Presence Of Boron Trifluoride Research Articles

Stereoselective Construction of Acyclic β,β-Disubstituted Enesulfinamides via Conjugate Addition of Organocuprates to α-Substituted α,β-Unsaturated N-Sulfinyl Ketimines.

In the presence of boron trifluoride, conjugate addition of organocuprates to α-substituted α,β-unsaturated N-tert-butanesulfinyl ketimines provides facile access to acyclic β,β-disubstituted enesulfinamides with high ratios of geometric isomers. Diverse and challenging to synthesize, multisubstituted aza-enolates bearing two electronically and sterically similar β-substituents, which are important precursors for asymmetric construction of the less accessible acyclic quaternary or tetrasubstituted stereocenters at the α-position of ketimines, can be efficiently prepared in good yields with high stereocontrol.

Solvent-Free Mechanosynthesis of Polysubstituted 1,2-Dihydroquinolines from Anilines and Alkyne Esters.

A novel one-pot reaction of anilines with acetylenedicarboxylate diesters in the presence of boron trifluoride, iodine, and trifluoroacetic acid or methylsulfonic acid has been developed under solvent-free ball-milling conditions, affording a variety of polysubstituted 1,2-dihydroquinolines bearing multiple ester groups in moderate to excellent yields. The present protocol features mild reaction conditions, short reaction time, and feasibility of large-scale synthesis, providing a facile and practical alternative to 1,2-dihydroquinoline synthesis. Intriguingly, the generated 1,2-dihydroquinolines can be further transformed into quinoline derivatives.

Tandem Cross-Coupling of Alkynyl Sulfides and Alkynyl Sulfoxides/[3,3]-Sulfonium Rearrangement to Construct Tetrasubstituted Furans.

In the presence of boron trifluoride, a variety of alkynyl sulfides and alkynyl sulfoxides undergo tandem cross-coupling/[3,3]-sulfonium rearrangement followed by 5-exo-dig heterocyclization. The strategy provides concise access to novel tetrasubstituted furans in good to high yields with 100% atom-economy efficiency. Further derivatization of the resultant furans was feasible by utilizing the incorporated alkylthio groups.

Synthesis of Tricyclic Diesters

The addition of saturated monobasic C3–C5 carboxylic acids to unsaturated tricyclic ester, tricyclo[5.2.1.02,6]dec-3-en-8-yl propanoate, in the presence of boron trifluoride–diethyl ether complex gave the corresponding tricyclic diesters in 76.8–88.5 wt % yield. The product structure was confirmed by IR and 1H and 13C NMR spectra. The synthesized diesters possess a pleasant odor and can be recommended for use as synthetic fragrance substances in perfumery.

ASPECTS OF DETERMINATION OF THIODIACETIC ACID IN URINE AS BIOMARKERS FOR INDUSTRIAL EXPOSURE TO VINYL CHLORIDE AND 1,2 -DICHLOROETHANE

There was developed and certified the analytical method for the determination of thiodiacetic acid in the urine in the range of from 0.1 to 10µg/cm3. The sample preparation is based on the execution of derivatization of methanol in the presence of boron trifluoride (10 wt%) followed by liquid-liquid microextraction with dimethyl ester the acid. Derivatization reaction was carried out for 15 min at 80°C. Gas chromatographic analysis was performed on a capillary column HP-5ms under the temperature gradient and splitless modes. Mass spectrometric detection occurred during the registration of selective ions (SIM). Identification of derivatives of thiodiacetic acid on the mass chromatograms was carried out by the absolute retention time (10.36 min) and the ratio of peak intensities of detected ions. The random error in the determination of component and the accuracy of the expanded uncertainty does not exceed 2 and 25%, respectively. There was made a comparative evaluation of the content of thiodiacetic acid in the urine of workers of main shops production of PVC with persons of the control group, not involved in the production. The results can be used for the identification of the fact of the exposure to toxic substances and assessment of the level of exposure and biomonitoring, as a component of health interventions for the prevention of occupational and production-related diseases.

Synthesis of N,O,B-Chelated Dipyrromethenes through an Unexpected Intramolecular Cyclisation: Enhanced Near-Infrared Emission in the Aggregate/Solid State.

The first example of the synthesis of mono-N,O-B-chelated dipyrromethene (BODIPY) derivatives through an unexpected intramolecular nucleophilic displacement of the fluorine by alkenols in the presence of boron trifluoride as Lewis acid is reported. The chlorine in the indacene core allowed for further structural modifications through nucleophilic substitutions or palladium-catalysed coupling reactions to afford new fluorophores with tuneable photophysical properties. Their expanded conjugation structure resulted in distinct red-shifted absorption and emission spectra in organic solutions. Furthermore, the twisted steric hindrance of the benzene substitution patterns suppressed aggregation-induced quenching, leading to an enhanced NIR emission in the aggregate/solid state, which was rarely observed for BODIPY dyes. Nanoparticles of the fluorophores formed by the assembly with the polymeric surfactant F127 were successfully used for bioimaging of living cells and for tumour-targeted imaging in a tumour-bearing mouse model.

Novel Biocomposites Based on Sunflower Oil and Alfa Fibers as Renewable Resources

The aim of this work is to develop biocomposites based on modified sunflower oil as resin and short natural fibers from Alfa plants (Stipa tenacissima) as reinforcement. Epoxidized sunflower oil (ESFO) was chemically modified via acrylation reaction to obtain acrylated epoxidized sunflower oil resin (AESFO). The AESFO resin was then copolymerized with styrene as co-monomer in the presence of boron trifluoride (BF3) as cationic initiator and cobalt octoate (Co) as catalyst. Experimental conditions of this modification were optimized by varying styrene, Co and BF3 wt%. The styrene was varied from 30, 40 to 50 wt% while the catalyst (Co) was varied from 0, 0.01, 0.02 to 0.03 wt%. Two different percents of BF3 were considered: 0.5 and 1 wt%. The prepared samples were evaluated according to their appearance and then characterized in terms of tensile properties (stress at break, Young’s modulus and elongation at break) to determine the best ratio of styrene/BF3/Co. Alfa fibers, used as bio-reinforcement, were treated with a 5% NaOH solution and characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and thermo gravimetric analysis (TGA). Biocomposites were prepared by using untreated (UAF) and treated Alfa fibers (TAF) at a ratio of 5 wt% and characterized in terms of tensile properties and morphology by SEM. The best results were obtained with TAF. Then, the ratio of TAF was varied (5, 7.5 and 10 wt%) and the tensile and thermal properties of the biocomposites were characterized. The results showed that the best results were obtained with the ratio of 7.5 wt%.

Synthesis of Isoxazolopyrrolo[2,1-a]isoquinoline, Isoxazolo[5′,4′: 1,2]indolizino[8,7-b]indole, and Isoxazolo-[5,4-a]thieno[2,3-g]indolizine Derivatives by Intramolecular Cyclization of Hydroxylactams Constituting a Fragment of the Pyrroloisoxazole System

6-Hydroxy-5-[2-(naphthalen-1-yl)ethyl]-3a,5,6,6a-tetrahydro-4H-pyrrolo[3,4-d]isoxazol-4-ones in the presence of boron trifluoride–diethyl ether complex underwent cyclization to benzo[f]isoxazolo[5′,4′: 3,4]- pyrrolo[2,1-a]isoquinoline derivatives as mixtures of two diastereoisomers. Analogous cyclization of 6-hydroxy- 5-(naphthalen-1-ylmethyl)-3a,5,6,6a-tetrahydro-4H-pyrrolo[3,4-d]isoxazol-4-ones gave benzo[de]isoxazolo[ 5′,4′: 3,4]pyrrolo[2,1-a]isoquinolines as a single diastereoisomer. The cyclization of 6-hydroxy-5-[2-(1Hindol- 3-yl)ethyl]-6,6a-dihydro-3aH-pyrrolo[3,4-d]isoxazol-4(5H)-ones catalyzed by Sn(NTf2)4 afforded isoxazolo[ 5′,4′: 1,2]indolizino[8,7-b]indol-4(12H)-ones in moderate yields. 6-Hydroxy-5-[2-(thiophen-2-yl)ethyl]-6,6a-dihydro-3aH-pyrrolo[3,4-d]isoxazol-4(5H)-ones were converted to 4,5,10a,10b-tetrahydroisoxazolo- [5,4-a]thieno[2,3-g]indolizin-7(7aH)-one derivatives in the presence of BF3 · Et2O or Sn(NTf2)4.

Postpolymerization modification of a hydroxy monolith precursor. Part III. Activation of poly(hydroxyethyl methacrylate-co-pentaerythritol triacrylate) monolith with epoxy functionalities followed by bonding of glycerol, polyamines, and hydroxypropyl-β-cyclodextrin for hydrophilic interaction and chiral capillary electrochromatography.

In this last part of the series of investigations involving the postpolymerization modification of a hydroxy monolith (OHM) capillary column, the surface hydroxyl groups were first reacted with glycerol diglycidyl ether in the presence of boron trifluoride (BF3 ) to convert the surface into epoxy activated OHM. The column thus activated with epoxy functions was further functionalized with polar compounds such as glycerol and polyamines to yield polyol OHM and polyamine OHM columns, respectively, for use in hydrophilic interaction electrochromatography. In another postpolymerization functionalization of the epoxy-activated OHM, hydroxypropyl-β-CD (HP-β-CD) was grafted onto the epoxy OHM surface to produce HP-β-CD OHM for enantioseparation by CEC (chiral CEC). The polyol OHM capillary column and polyamine OHM capillary columns exhibited the typical hydrophilic interactions columns vis-à-vis polar solutes such as phenolic compounds and nucleobases. The HP-β-CD OHM column was able to resolve some racemic compounds as well as positional isomers. All the columns exhibited good reproducibility from run to run, day to day, and column to column.

Reactions of aromatic compounds with xenon difluoride

Reactions of substituted benzenes C6H5R (R = Me, F, Cl, Br, CF3, NO2) with xenon difluoride in the presence of boron trifluoride–diethyl ether complex in weakly acidic (1,1,1,3,3-pentafluorobutane) and weakly basic media (acetonitrile) have been studied. These reactions lead to the formation of fluorobenzene derivatives FC6H4R (isomer mixture) together with isomeric difluorobenzenes and fluorinated and non-fluorinated biphenyls. The results have been compared with previously reported data obtained in other solvents using other catalysts.

Diversity-Oriented Synthesis of Functionalized Polyheterocycles from Garner Aldehyde

We report a diversity-oriented synthesis of diverse drug-like polyheterocycles from Garner aldehyde derived 1-hydroxy-1,3-dihydroisobenzofuran 20 as a key intermediate. The oxonium-mediated nucleophilic addition of 20 in the presence of boron trifluoride―diethyl ether complex provided enantiopure 1,3-disubstituted 1,3-dihydroisobenzofurans through 1,3-asymmetric induction. Further diversification of 20 allowed the diastereoselective syntheses of drug-like polyheterocycles including the 3-substituted isobenzofuran-1(3H)-one, 2,3-dihydro-1H-isoindol-1-one, and 3,4-disubstituted dihydroisoquinolinone ring systems.

Composite film coatings prepared by cationic polymerization of epoxy-polysiloxane systems

Cationic polymerization of dicyclohexylpropane diglycidyl ether in the presence of boron trifluoride was studied with the aim to prepare hybrid coatings.

ChemInform Abstract: Reactions of Oxiranes. Part 2. Influence of Protecting Groups on the Regioselectivity of Oxirane Cleavage of 2,3-Epoxybicyclo(3.2.0)heptane- 6-ones by Lithium Alkynide in the Presence of Boron Trifluoride.

ChemInform Abstract: Reactions of Oxiranes. Part 2. Influence of Protecting Groups on the Regioselectivity of Oxirane Cleavage of 2,3-Epoxybicyclo(3.2.0)heptane- 6-ones by Lithium Alkynide in the Presence of Boron Trifluoride.

ChemInform Abstract: Preparation of Perfluoroalkyl Azaarenes with a Perfluoroalkyllithium- Boron Trifluoride System.

Abstract In the presence of boron trifluoride, perfluoroalkyllithiums generated in situ from tbe reaction of n-perfluoroalkyl iodides with methyllithium-lithium bromide smoothly added to a carbon-nitrogen double bond of bicyclic azaarenes and diazines to give the corresponding perfluoroalkylated dihydro heterocycles, which often underwent spontaneous aromatization in air. Perfluoroalkylation occurred preferentially at the carbon next to nitrogen in azaarenes even when the carbon atom was occupied by an alkyl substituent. Only one exception observed was the reaction of acridine where a perfluoroalkyl group was introduced at 9 position.

ChemInform Abstract: Reaction of 2-Isoxazolines with Organolithiums in the Presence of Boron Trifluoride.

In the presence of boron trifluoride, 3,4,5-tri-, 3,5,5-tri and 3,5-disubstituted 2-isoxazolines underwent nucleophilic addition of alkyl- and aryllithiums to give 3,3,4,5-, 3,3,5,5-, and 3,3,5-substituted isoxazolidines in moderate to good yields. On the other hand, in the case of 3,4,5,5-tetrasubstituted isoxazolines, the addition did not proceed at all but proton abstraction took place to afford a “ate” complex of isoxazoline anions, formation of which was confirmed by deuteration and the aldol reaction with benzaldehyde.

ChemInform Abstract: An Unprecedented, Tandem Aldol-Grob Reaction Sequence.

The authors report an unprecedented, tandem Aldol-Grob sequence involving the reaction of ketones with aromatic aldehydes in nonnucleophilic solvents in the presence of boron trifluoride. Although a detailed study of the reaction mechanism has not yet been completed, the consistent formation of (E)-alkene products, as well as the fact that aromatic aldehydes appear to be required, would point toward the intermediacy of a carbocation derivative. A reasonable mechanism would involve the formation of the mixed aldol followed by the formation and subsequent nonsynchronous ring opening of a lactol. The proposed fragmentation is reminiscent of two-step Grob fragmentations that have been reported for N-halo-{alpha}-amino acids and cyclobutane hemiacetals as well as the acid-catalyzed fragmentation of {beta}-hydroxy acetals. The authors examined the effect of various acids on the reaction sequence in order to ascertain which would be most efficient. They conclude that boron trifluoride is the most effective of the acids studied in achieving the new tandem condensation-cleavage sequence.

ChemInform Abstract: A Tandem Aldol-Grob Reaction of Ketones with Aromatic Aldehydes.

Abstract Aromatic aldehydes react with ketones to produce(E)-1-aryl-1-alkenes via a tandem Aldol-Grob cleavage reaction sequence. The reaction, initiated by boron trifluoride, also produces a carboxylic acid fragment. Aromatic aldehydes react with ketones in the presence of boron trifluoride to produce(E)-1-aryl-1-alkenes via a tandem Aldol-Grob cleavage reaction sequence. Download : Download full-size image

ChemInform Abstract: Tetraacylethenes as Dienophiles and Hetero Dienes in Two-Step Diels-Alder Reactions.

Oxidation with barium manganate of the enol of tetraacetylethane (10) affords tetraacetylethylene (7a) in good yield. Treatment of the 1,3-diketones 15a and b with iodosobenzene in the presence of boron trifluoride does not result in oxidative coupling yielding 10 and diacetyldibenzoylethane 17, respectively, as has been reported by Moriarty et al. Instead the known difluoroborylenolates 16 are formed. Oxidative coupling of the sodium enolate of 15b with iodine affords the meso-tetraketone meso-17 and diacetyldibenzoylethylene (E)-7b besides small amounts of rac-17 and the bisenol 19. In the presence of 1,4-diazabicyclo[2.2.2]octane, meso-17 and 19 tautomerise yielding identical equilibrium mixtures of meso-17, rac-17, and 19 (26:29:45). Dehydrogenation with 5,6-dichloro-2,3-dicyanobenzoquinone of meso-17 yields (E)-7b and an isomer (77:23) which was assigned structure (Z)-7b on the basis of spectroscopic evidence. – Tetraacetylethylene (7a) reacts with 1,2-dimethylenecyclohexane to afford two different [4+2]cycloadducts, viz. the spirocyclic dihydropyran 25 (30 %) and the tetraacetyloctalin 27. Whereas the latter is stable, the former isomerises to the latter on heating. Formation of both [4+2]cycloadducts and the isomerisation 25 27 are interpreted by invoking the zwitterion 26 as common intermediate. Monoolefines that cannot generate stable carbenium ions don't give [4+2]cycloadducts with 7a. In contrast, α-methylstyrene yields the oxa Diels–Alder product 30. The structures of (E)-7b, 19, 25, and 27 are established by X-ray diffraction analyses.

ChemInform Abstract: Chiral Oxime Ethers in Asymmetric Synthesis. Part 4. Asymmetric Synthesis of N-Protected Amines and β-Amino Acids by the Addition of Organometallic Reagents to ROPHy/SOPHy-Derived Aldoximes.

Addition of organolithium or Grignard reagents to (R)- or (S)-O-(1-phenylbutyl)aldehyde oximes 1 in the presence of boron trifluoride–diethyl ether results in the formation of hydroxylamines 2 in good to excellent diastereoselectivity. Subsequent cleavage of the N–O bond with zinc–acetic acid–ultrasound, and carbamate formation, gives N-protected amines 3 in good enantiomeric purity (77–100% ee). When allylmagnesium bromide was used as the organometallic reagent, the resulting hydroxylamines were converted into β-amino acid derivatives 4 and γ-amino alcohols 5.

10.1007/s11178-008-1007-x

The alkylation of phenol with camphene in the presence of boron trifluoride in glacial acetic acid was accompanied by tandem molecular rearrangement with formation of a mixture of ortho- and para-substituted phenols having 1,7,7-trimethylbicyclo[2.2.1]hept-exo-2-yl and 5,5,6-trimethylbicyclo[2.2.1]hept-exo-2-yl substituents. The same products were obtained by rearrangement of 1,7,7-trimethylbicyclo[2.2.1]hept-exo-2-yloxybenzene under analogous conditions. Similar reactions performed in the presence of aluminum phenoxide as catalyst resulted in predominant formation of the corresponding ortho-substituted phenols.