On the conformational characteristics of the O,O,O-trimethyl selenophosphate molecule

Spectroscopic and theoretical studies were carried out for O,O,O-trimethyl selenophosphate molecule. DFT structural and vibrational calculations were performed at 6-311++G^∗∗ level. Ar/matrix-FTIR spectra were recorded. A coexistence of different conformers with C₃ and C₁ symmetries was detected at different temperatures. Spectral evidence of a lower energy C_s conformer was found. These conclusions are consistent with the results from DFT calculations. A tentative assignment of the features observed in the Ar/matrix-FTIR spectra is proposed.     

A Review on the Main Phytoconstituents,Traditional Uses,Inventions, and Patent Literature of Gum Arabic Emphasizing Acacia seyal

Acacia seyal is an important source of gum Arabic. The availability, traditional, medicinal, pharmaceutical, nutritional, and cosmetic applications of gum acacia have pronounced its high economic value and attracted global attention. In addition to summarizing the inventions/patents applications related to gum A. seyal, the present review highlights recent updates regarding its phytoconstituents. Traditional, cosmetic, pharmaceutical, and medicinal uses with the possible mechanism of actions have been also reviewed. The patent search revealed the identification of 30 patents/patent applications of A. seyal. The first patent related to A. seyal was published in 1892, which was related to its use in the prophylaxis/treatment of kidney and bladder affections. The use of A. seyal to treat cancer and osteoporosis has also been patented. Some inventions provided compositions and formulations containing A. seyal or its ingredients for pharmaceutical and medical applications. The inventions related to agricultural applications, food industry, cosmetics, quality control of gum Arabic, and isolation of some chemical constituents (L-rhamnose and arabinose) from A. seyal have also been summarized. The identification of only 30 patents/patent applications from 1892 to 15 November 2021 indicates a steadily growing interest and encourages developing more inventions related to A. seyal. The authors recommend exploring these opportunities for the benefit of society.     

Secondary Metabolites,including a New 5,6-Dihydropyran-2-One,Produced by the Fungus Diplodia corticola. Aphicidal Activity of the Main Metabolite,Sphaeropsidin A

An undescribed 5,6-dihydropyran-2-one, namely diplopyrone C, was isolated and characterized from the cultures of an isolate of the fungus Diplodia corticola recovered from Quercus suber in Algeria. The structure and relative stereostructure of (5S,6S,7Z,9S,10S)-5-hydroxy-6-(2-(3-methyloxiran-2-yl)vinyl)-5,6-dihydro-2H-pyran-2-one were assigned essentially based on NMR and MS data. Furthermore, ten known compounds were isolated and identified in the same cultures. The most abundant product, the tetracyclic pimarane diterpene sphaeropsidin A, was tested for insecticidal effects against the model sucking aphid, Acyrthosiphon pisum. Results showed a toxic dose-dependent oral activity of sphaeropsidin A, with an LC₅₀ of 9.64 mM.     

Chemically induced dynamic nuclear polarizations (CIDNP) and kinetic studies of the decomposition of di-t-butylmagnesium, -zinc,and -mercury

Pulsed Fourier transform NMR was used to study ¹H-CIDNP arising from the thermolysis of di-t-butylmagnesium 1 and -zinc 2 and from the thermolysis and photolysis of di-t-butylmercury 3 in deuterated hydrocarbons as solvents. The decomposition of 1, 2, and 3 leads to metal, to the polarized disproportionation products isobutane 4 and isobutene 5 (rate constant k_d), and to the unpolarized combination product 2,2,3,3-tetramethylbutane 6 (rate constant k_c). Analysis of the ratio k_d/k_c as well as the activation entropies for the decomposition establish a radical mechanism for the main process. In the decomposition of 1 and 2 an A/E multiplet polarization of 4 and 5 is observed. This is opposite to the E/A polarization of these products arising during the thermolysis of 3. The photolysis of 3, however, leads to an A/E polarization of 4 and 5. The different phases of the multiplets indicate a decomposition of dialkylmercury in a cage reaction. Dialkylmagnesium and -zinc, however, decompose in a free-radical reaction of uncorrelated t-butyl pairs.     

A new,simple, one-pot route for the synthesis of azocine derivatives

A novel, simple, one-pot procedure for the synthesis of new 7H-naphtho[1,8-ef]pyrimido[4,5-b]azocine-7,10,12,13(8H,9H,11H)-tetraones by the addition reaction of acenaphthoquinone and 6-aminouracil derivatives followed by oxidative cleavage of the corresponding intermediate product in the presence of lead(IV) acetate is reported. Clean reactions, excellent yields, and mild conditions are the main features of this method. The structural assignments are supported by ¹H NMR, ¹³C NMR, and X-ray crystallography data.     

General procedure for the synthesis of ortho-vinylbenzyl-substituted amines, ethers, and sulfides

A convenient procedure has been proposed for the synthesis ortho-vinylbenzyl-substituted ethers, amines, and sulfides via reaction of o-(2-bromoethyl)benzyl bromide with various nucleophiles.     

Agariblazeispirols A and B, an unprecedented skeleton from the cultured mycelia of the fungus, Agaricus blazei

Agariblazeispirols A and B, which have a unique steroidal skeleton, have been isolated from the cultured mycelia of Agaricus blazei (Agaricaceae). The absolute structure of Agariblazeispirol A was established to be (20S,22R,23R,24S)-13β,22:22,25-diepoxy-5-methoxy-14β-methyl-18-nor-des-A-ergosta-5,7,9,11-tetraen-23-ol by extensive 1D and 2D NMR spectral data, and X-ray analysis. The structure of Agariblazeispirol B was elucidated to be a stereoisomer of agariblazeispirol A at its carbon 22, (20S,22S,23R,24S)-13β,22:22,25-diepoxy-5-methoxy-14β-methyl-18-nor-des-A-ergosta-5,7,9,11-tetraen-23-ol by comparison of extensive 1D and 2D NMR spectral data with those of agariblazeispirol A. Both compounds showed a moderate circumvention of drug resistance on mouse leukemia P388/VCR cells.     

Isolation, synthesis, and neurite outgrowth-promoting activity of illicinin A from the flowers of Illicium anisatum

Two new prenylated C₆-C₃ compounds, illicinin A (1) and (4S)-illicinone I (2), were isolated from the flowers of Illicium anisatum. The structures of the new compounds were elucidated by spectroscopic methods. The absolute structure of (4S)-illicinone I was determined by comparing its CD spectrum and specific rotation with those of (4S)-illicinone A (4). Illicinin A (1) and 4-allyl-2,6-dimethoxy-3-(3-methylbut-2-enyl)phenol (3) were found to exhibit neurite outgrowth-promoting activity at concentrations ranging from 0.1 to 10 μM in primary cultured rat cortical neurons. Illicinin A and its derivatives were synthesized for structure-activity relationship studies by employing sequential Stille reactions to introduce a prenyl and an allyl group to the benzene ring, thereby indicating that an allylphenyl moiety in the molecule of 1 is essential for its neurotrophic properties.     

Mild, powerful, and robust methods for esterification, amide formation, and thioesterification between acid chlorides and alcohols, amines, thiols, respectively

We developed two efficient practical methods for esterification, amide formation, and thioesterification between acid chlorides and alcohols, amines, thiols, respectively. The present mild and robust reaction was performed by two separate methods both by combining cheap and readily available amines, N-methylimidazole, and N,N,N′,N′-tetramethylethylenediamine (TMEDA). Method A uses catalytic N-methylimidazole and TMEDA with an equimolar amount of K₂CO₃, whereas Method B uses equimolar amounts of N-methylimidazole and TMEDA. The salient features are as follows. (i) With regard to reactivity, Method B was superior to Method A for esterification and thioesterification, whereas cost-effective Method A was superior to Method B for amide formation. (ii) Amide formation proceeded smoothly between acid chlorides and less nucleophilic and stereocongested amines such as 2,6-dichloroaniline. (iii) This protocol was applied to the successful synthesis of two agrochemicals, bromobutide and carpropamid.     

The Isolation and Characterization of Antagonist Trichoderma spp. from the Soil of Abha,Saudi Arabia

Background: The genus Trichoderma is widely spread in the environment, mainly in soils. Trichoderma are filamentous fungi and are used in a wide range of fields to manage plant patho-genic fungi. They have proven to be effective biocontrol agents due to their high reproducibility, adaptability, efficient nutrient mobilization, ability to colonize the rhizosphere, significant inhibitory effects against phytopathogenic fungi, and efficacy in promoting plant growth. In the present study, the antagonist Trichoderma isolates were characterized from the soil of Abha region, Saudi Arabia. Methodology: Soil samples were collected from six locations of Abha, Saudi Arabia to isolate Trichoderma having the antagonistic potential against plant pathogenic fungi. The soil dilution plate method was used to isolate Trichoderma (Trichoderma Specific Medium (TSM)). Isolated Trichoderma were evaluated for their antagonistic potential against Fusarium oxysporum, Alternaria alternata and Helminthosporium rostratum. The antagonist activity was assessed by dual culture assay, and the effect of volatile metabolites and culture filtrate of Trichoderma. In addition, the effect of different temperature and salt concentrations on the growth of Trichoderma isolates were also evaluated. Results: The most potent Trichoderma species were identified by using ITS4 and ITS 5 primers. Total 48 Trichoderma isolates were isolated on (TSM) from the soil samples out of those six isolates were found to have antagonist potential against the tested plant pathogenic fungi. In general, Trichoderma strains A (1) 2.1 T, A (3) 3.1 T and A (6) 2.2 T were found to be highly effective in reducing the growth of tested plant pathogenic fungi. Trichoderma A (1) 2.1 T was highly effective against F. oxysporum (82%), whereas Trichoderma A (6) 2.2 T prevented the maximal growth of H. rostratum (77%) according to the dual culture data. Furthermore, Trichoderma A (1) 2.1 T volatile metabolites hindered F. oxysporum growth. The volatile metabolite of Trichoderma A (6) 2.2 T, on the other hand, had the strongest activity against A. alternata (45%). The Trichoderma A (1) 2.1 T culture filtrate was proven to be effective in suppressing the growth of H. rostratum (47%). The temperature range of 26 °C to 30 °C was observed to be optimum for Trichoderma growth. Trichoderma isolates grew well at salt concentrations (NaCl) of 2%, and with the increasing salt concentration the growth of isolates decreased. The molecular analysis of potent fungi by ITS4 and ITS5 primers confirmed that the Trichoderma isolates A (1) 2.1 T, A (3) 3.1 and A (6) 2.2 T were T. harzianum, T. brevicompactum, and T. velutinum, respectively. Conclusions: The study concludes that the soil of the Abha region contains a large population of diverse fungi including Trichoderma, which can be explored further to be used as biocontrol agents.     

A chiron approach to (1R,2R,5S,7S)-2-hydroxy-exo-brevicomin: a component of the volatiles produced by the male mountain pine beetle,Dendroctonus ponderosae

A chiron approach for the synthesis of (1R,2R,5S,7S)-2-hydroxy-exo-brevicomin 1, a component of the volatiles obtained from male mountain pine beetles, Dendroctonus ponderosae has been achieved. Our synthesis started with commercially available d-ribose and involves a Wittig olefination, an acid catalyzed one pot hydrogenation and the internal acetalization as key steps.     

A graphic model for calculating the properties of alkylsilanes, based on the additivity of energy contributions

A 18-constant additive scheme for calculating the physicochemical properties of alkylsilanes is obtained, based on the transferability of subgraphs in molecular graphs of the homologic SiC _n H_{2n + 4} series of alkylsilanes. The model considers multiple nonvalence interactions through no more than one atom and pair nonvalence interactions through no more than three skeletal atoms along a molecular chain. A linear dependence is established within the classification of the structural elements in a molecule. The enthalpies of formation Δ_f H° (g, 298 K) for alkylsilanes SiC _n H_{2n + 4} not studied experimentally were calculated numerically by considering different approximations.     

New nonstoichiometric molybdate,tungstate, and vanadate catalysts with the scheelite-type structure

Phases of the formula A_1?xфxMO₄ with the scheelite-type structure are described where ф represents a vacancy at the A cation site and M is Mo⁶⁺, W⁶⁺, and/or V⁵⁺. Many different univalent, divalent, and trivalent A cations were used in this study. The phases with no defects, i.e., x = 0, were known except for those of the type A¹⁺_.5A³⁺_.5MO₄ where A¹⁺ is Ag or Tl and M is Mo⁶⁺ or W⁶⁺. Phases with x > 0 are generally new and were prepared for catalytic studies. An excellent correlation between catalytic properties and defect concentration has been observed.     

Effect of plasma on the scattering of electrons with helium-like ions: C V,N VI,and O VII

A distorted wave (DW) approach is used to study the effect of plasma on the electron impact excitation of helium-like ions: C V, N VI, and O VII. The Debye-Huckel model for plasma screening is used. Collision strengths for the 1¹ S–2¹ P transition are presented for two values of screening length (ΛZ=10 and ΛZ=20).     

Pimprinols A–C,from the terrestrial actinomycete,Streptomyces sp.

A Streptomyces sp. Lv3-13, isolated from the rhizosphere soil of the plant Mespilus germanica, has yielded three new pimprinine derivatives, named pimprinols A–C (1–3) and the unknown (2-aminophenyl)(2-ethyloxazol-5-yl) methanone (4) along with the known compounds 2-ethyl oxazole pimprinine and 2-propyl oxazole pimprinine. The structures of the compounds were elucidated based on spectroscopic methods including UV, HR-ESIMS and 1D, 2D NMR data. Compounds 1–4 were screened for antimicrobial and cytotoxic activities.     

Concentration,temperature, and isotopy effects on the heat capacity of aqueous urea

Relations for the apparent molar heat capacity ?_c of urea in an aqueous solution depending on the molality m and temperature were obtained. A transition to the relations ?_c(m,T) for D₂O-(ND₂)₂CO and T₂O-(NT₂)₂CO systems was effected by temperature scaling. At low temperatures, the isotherms of the molar heat capacity C _p(m) of the protium and deuterium systems have minima shifted to more dilute solutions at elevated temperatures. At m = 1, C _p of a solution does not depend on temperature in both systems. The dependences C _p(T) also have minima at constant concentrations. The temperature of the minimum heat capacity is most effectively lowered by small additions of urea. For m = 0.25, T _min is 7.5 K lower than T _min of pure water, and its heat capacity is 0.08 J/(mol K) higher. A transition from m = 1.5 to m = 2 lowers the temperature of the minimum heat capacity by 3.6 K; thus, the heat capacity of solutions differs by 0.02 J/(mol K) only.     

Chemical transformations of diazoles in the reactions of carboxylation, N-siloxycarbonylation, and transsilylation

The behavior of 3,5-dimethylpyrazole, 3(5)-methylpyrazole, imidazole and their trimethyl-silyl derivatives in carboxylation, N-siloxycarbonylation, and transsilylation reactions was studied. A new Nsiloxycarbonylation reagent, diazole trimethylsilyl derivative-carbon dioxide, was found. This reagent makes it possible to obtain easily O-silylurethanes starting from primary, secondary amines and hydrazine derivatives, as well as to develop a convenient one pot synthesis method for trimethylsiloxycarbonyldiazoles.     

Agariblazeispirol C from the cultured mycelia of the fungus, Agaricus blazei, and the chemical conversion of blazeispirol A

Agariblazeispirol C, which has a unique steroidal skeleton, has been isolated from the cultured mycelia of Agaricus blazei (Agaricaceae). The structure of agariblazeispirol C was established to be (23S,24S)-13,23-cyclo-25-hydroxy-14β-methyl-18-nor-des-A-ergosta-5,7,9,11,17(20)-pentaen-22-one by comparison of extensive 1D and 2D NMR spectral data with those of agariblazeispirols A and B. At the same time, agariblazeispirol C was synthesized by the reaction of blazeispirol A with BF₃·OEt₂ along with some interesting compounds.     

Theoretical study on the structures,force field,and vibrational spectra of cyclooctatetraene and cyclooctatetraene-d8

The structures and force field of 1,3,5,7-cyclooctatetraene (COT) have been studied using ab initio theory at the SCF level with the 4-21G basis set. The quadratic force field of the D_2d structure obtained by systematic scaling of the ab initio force constants successfully reproduces the observed frequencies of COT and COT-d₈ with a mean deviation of less than 10 cm⁻¹ for non-CH stretching modes. On the basis of the calculated results, assignments of the fundamental vibrations are examined. The normal mode υ₅ is reassigned to a weak band at 758 cm⁻¹ in the Raman spectrum of COT and to a weak band at 591 cm⁻¹ in the Raman spectrum of COT-d₈. The calculations favor the assignment of υ₂₆ given by Lippincott et al. [J. Am. Chem. Soc. 73, 3370 (1951)] over the revised assignment of Perec [Spectrochim. Acta 47A, 799 (1991)]. The calculations also furnish reliable prediction for the inactive A₂ fundamentals of COT and COT-d₈. The fundamental frequencies and IR and Raman intensities of ¹³CC₇H₈, which constitutes about 9% of COT in natural abundance, are also calculated. Only ν₁₀ (calculated at 908 cm⁻¹) of the formal inactive A₂ modes has appreciable Raman intensity (0.23 Å⁴/amu). A spectral feature due to this fundametal is identified in the liquid Raman spectrum of Tabacik and Blaise [C. R. Acad. Sci. Ser. II 303, 539 (1986)] as a weak peak at 908 cm⁻¹.     

Antifungal Activity of Soft Tissue Extract from the Garden Snail Helix aspersa (Gastropoda,Mollusca)

Gastropods comprise approximately 80% of molluscans, of which land snails are used variably as food and traditional medicines due to their high protein content. Moreover, different components from land snails exhibit antimicrobial activities. In this study, we evaluated the antifungal activity of soft tissue extracts from Helix aspersa against Candida albicans, Aspergillus flavus, and Aspergillus brasiliensis by identifying extract components using liquid chromatography-tandem mass spectrometry (LC-MS-MS). Two concentrations of three extracts (methanol, acetone, and acetic acid) showed antifungal activity. Both acetone (1 g/3 mL) and acetic acid extracts (1 g/mL) significantly inhibited C. albicans growth (p = 0.0001, 5.2 ± 0.2 mm and p = 0.02, 69.7 ± 0.6 mm, respectively). A. flavus and A. brasiliensis growth were inhibited by all extracts at 1 g/mL, while inhibition was observed for acetic acid extracts against A. brasiliensis (p = 0.02, 50.3 ± 3.5 mm). The highest growth inhibition was observed for A. flavus using acetic acid and acetone extracts (inhibition zones = 38 ± 1.7 mm and 3.1 ± 0.7 mm, respectively). LC-MS-MS studies on methanol and acetone extracts identified 11-α-acetoxyprogesterone with a parent mass of 372.50800 m/z and 287.43500 m/z for luteolin. Methanol extracts contained hesperidin with a parent mass of 611.25400 m/z, whereas linoleic acid and genistein (parent mass = 280.4 and 271.48900 m/z, respectively) were the main metabolites.