Ethanolic Potassium Hydroxide Research Articles

Benzo[6,7]cyclohepta[1,2-d]pyrazolo[1,5-a]pyrimidines: Regioselective synthesis of a Novel Ring System, DFT-based NMR prediction, local reactivity indexes, and MEP analysis

Novel benzo[6,7]cyclohepta[1,2-d]pyrazolo[1,5-a]pyrimidines were prepared as a new ring system utilizing a regioselective protocol. A mixture of the appropriate 3,5-diamino-1H-pyrazoles and benzosuberone-based enones in ethanolic potassium hydroxide solution was heated at reflux for 5 h to produce the novel benzosuberone-fused pyrazolo[1,5-a]pyrimidines in 87–94 % yields. Both spectral data as well as elemental analyses were used to establish the structure of the novel products. Theoretical calculation of chemical shifts of NMR spectra is a powerful tool in analyzing experimental spectra for known substrates as well as elucidating the chemical structure for unknown ones. Using the DFT-GIAO approach under the B3LYP and mPW1PW91 functions, as well as a variety of basis sets, including 6–31G(d,p), 6–31+G(d), 6–311G(d), 6–311+G(d,p), 6–311++G-(d,p), and 6–311+G(2d,p), the chemical shifts of 1H- and 13C NMR in DMSO were calculated. The results that are most similar to the experimental observations are obtained from the computation of the chemical shift values under the 6–31G(d,p) or 6–31+G(d,p) basis sets and mPW1PW91 when using the multistranded approach. By identifying the preferred regions for electrophilic and nucleophilic attack, DFT-based FMO, global descriptors, local reactivity indexes, and MEP mapping were applied at the B3LYP function using the 6–31+G(d,p) basis set to provide additional insight into the regioselectivity in the desired reaction as well as the plausible mechanism for the formation of new products.

2-((5-(5-Methyl-2-phenyl-1H-imidazol-4-yl)-1,3,4-oxadiazol-2-yl)thio)-1-phenylethan-1-one

A promising imidazole compound was synthesized through the following route. The reaction of 5-methyl-2-phenyl-1H-imidazole-4-carbohydrazide (1) with carbon disulfide and potassium hydroxide in ethanol (80%) afforded potassium salt (2). Refluxing of (2) with phenacyl bromide (3) in ethanol/water (1:1) gave 2-((5-(5-methyl-2-phenyl-1H-imidazol-4-yl)-1,3,4-oxadiazol-2-yl)thio)-1-phenylethan-1-one (4) in a 76% yield. The structure of the title heterocycle (4) was confirmed by single-crystal X-ray diffraction and nuclear magnetic resonance.

Synthesis of New Pyrazolo[1,5‐a]pyrimidines as Potential Antibacterial Agents: In Vitro and In Silico Study

AbstractIn this study, we aimed to establish two new series of pyrazolo[1,5‐a]pyrimidines starting from 1H‐pyrazole‐3,5‐diamine. The first series was prepared by reacting 1H‐pyrazole‐3,5‐diamine with the appropriate enaminones in pyridine at 120 °C for 5–6 h to produce 7‐arylpyrazolo[1,5‐a]pyrimidines in 87–94 % yields. Furthermore, α,β‐unsaturated ketones was reacted with 1H‐pyrazole‐3,5‐diamine in ethanolic potassium hydroxide solution at 80 °C for 4 h to produce a second series of regioisomeric 5,7‐diarylpyrazolo[1,5‐a]pyrimidines in 88–96 % yields. The antibacterial activity of new products was tested against six different bacterial strains. Substituting para‐arene units at C5 and/or C7 on the pyrazolo[1,5‐a]pyrimidine structure improved efficacy, with electron‐releasing substituents having the greatest impact. Some new pyrazolo[1,5‐a]pyrimidine were found to be more effective than ciprofloxacin, with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values up to 2.2 and 4.4 μM, respectively. These compounds were deemed to have drug‐like properties according to SwissADME and drug‐likeness model scores.

Synthesis, biological activities, molecular docking, theoretical calculations of some 1,3,4-oxadiazoles, 1,2,4-triazoles, and 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazines derivatives

In this elucidation, we synthesized different 1,3,4-oxadiazoles, 1,2,4-triazoles, and 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazine ring system through the reaction of hydrazide derivatives with CS2 in ethanolic potassium hydroxide, then acidification of it with HCl to afford the corresponding oxadiazole ring, also with NH2NH2 gave the corresponding aminothioxotriazole moiety which they act as building blocks for the formation of different heterocycles when they react with phenacyl bromide to afford the corresponding 1,3,4-oxadiazol-2-yl)-4-phenyl butane-1,4-dione and [1,2,4]triazolo[3,4-b][1,3,4]thiadiazin-3-yl)butane-1,4-dione; respectively. Furthermore, all the synthesized compounds were confirmed through spectral analysis. Moreover, the synthesized heterocyclic exhibited anti-tumor activity against HepG2 and MCF-7 cell lines, which confirmed these results through docking simulation with PDBID:4hqd and PDBID:5h38 and showed different binding affinity and confirmed the experimental results. Additionally; computational and experimental mechanical studies of compounds 3,5,6,7, 8, 9, and 10 optimized and obtained their physical descriptors via DFT/ B3LYP/6-311G(d) level and showed their stability of them.

Synthesis of some new 2-mercaptobenzoxazol and study their biological activity against some plant pathogenic fungi

The research included synthesis of 2-mercapto benzoxazole (MBO) (1) ) from the reaction of ortho hydroxyl aniline with carbon disulfide in ethanolic potassium hydroxide. The hydrazine benzoxazole HMBA2 (2) was synthesized from the reaction of compound MBO (1) with hydrazine hydrate in presence of alcohol. Compounds (3(a- e)) were synthesized by condensate on of substituted Benzaldehydes with 2-Hydrazino benzoxazole HMBA2. The Ethyl2-(benzoxazolylthio) acetate EMBA1 (4) obtained from the reaction of compound MBO (1) with solution of ethyl chloro acetate using KOH alcoholic .Finally the compound hydrazide HMBA(5 (a- e)) was synthesized from the reaction of compound (4) with hydrazine hydrate in presence of alcohol .All these synthesized compounds were characterized on the basis of their 1H-NMR ,IR, The study is Showed biological activity for chemical compounds, at three concentration 100, 200, 300 ppm in toxic potato Dextrose Agar (PDA) medium method against phytopathogenic fungi three species Fusariumgraminarium, Sclerotiniasclerotium and Rhizoctoniasolani, its isolation on nutritious PDA medium from root plants wheat ,eggplant and cotton continually, diameter measure of fungi growth colony result showed all compound growth inhibition barring MMBA compound non effective inhibition its, appear MBO moral superiority after bring HMBA2 both induce inhibition amount 49.69 and 34.22% continually. Compound concentration its average effect result reveal third significant superior on first and second concentration, interference effect concentration and species chemical compound notice higher inhibition amount 100%with third concentration MBO compound all test its fungi .

Microwave Induced Synthesis of 1,2,4-triazole derivatives and Study of their Anthelmintic and Anti-microbial Activities

Microwave-assisted chemical reactions are utilized as an emerging tool in drug synthesis as this technique is simple, economic, and efficient. So, a new series of 1,2,4-triazole derivatives are obtained via multi-component reactions under microwave irradiation. First of all, benzohydrazide was obtained by esterification of benzoyl chloride with methanol in presence of concentrated sulphuric acid followed by reaction with hydrazine hydrate. So, carbon disulfide was added dropwise to benzohydrazide in ethanolic potassium hydroxide solution to yield potassium dithiocarbazinate which was cyclized by reacting with hydrazine hydrate to afford 1,2,4-triazole-3-thiol. Further, various Schiff’s bases were prepared by reacting 1,2,4-triazole-3-thiol with different substituted benzaldehydes under microwave irradiations. The characterization of the newly synthesized triazole derivatives were carried out by spectral studies including FT-IR, 1H-NMR, and LC-MS. The tested compounds exhibited significant in-vitro anthelmintic and antimicrobial activities as compared to the standard drugs.

Synthesis of Isoindoline-1,3-Dione Derivatives as Cyclooxygenase (Cox) S Inhibitors

Inflammation is the vital part of the immune system's response to injury and infection. It is the body's way of signaling the immune system to heal and repair damaged tissue. The objective of this paper is to design and synthesize a new isoindoline 1,3-dinoe derivative and investigate their selective anti inflammatory activity to COXs. As a potential anti-inflammatory compound, Isoindoline-1,3-dione derivatives were synthesized from the addition reaction of phthalimide, formaldehyde, catalytic amount of potassium hydroxide and cyclic amine in ethanol yielded the desired Isoindoline-1,3-dione compounds (ZJ1-ZJ6. 1H- NMR, ¹³C-NMR, FT-IR and elemental analysis were consistent with the assigned structures. Isoindoline-1,3-dione derivatives exhibited good inhibitory activity against the COX enzymes. To explain the result of our investigation to COX-1 and COX-2 and the selectivity of our compounds to either COX-1 or COX-2, the rationalization in COX-1, the amino group participate more effectively in binding with the ligand while in COX-2, the aryl group is more effective in binding to the ligand. The amino acetylenic compounds behave differently toward COXs from our compound. ZJ4 have shown some selective COX-1 ligand efficiency while ZJ1 promised a potent blockage and ligand efficiency toward the COX-2 enzyme which was found to be higher than the marketed drug Indomethacin and near potency score of Celecoxib. For the first time, this indicates the requirement of investigating the removal of acetylenic group in this study showed that it might be a different binding site in COXs which may result in effective compounds.

Synthesis of Novel Bis(Sulfanediyl)Bis(Tetrahydropyrimido[4,5-b]Quinoline-4,6-Diones) Linked to Butenyl and Butynyl Spacers via Thioether Linkages

A synthesis of novel bis(tetrahydropyrimido[4,5-b]quinoline-4,6-diones) connected to butenyl and butynyl spacers via thioether linkages is reported. Two equivalents of the appropriate aldehyde and dimedone were used in a multicomponent reaction with the corresponding bis(6-aminopyrimidin-4(3H)-ones) to produce the target products. Bis(alkylation) of the appropriate 2-thioxohexahydropyrimido[4,5-b]quinoline-4,6-dione in ethanolic potassium hydroxide with 1,4-dichlorobut-2-ene or 1,4-dibromobut-2-yne also produced the target compounds. Furthermore, bis(tetrahydropyrimido[4,5-b]quinolinetriones) linked to olefinic or acetylenic spacers via ether linkage were synthesized in high yields by a three-component reaction of the appropriate bis(aldehydes) with two equivalents of both 6-aminothiouracil and dimedone.

Synthesis of Schiff’s Bases of 1,2,4-Triazole Derivatives under Microwave Irradiation Technique and Evaluation of their Anti-diabetic Activity

Background: Schiff bases play a key role in the generation of a large number of biologically active compounds via cycloaddition, replacement, and ring closure reactions. Objective: The objective of this study is to optimize the purity and yield of the product, improve the reaction time, and make the reaction more eco-friendly with the help of microwave-assisted organic synthesis. Methods: New series of Schiff’s bases of triazole derivatives were achieved via multicomponent reactions. The starting material benzohydrazide 1 was obtained by esterification of benzoyl chloride with methanol in the presence of concentrated sulphuric acid, followed by the reaction with hydrazine hydrate. Benzohydrazide was allowed to react with carbon disulphide in ethanolic potassium hydroxide solution to yield potassium dithiocarbazinate 2, which undergoes cyclization by reacting with hydrazine hydrate to afford 4-[amino]-5-phenyl-4H-1,2,4-triazole-3-thiol (3). Further, various Schiff’s bases, 4a-f, were obtained by reacting 1,2,4-triazole-3-thiol with different substituted benzaldehydes under microwave irradiations as a green and eco-friendly energy source. Results: The structures of the newly synthesized compounds were elucidated in accordance with their spectral data and elemental analysis. Conclusion : The obtained compounds exhibited significant in vivo anti-diabetic activity as compared to the standard drug Metformin. The anti-diabetic effect was investigated by using the Alloxan-induced diabetic model.

Measurement of Steroid Fatty Acyl Esters in Blood and Brain

Steroid fatty acyl esters (FAEs) are a class of steroid conjugates that are abundant in circulation, have long half-lives, and are stored in lipid-rich tissues. Steroid-FAEs are present in many species, but their functions are poorly understood. They can be metabolized to active, unconjugated steroids and therefore may act as a reservoir of steroids. Dehydroepiandrosterone (DHEA) is an androgen precursor that can be conjugated to various fatty acids. DHEA also modulates aggression in several species, including songbirds, rodents and humans. Recent studies suggest that DHEA-FAEs might be present in songbird blood and/or brain, in part, to regulate aggression. Here, we (1) investigated the abundance of multiple fatty acids in songbird blood and (2) developed an indirect method to measure DHEA-FAEs in songbird blood and brain. First, preliminary work demonstrated high circulating levels of total (esterified and non-esterified) fatty acids, especially oleic, linoleic, and palmitic acids. These data, in conjunction with previous research, suggest that these fatty acids might be conjugated to steroids, including DHEA. Second, we successfully developed a saponification technique to indirectly measure DHEA-FAEs. Saponification cleaves the bond between the steroid molecule and the fatty acid, and we then measure the unconjugated steroid. DHEA-FAEs were incubated in 0.5M potassium hydroxide in ethanol for 30 min at room temperature, and steroids were subsequently extracted twice with dichloromethane. Unconjugated DHEA was quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS), the gold standard in steroid measurement. DHEA recovery was 88% using reference standards in neat solution. We validated this method with song sparrow plasma and chicken serum and obtained recoveries of 94-105% with intra-assay variation of 2.6%. Future research will directly measure specific DHEA-FAEs (e.g. DHEA-oleate) in blood and brain using LC-MS/MS. This research will elucidate the possible roles of steroid-FAEs in brain function and the regulation of steroid-dependent behavior. This work may also clarify the identities, levels and functions of steroid-FAEs in other species, including rodent models and humans. These data have implications for basic and clinical neuroendocrinology, offering insights into a possible storage system for steroids that may influence social behaviour.

Synthesis of Isoindoline-1,3-Dione Derivatives as Cyclooxygenase (Cox) S Inhibitors

Inflammation is the vital part of the immune system's response to injury and infection. It is the body's way of signaling the immune system to heal and repair damaged tissue. The objective of this paper is to design and synthesize a new isoindoline 1,3-dinoe derivative and investigate their selective anti inflammatory activity to COXs. As a potential anti-inflammatory compound, Isoindoline-1,3-dione derivatives were synthesized from the addition reaction of phthalimide, formaldehyde, catalytic amount of potassium hydroxide and cyclic amine in ethanol yielded the desired Isoindoline-1,3-dione compounds (ZJ1-ZJ6. 1H-NMR, ¹³C-NMR, FT-IR and elemental analysis were consistent with the assigned structures. Isoindoline-1,3-dione derivatives exhibited good inhibitory activity against the COX enzymes. To explain the result of our investigation to COX-1 and COX-2 and the selectivity of our compounds to either COX-1 or COX-2, the rationalization in COX-1, the amino group participate more effectively in binding with the ligand while in COX-2, the aryl group is more effective in binding to the ligand. The amino acetylenic compounds behave differently toward COXs from our compound. ZJ4 have shown some selective COX-1 ligand efficiency while ZJ1 promised a potent blockage and ligand efficiency toward the COX-2 enzyme which was found to be higher than the marketed drug Indomethacin and near potency score of Celecoxib. For the first time, this indicates the requirement of investigating the removal of acetylenic group in this study showed that it might be a different binding site in COXs which may result in effective compounds.

REGIOSELECTIVITY OF ALKYLATION REACTION OF 2-OXO-(THIO)-3-PHENYL-THIENO[2,3-d]PYRIMIDINONES

The elaboration of easy and affordable highly selective methods for the synthesis of thieno[2,3-d]pyrimidine derivatives, which operate on none toxic reagents and energy-saving techniques, is an urgent task of organic chemistry. Among the large number of functional derivatives of the title heterocycle, the most interesting objects for our research group are 2-oxo-(thio)-3-phenyl-thieno[2,3-d]pyrimidinones, which contain several reactive nucleophilic centers (nitrogen, oxygen and sulfur atoms), which determines their ambidenties in reactions with electrophilic reagents. Many approaches to the introduction of substituents and functional groups into the thieno[2,3-d]pyrimidine system have been developed, among which the alkylation reactions are the most common. In our previous study, we theoretically predicted the regioselectivity of the alkylation of 2-oxo(thioxo)-3-phenyl-thieno[2,3-d]pyrimidin-4-ones and investigated possible influencing factors.In continuation of this study, in order to reliably validate the results of previous computer simulations, we alkylated the title heterocyclic system with a number of alkylating reagents under the same synthetic conditions, which involve the alkylation of the most thermodynamically advantageous anionic form. 2-Oxo-(thio-)-3-phenyl-5,6,7,8-tetrahydro[1]benzothieno[2,3-d]pyrimidinones were used as starting compounds. To provide alkylation conditions for the most thermodynamically advantageous anion, the starting compounds were heated with excess of potassium hydroxide in ethanol until completely dissolving. The resulting solution of the corresponding potassium salts was cooled and kept at room temperature, after which an excess of alkylating reagent was added and kept at room temperature an additional time.As a result of research, a preparative method of alkylation of 2-oxo-(thio-)-3-phenyl-5,6,7,8-tetrahydro[1]benzothieno [2,3-d] pyrimidinones was developed, which corresponds to the principles of green chemistry (operates with none toxic solvents, easy to perform and does not require long-term heating). The sixteen new previously undescribed thieno[2,3-d]pyrimidine derivatives were obtained.

Design, Synthesis, and Antimicrobial Evaluation of Novel [1,2,4]Triazolo[3,4-b][1,3,4]thiadiazepine Derivatives

The title compounds, 3,3′,3″,3′′′-[methylenebis(oxybenzene-5,1,3-triyl)]tetrakis(6,8-diaryl[1,2,4]triazolo[3,4-b][1,3,4]thiadiazepines), were synthesized starting from dimethyl 4-hydroxyisophthalate which was reacted with dibromomethane to obtain tetramethyl 5,5′-[methylenebis(oxy)]di(benzene-1,3-dicarboxylate). The latter was treated with excess hydrazine hydrate, and the resulting tetrahydrazide was converted to tetrakis-1,2,4-triazolyl derivative via cyclization with ethanolic potassium hydroxide, carbon disulfide, and hydrazine hydrate. In the final stage, cyclocondensation with substituted chalcones afforded the target products. The structure of the newly synthesized compounds was confirmed by elemental analyses and FT-IR and NMR spectra, and their antimicrobial activities against some bacterial and fungal strains were estimated by the disc diffusion method.

NUCLEOPHILIC SUBSTITUTION OF THE NITRO GROUP IN 1-SUBSTITUTED 3-NITRO-1 H -1,2,4-TRIAZOLES IN ETHANOLIC POTASSIUM HYDROXIDE

Dehydrochlorination of 1-(2-chloroethyl)-3-nitro-1H-1,2,4-triazole in ethanolic potassium hydroxide is accompanied by nucleophilic substitution of the nitro group by the ethoxy group. The same nucleophilic exchange in 1-substituted 3-nitro-1H-1,2,4-triazoles occurs in methanol and n-propanol solutions of potassium hydroxide.

Nucleophilic substitution of the nitro group in 1-substituted 3-nitro-1H-1,2,4-triazoles in ethanolic potassium hydroxide

Dehydrochlorination of 1-(2-chloroethyl)-3-nitro-1H-1,2,4-triazole in ethanolic potassium hydroxide is accompanied by nucleophilic substitution of the nitro group by the ethoxy group. The same nucleophilic exchange in 1-substituted 3-nitro-1H-1,2,4-triazoles occurs in methanol and n-propanol solutions of potassium hydroxide.

Development and validation of spectrophotometric methods for the sensitive and selective determination of lamotrigine in pharmaceuticals using bromocresol purple

Three simple, selective and sensitive methods have been developed and validated for the determination of lamotrigine (LMT) in pure drug and in tablets. The first method (method A) is based on the formation of ion-pair complex between LMT and the dye, bromocresol purple (BCP) at pH 2.40±0.01 which was extracted into dichloromethane (DCM) and the absorbance of yellow ion-pair complex was measured at 410 nm. In the second and third methods (method B and method C), the drug-dye ion-pair was dissolved either in ethanol and the resulting acid form of the dye was measured at 410 nm or in ethanolic potassium hydroxide and the resulting base form of the dye was measured at 600 nm. Under the optimized conditions, Beer's law was obeyed over 2.0-20.0 μg/mL, 150-1500 ng/mL and 50-600 ng/mL for method A, method B and method C, respectively, and the corresponding molar absorptivity values were 1.018×104, 1.43×105 and 4.21×105 L/mol/cm. The Sandell sensitivity values of 0.0252, 0.0018 and 0.0006 μg/cm2 for method A, method B and method C, respectively, and the corresponding values for limits of detection and quantification were also reported for all three methods. The molar ratio of the formed ion-pair complex was found to be 1: 1 as deduced by Job's method for method A, and the calculated stability constant was also reported. Over the linear ranges applicable, the accuracy and precision of the methods were evaluated on intra-day and inter-day basis; the reported mean accuracy values are 99.50±1.09%, 99.99±1.11% and 100.72±0.62% for method A, method B, and method C, respectively; the relative error (RE) was ≤ 2.57% and the relative standard deviation (RSD) was ≤ 2.01%. Application of the proposed methods to bulk powder and commercial pharmaceutical tablets are also presented.

Efficient synthesis and characterization of novel 2H-[1,4]oxaselenepino[5,6-b]quinolin-3(5H)-ones derivatives

Abstract The present work deals with synthesis and characterization of some of novel 2H-[1,4]oxaselenepino[5,6-b]quinolin-3(5H)-ones derivatives. A series of 2‑chloro-3-formylquinolines (2a-I) were synthesized from substituted acetanilides (1a-I) using available protocol method and a series of 2‑chloro-3-formylquinolines (2a-l) are converted into 3-formyl-2-selenoquinolines (3a-l) using NaHSe. The resulting 3-formyl-2-selenoquinolines (3a-l) on reduction with sodiumborohydride in methanol afforded a diversely functionalized primary alcoholic derivatives (4a-l). These (2-Hydroselenoquinolin-3-yl)methanols (4a-l) on reacts with chloroacetic acid in the presence of aqueous potassium hydroxide in ethanol gives 2-((3-(Hydroxymethyl)quinolin-2-yl)selanyl)aceticacids (5a-l) scaffolds. The title compounds (6a-l) were prepared by the cyclisation of (5a-l) scaffolds in the presence of P2O5 with dioxane as a solvent. The structures of all the newly synthesized compounds were elucidated on the basis of their elemental analysis, IR, 1H NMR,13C NMR and mass spectral data.

Conversion of Benzimidazoles, Imidazothiazoles and Imidazoles into more Potent Central Nervous System Acting Drugs.

Benzimidazole (albendazole), imidazothiazole (levamisole) and imidazole (euconazole) are used in chemotherapy of helminthosis and mycosis respectively, with central nervous system (CNS) side effects. But only a limited number of azole groups are used clinically in the treatment of CNS diseases, which are on increase and could not be cured permanently. Due to increased incidence of more challenging new CNS diseases, there is a need for the synthesis of more potent CNS drugs. Hence, literature studies were carried out for the identification of common pathways for the synthesis of the three groups of compounds, their CNS properties and the possibility of modifying them to potent CNS drugs. Findings have shown that gloxal with formaldehyde in the presence of ammonia can be converted into imidazole, imidazothiazole and benzimidazole via distillation, condensation, alkylation, acylation, oxidation, cyclization, sulphation and amidation. However, agents such as phosphorus pentoxide, ethanolic potassium hydroxide, sodium hypochlorite, sodium hexafluroaluminate, aniline, calcium acetate, calcium benzoate, sodium hydroxide, aromatic aldehydes, bromoketones, alpha dicarbonyl compounds among others are used as reagents. The furan ring(s) may have a strong capability of penetrating CNS for the treatment of neurological disorders. The products from the three groups have agonistic, antagonistic, mixed agonistic and mixed antagonistic depressant and stimulant activities due to the presence of heteroatoms such as nitrogen, oxygen and sulphur. Imidazole may be the most potent with best characteristics of CNS penetrability and activity followed by imidazothiazole and benzimidazole. Azole group is common to all the three classes and may be responsible for some of their CNS effects. The resultant compounds could act via all neurotransmitters, voltage and ligand-gated ion channels and may be chiral.

Halogenation and μH Tautomerism of 7-Benzyl-7,8-dicarba-nido-undecaborate(−1) Anion

Deboration of 1-PhCH2-1,2-C2B10H11 by heating in ethanolic potassium hydroxide afforded Me4N+ [7-PhCH2-7,8-C2B9H11]− which was treated with excess halosuccinimide (NCS, NBS) in acetonitrile or with elemental iodine or bromine in methanol to obtain Me4N+ [7-PhCH2-9,11-X2-7,8-C2B9H9]− (X = Cl, Br, I). The reaction of 1-PhCH2-1,2-C2B10H11 with an equimolar amount of iodine gave a mixture of Me4N+·[7-PhCH2-11-I-7,8-C2B9H10]- and Me4N+[7-C6H5CH2-9-I-7,8-C2B9H10]− at a ratio 1:1.8 due to steric effect of the benzyl substituent. The 11B chemical shifts of each μ-H tautomer of Me4N+ [7-PhCH2-9,11-X2-7,8-C2B9H9]− (X = H, F, Cl, Br, I) were calculated at the DFT level of theory, and their contributions to the average 11B NMR spectrum and the corresponding tautomeric equilibrium constants were determined.

Triterpene alcohols and sterols of Siberian larch (Larix sibirica Ldb.) needles

The composition of triterpene alcohols and sterols in the fraction of Siberian larch (Larix sibirica Ldb.) conifer needles is considered in paper. The needles areextracted with propan-2-ol; resinous substances are extracted with petroleum ether (40–70°C);substances extracted with petroleum ether are divided into free acids and neutral substances. Neutral substances are separated in a silica gel column; eluent - petroleum ether supplemented with diethyl ether. The isolated esters fraction is hydrolyzed with potassium hydroxide in ethanol, and the “bound” acids are separated from unsaponifiable substances. Non-saponified substances are separated by chromatography into 5 fractions of phytosterols, the alcohol components of esters. The fractions are acetylated; the alcohol acetates are separatedonsilica gel with added silver nitrate. The isolated compounds was identified by NMR and GC-MS methods. Cycloartenol (6.82%, hereafter based onunsaponifiable substances), 24-methylenecycloartanol (6.75%), citrastadienol (7.69%), sitosterol (7.18%), cycloevcalenol (0.09%) are identified, obtussifoliol (0.01%), 24-methylenelophenol (0.10%), methyllophenol (1.84%) and campesterol (0.33%).