in 93% yield. The compound was fully characterized.

A series of N-acyl derivatives of anabasine and cytisine were prepared, to discover novel, natural product-based medicinal agents. All synthesized compounds were tested for antimicrobial, antifungal, antiviral and analgesic activity. The most pronounced antibacterial activity was shown by the compounds with isoxazole fragments, while the adamantane derivatives showed the greatest antiviral effect. It was found that the majority of anabasine derivatives showed significant analgesic activity, reducing the pain response of animals to the irritating effect of acetic acid. The presence of a high level of antimicrobial and antiviral activity in newly synthesized compounds makes it possible to consider them promising for further study of their pharmacological properties. [ABSTRACT FROM AUTHOR]

Ammonium thiocyanate-promoted simple, rapid and eco-friendly neat synthesis of isothiazoles is developed for the first time. It is noteworthy that an instantaneous valuable synthetic route of β-enaminones is also documented during the mechanistic investigation of isothiazole formation. A detailed mechanistic explanation of the isothiazole formation reaction is clearly explained by the control experiments. NBS-promoted aromatisation of isothiazole derivatives and photophysical properties of an isothiazole-pyrene hybrid molecule have been investigated. [ABSTRACT FROM AUTHOR]

An efficient method of producing quinine derivatives via reaction of acylation with 4,5-dichloroisothiazole-3-, 5-arylisoxazole-3-, adamantane- and hydrochlorides of pyridine-3- and pyridine-4-carbonyl chlorides was developed. All synthesized compounds were tested for antiviral, antimicrobial and analgesic activity. The most pronounced antibacterial activity was shown by the compounds 2e, 3b, 3c and 3e with isoxazole and pyridine fragments. It was found that most of the tested compounds showed significant analgesic activity reducing the pain response of animals to the irritating effect of acetic acid. [ABSTRACT FROM AUTHOR]

A method for the synthesis of 5-arylisoxazole- and 4,5-dichloroisothiazole-3-carboxylic acids derivatives based on 4-acetyl- and 4-benzoylpyridine has been developed. Esters and amides were prepared by acylation of (pyridin-4-yl)methanols and (pyridin-4-yl)methanamines with acid chlorides of substituted 1,2-azole-3-carboxylic acids in ether or methylene chloride in the presence of triethylamine. Quaternary ammonium salts of synthesized pyridine derivatives were also obtained. [ABSTRACT FROM AUTHOR]

Reaction of methyl 3-bromo-5-cyanoisothiazole-4-carboxylate with conc. H2SO4 gave methyl 3-bromo-5-carbamoylisothiazole-4-carboxylate in 93% yield. The compound was fully characterized. [ABSTRACT FROM AUTHOR]

A new fluorescent ribonucleoside alphabet (mthN) consisting of pyrimidine and purine analogues, all derived from methylthieno[3,4‐d]pyrimidine as the heterocyclic core, is described. Large bathochromic shifts and high microenvironmental susceptibility of their emission relative to previous alphabets derived from thieno[3,4‐d]pyrimidine (thN) and isothiazole[4,3‐d]pyrimidine (tzN) scaffolds are observed. Subjecting the purine analogues to adenosine deaminase, guanine deaminase and T7 RNA polymerase indicate that, while varying, all but one enzyme tolerate the corresponding mthN/mthNTP substrates. The robust emission quantum yields, high photophysical responsiveness and enzymatic accommodation suggest that the mthN alphabet is a biophysically viable tool and can be used to probe the tolerance of nucleoside/tide‐processing enzymes to structural perturbations of their substrates. [ABSTRACT FROM AUTHOR]

The reaction of 4,5-dichloro-1,2,3-dithiazolium chloride with 2-(phenylsulfonyl)acetonitrile (1 equiv) in the presence of pyridine (2 equiv) gave S-(3-chloro-5-cyanoisothiazol-4-yl)benzenesulfonothioate and (Z)-2-(4-chloro-5H-1,2,3-dithiazol-5-ylidene)-2-(phenylsulfonyl)acetonitrile in 19% and 23% yield, respectively. The compounds were fully characterized and the mechanistic rationale is proposed for the formation of the benzensulfonate. [ABSTRACT FROM AUTHOR]

BACKGROUND Plant elicitors are a class of plant protection agents that can stimulate plant immunity against phytopathogen without a potential resistance problem. In searching for novel plant elicitor candidates, a series of novel N‐(2‐phenyl‐3‐pyridyl) thiadiazole/isothiazole carboxamide analogs were designed and synthesized. RESULTS: In vitro bioassay showed that all new compounds exhibited weak direct fungicidal activity. However, compounds 3b, 3g, 3n and 3o showed broad spectrum of in vivo activity against four plant fungi tested. In particularly, 3g showed 80% activity against Rhizoctonia solani in a glasshouse at a concentration of 1 μg mL–1. For induction activity of tobacco against tobacco mosaic virus (TMV), compounds 3c and 3v showed 67% and 68% inhibitory activity, respectively, which were superior to the positive controls ribavirin and ningnanmycin. Compound 3g showed moderate induction activity (41%). Reverse transcription quantitative polymerase chain reaction (RT‐qPCR) analysis found that, 3g could up‐regulate expression of genes that are related to reactive oxygen species (ROS), pathogenesis‐related protein (PRP) and salicylic acid (SA) signalling. CONCLUSION: These results indicated that 3g as an elicitor candidate might act on the SA signalling pathway. According to our findings, N‐(2‐phenyl‐3‐pyridyl) thiadiazole/isothiazole carboxamide analogs might be promising lead scaffolds as a novel plant elicitor for further investigation. [ABSTRACT FROM AUTHOR]

A photocatalyzed and highly efficient trifluoromethylation of N -arylvinylsulfonamides using commercially available CF3 SO2 Cl as the trifluoromethyl radical source under blue LEDs is reported. The reaction proceeds through radical cyclization under mild conditions. An investigation of the substrate scope is performed to establish a general, synthetically useful protocol for the synthesis of novel trifluoromethylated 1,3-dihydrobenzo[ c ]isothiazole 2,2-dioxides in moderate to high yields. This method is also successfully applied for the synthesis of difluoromethylated and trifluoroethylated 1,3-dihydrobenzo[ c ]isothiazole 2,2-dioxides in good to excellent yields. [ABSTRACT FROM AUTHOR]

1,2,3‐Thiadiazoles are precursors of thioacylcarbenes and thioketenes and show various reactions with unsaturated compounds. The rhodium‐catalyzed reactions of 1,2,3‐thiadiazoles and alk‐2‐enenitriles, including alkyl, aryl, and heteroaryl acrylonitriles, have been investigated, showing chemospecific reactivity to generate 3‐vinylisothiazole derivatives via the (3+2) transannulation between the cyano group of alk‐2‐enenitriles and generated thioacylcarbenes. (Z)‐Cinnamonitriles are less active than (E)‐cinnamonitriles due to the strong coordination of the (Z)‐C=C bond and the Rh catalyst. The current reaction provides a method for the synthesis of 3‐vinylisothiazole derivatives. [ABSTRACT FROM AUTHOR]

A series of amino derivatives of 5-arylisoxazoles and 4,5-dichloroisothiazole with primary and secondary amino groups was synthesized. 3-Aminomethyl-5-arylisoxazol-3-ylmethanamines were obtained on the basis of 5-aryl-3-(chloromethyl)isoxazoles using the Gabriel phthalimide method. 5-Arylisoxazol-3-yl- and 4,5-dichloroisothiazol-3-ylallylamines were synthesized in two ways: reduction of azomethines obtained by condensation of 5-arylisoxazolyl- and 4,5-dichloroisothiazolyl-3-carbaldehydes with allylamine, and by nucleophilic substitution of the chlorine atom in 3-chloromethyl derivatives of the corresponding azoles by reaction with allylamine. Amides and sulfonamides of azolylallylamines were synthesized. Some of the compounds obtained showed antibacterial and fungicidal activity. [ABSTRACT FROM AUTHOR]

The reaction of 4,5-dichloro-1,2,3-dithiazolium chloride with 2-(phenylsulfonyl)acetonitrile (1 equiv) in the presence of pyridine (2 equiv) gave S-(3-chloro-5-cyanoisothiazol-4-yl)benzenesulfonothioate and (Z)-2-(4-chloro-5H-1,2,3-dithiazol-5-ylidene)-2-(phenylsulfonyl)acetonitrile in 19% and 23% yield, respectively. The compounds were fully characterized and the mechanistic rationale is proposed for the formation of the benzensulfonate.

The reaction of 5-arylisoxazolyl- and 4,5-dichloroisothiazolylallylamines with pyromucic acid chlorides (2-furoyl and 5-methyl-2-furoyl chlorides) was studied. The reaction proceeds via the initial acylation of the allylamine nitrogen atom and the subsequent spontaneous intramolecular Diels–Alder reaction involving the furan ring of intermediate N-furoylamides with the formation of a single diastereomer of 3a,6-epoxyisoindol-3-ones. [ABSTRACT FROM AUTHOR]

A series of N-acyl derivatives of anabasine and cytisine were prepared, to discover novel, natural product-based medicinal agents. All synthesized compounds were tested for antimicrobial, antifungal, antiviral and analgesic activity. The most pronounced antibacterial activity was shown by the compounds with isoxazole fragments, while the adamantane derivatives showed the greatest antiviral effect. It was found that the majority of anabasine derivatives showed significant analgesic activity, reducing the pain response of animals to the irritating effect of acetic acid. The presence of a high level of antimicrobial and antiviral activity in newly synthesized compounds makes it possible to consider them promising for further study of their pharmacological properties.

The saccharine nucleus has long been recognized as a significant component in medicine. A series of pseudo-saccharine amines derivatives (7a-j) were synthesized and examined for their antibacterial activity. After testing all compounds, 7b, 7f, 7g, 7i and 7j were found most effective against Escherichia coli, Streptococcus aureus and Bacillus subtilis strains. The MIC of the compound was found from 4.6 to 16.1 µM. Further, compound 7f and 7i exhibited excellent activity against E.coli and Bacillus subtilis with MIC value 4.6 and 4.7 µM respectively. The compound 7b and 7i was found active against all the three bacteria. The zone inhibition was observed at 10 µM against Escherichia coli, Staphylococcus aureus and Bacillus subtilis at 0.9, 1.8, 3.9 respectively for 7b and 1.0, 1.8 and 2.0 cm respectively for 7i. [ABSTRACT FROM AUTHOR]

The first applying SrTiO 3 semiconductor as a photocatalyst in organic synthesis and using NPh 3 as a redox catalyst in photocatalysis was reported. With SrTiO 3 as the heterogeneous photocatalyst, NPh 3 as the homogeneous redox catalyst, H-bond as the promoter, paraformaldehyde as the cheap and atom economic methylene source, various 1,2,3,9b-tetrahydrobenzo[ d ]imidazo[1,5- b ]isothiazole 5,5-dioxides can be efficiently synthesized through the visible-light-induced cascade decarboxylative coupling/annulation reaction. [Display omitted] • Commercial SrTiO 3 semiconductor was firstly used for photocatalytic organic synthesis. • NPh 3 was firstly used as a redox catalyst in semiconductor photocatalysis. • Paraformaldehyde was used as the cheap and atom economic methylene source. • SrTiO 3 exhibits excellent photocatalytic activity for at least five catalytic cycles. The first applying SrTiO 3 semiconductor as a photocatalyst in organic synthesis and using NPh 3 as a redox catalyst in photocatalysis was reported. With SrTiO 3 as the heterogeneous photocatalyst, NPh 3 as the homogeneous redox catalyst, H-bond as the promoter, paraformaldehyde as the cheap and atom economic methylene source, various 1,2,3,9b-tetrahydrobenzo[ d ]imidazo[1,5- b ]isothiazole 5,5-dioxides can be efficiently synthesized through the visible-light-induced cascade decarboxylative coupling/annulation reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Key aroma-active and off-flavor compounds were identified in peach concentrate. • Aroma properties changed from green to cooked during thermal processing. • 1-Octen-3-one contributed to "cooked" note via linolenic acid metabolism. • "Sour/rancid" was linked to isobutyric, isovaleric acids, and isothiazole. Non-volatiles offer some insight into the formation of aroma-active components in peach puree (PP), but more depth investigation is still needed. Formation pathways of key aroma-active and off-flavor components in PP during thermal concentration (PP + C) and sterilization (PP + C + S) are unclear. Therefore, GC-O-MS combined with UPLC-MS/MS was used to identify the volatile and nonvolatile components and their formation pathways. Among the 36 aroma-active compounds, the contents of γ -decalactone, hexyl acetate, leaf acetate, hexanal, and 1-hexanol (odor activity value ≥ 1) decreased by 46 %, 100 %, 100 %, 92 %, and 100 % between PP and PP + C + S, causing the weakening of "green" and "fruity" attributes. Off-flavor components including 1-octen-3-one, isobutyric acid, isothiazole, and isovaleric acid were identified during thermal processing. 1-Octen-3-one content increased by 75 % from PP to PP + C + S through linolenic acid metabolism, which contributed to "cooked"; the formation of isobutyric and isovaleric acids, isothiazole, resulted in the enhancement of "sour/rancid" via serine and leucine metabolism. [ABSTRACT FROM AUTHOR]

2-Mercapto-1,3,4-triazoles and 2-amino-1,3,4-thiadiazoles were synthesized by successive transformations of 5-arylisoxazole- and 4,5-dichloroisothiazole-3-carboxylic acids and their derivatives. The amino group of 5-(4,5-dichloroisothiazol-3-yl)-1,3,4-thiadiazol-2-amine was acylated with 5-phenylisoxazole-3-carboxylic acid chloride. Simple approaches to the preparation of previously unknown heterocyclic assemblies containing two or three azole rings with a high potential for biological activity are described. [ABSTRACT FROM AUTHOR]

Various derivatives of 5-aryl-4-imino-3-(phenylamino)-4,5-dihydroisothiazolo[3,4-d]pyrimidines (3a-f) were synthesized. The synthesis has been done through treatment of 3-amino-4-cyano-5-(phenylamino)isothiazole with various aryl isothiocyanates. The isothiazole skeleton was obtained by the reaction of malononitrile and phenyl isothiocyanate followed by chloramine treatment. Some of the synthesized dihydroisothiazolo[3,4-d]pyrimidines were tested against different cancer cell lines, including ACHN, HeLa, HL-60, MCF-7, and PC3. Malignant cells were cultured in RPMI medium and incubated with different concentrations of the mentioned compounds. Cell viability was assessed using the MTS assay. The cytotoxicities of the synthesized compounds are not significant and are probably safe for other biological use. [ABSTRACT FROM AUTHOR]

An efficient method of producing quinine derivatives via reaction of acylation with 4,5-dichloroisothiazole-3-, 5-arylisoxazole-3-, adamantane- and hydrochlorides of pyridine-3- and pyridine-4-carbonyl chlorides was developed. All synthesized compounds were tested for antiviral, antimicrobial and analgesic activity. The most pronounced antibacterial activity was shown by the compounds 2e, 3b, 3c and 3e with isoxazole and pyridine fragments. It was found that most of the tested compounds showed significant analgesic activity reducing the pain response of animals to the irritating effect of acetic acid.

A protocol was described to access diverse isothiazoles with functionalization potential via transition metal‐free three‐component annulation of alkynones, potassium ethylxanthate (EtOCS2K) and ammonium iodide (NH4I). A sequential regioselective hydroamination/thiocarbonylation/intramolecular cyclization cascade achieved the efficient formation of consecutive C−N, C−S and N−S bonds in a one‐pot process. [ABSTRACT FROM AUTHOR]

Being a close analogue of amflutizole, methyl 4‐amino‐3‐phenylisothiazole‐5‐carboxylate (C11H10N2O2S) was assumed to be capable of forming polymorphic structures. Noncentrosymmetric and centrosymmetric polymorphs have been obtained by crystallization from a series of more volatile solvents and from denser tetrachloromethane, respectively. Identical conformations of the molecule are found in both structures. The two polymorphs differ mainly in the intermolecular interactions formed by the amino group and in the type of stacking interactions between the π‐systems. The most effective method for revealing packing motifs in structures with intermolecular interactions of different types (hydrogen bonding, stacking, dispersion, etc.) is to study the pairwise interaction energies using quantum chemical calculations. Molecules form a column as the primary basic structural motif due to stacking interactions in both polymorphic structures under study. The character of a column (straight or zigzag) is determined by the orientations of the stacked molecules (in a 'head‐to‐head' or 'head‐to‐tail' manner). Columns bound by intermolecular N—H...O and N—H...N hydrogen bonds form a double column as the main structural motif in the noncentrosymmetric structure. Double columns in the noncentrosymmetric structure and columns in the centrosymmetric structure interact strongly within the ab crystallographic plane, forming a layer as a secondary basic structural motif. The noncentrosymmetric structure has a lower density and a lower (by 0.59 kJ mol−1) lattice energy, calculated using periodic calculations, compared to the centrosymmetric structure. [ABSTRACT FROM AUTHOR]

We report elastic integral and differential cross sections for electron scattering from the aza-derivatives of pyrrole, furan, and thiophene, namely, pyrazole, imidazole, isoxazole, oxazole, isothiazole, and thiazole. The calculations were performed within the Schwinger multichannel method with pseudopotentials, with inclusion of static, exchange, and polarization interactions, for energies up to 10 eV. We found two π* shape resonances and a high-lying σ* shape resonance in each system. A sharp low-energy σ* resonance was also identified in isothiazole and thiazole. Pyrazole and imidazole presented yet a broad low-lying σ* resonance. The positions of the resonances agree very well with existing experimental results. We discuss the similarities and differences among the resonances of these compounds. [ABSTRACT FROM AUTHOR]

Two new neutral ruthenium(II) complexes [Ru(η6‐p‐cymene)Cl2(1)] (3) and [Ru(η6‐p‐cymene)Cl2(2)] (4) (1=5‐(phenylamino)‐3‐pyrrolidin‐1‐ylisothiazole‐4‐carbonitrile; 2=3‐morpholin‐4‐yl‐5‐(phenylamino)isothiazole‐4‐carbonitrile) have been synthesized and characterized using elemental analysis, IR, UV‐Vis and NMR spectroscopy. The crystal structure was confirmed for complex 3 and both ligands. Examination of the interactions of ligands and complexes with CT‐DNA (Calf Thymus DNA), as well as with HSA (Human Serum Albumin) revealed that ligands and complexes could interact with CT‐DNA through intercalation and could bind strongly with HSA. Docking experiments toward DNA dodecamer indicate excellent accordance with experimental ΔG values. The cytotoxic activity of ligands and complexes was evaluated by MTT assay against HCT116 and HeLa tumoral cells. The complexes 3 and 4 showed good activity and selectivity on HCT116 cells. Neither of the tested compounds shows cytotoxic activity against a healthy MRC‐5 cell line. Flow cytometry analysis showed the apoptotic death of the HCT116 cells with a cell cycle arrest in the S‐phase. [ABSTRACT FROM AUTHOR]

The chemistry of isothiazoles is being intensively developed, which is evidenced by the wide range of selective transformations involving the isothiazole heterocycle and the high biological activity of its derivatives that can be used as effective new drugs and plant protection chemicals. Some representatives of isothiazoles have proven to be synergists of bioactive substances, which opens the way to lower the doses of drugs used and is especially important in cancer chemotherapy. In the framework of the present review, the accomplishments in the chemistry of isothiazoles over the past 18 years are examined, whilst current strategies for the synthesis of isothiazole-containing molecules and key directions of studies in this field of heterocyclic chemistry are discussed. Considerable attention is paid to chlorinated isothiazoles and strategies for their use in the synthesis of biologically active substances. In addition, a comprehensive review of existing literature in the field of metal complexes of isothiazoles is given, including the results and prospects for the practical use of isothiazole–metal complexes as catalysts for cross-coupling reactions in aqueous and aqueous–alcoholic media ('green chemistry'). 1 Introduction 2 Synthesis by Ring-Forming Reactions 2.1 Intramolecular Cyclization 2.2 (4+1)-Heterocyclization 2.3 (3+2)-Heterocyclization 2.4 Syntheses by Ring Transformations 3 Isothiazoles by Ring Functionalization Reactions: Nucleophilic Substitution, Cross-Coupling and Side-Chain Functionalization 4 Selected Syntheses of Biologically Active Isothiazole Derivatives 5 Isothiazoles in the Synthesis of Transition-Metal Complexes and in Metal-Complex Catalysis 6 Conclusion [ABSTRACT FROM AUTHOR]

Shrimps and prawns are known to generate a characteristic and pleasant aroma when cooked whole, including their shells and viscera. This study investigated this characteristic aroma of whole-roasted shrimp using Argentine red shrimp (Pleoticus muelleri). Shrimps were roasted in an oven, and the aroma changed upon the usage of whole shrimp. The aroma attributes of "roasted" and "rich" were significantly improved. We performed an analysis of volatile compounds to identify the contributors to roasted and rich aromas and identified 17 odor-active compounds. Heterocyclic compounds including pyrazines, thiazolines, and thiazoles were major contributors to the aroma of whole roasted shrimp. In aroma extract dilution analysis, 2,6-dimethylpyrazine, trimethylpyrazine, 2-ethyl-3,5-dimethylpyrazine, 2-acetyl-2-thiazoline, methional, 2-acetylthiazole, 2,5-dimethylpyrazine, 2,3-dimethylpyrazine, and indole were detected with higher flavor dilution factors than were other odor-active compounds. Furthermore, sensory evaluation analysis confirmed that pyrazines contributed to the roasted aroma, and thiazolines and thiazoles contributed to both the roasted and rich aromas. In conclusion, pyrazines, thiazolines, and thiazoles derived from shrimp shells or viscera were the major contributors to the characteristic aroma of whole roasted shrimp and strongly influenced the aroma impression of shrimp dishes. [ABSTRACT FROM AUTHOR]

C11H6Cl2N2O3S2, triclinic, P1‾ (no. 2), a = 6.974(3) Å, b = 8.132(3) Å, c = 12.349(5) Å, α = 86.123(4)°, β = 78.299(4)°, γ = 85.715(4)°, V = 682.9(4) Å3, Z = 2, Rgt(F) = 0.0410, wRref(F2) = 0.1058, T = 296(2) K. [ABSTRACT FROM AUTHOR]

C11H6Cl2N2O3S2, triclinic, P1‾ (no. 2), a = 6.974(3) Å, b = 8.132(3) Å, c = 12.349(5) Å, α = 86.123(4)°, β = 78.299(4)°, γ = 85.715(4)°, V = 682.9(4) Å3, Z = 2, Rgt(F) = 0.0410, wRref(F2) = 0.1058, T = 296(2) K. [ABSTRACT FROM AUTHOR]