Showing papers on "Boron trifluoride published in 2004"
TL;DR: A carbonylative cross-coupling reaction under a carbon monoxide atmosphere is also found to give the corresponding diaryl ketone with a similar catalyst system.
130 citations
TL;DR: The reaction of ring-closing metathesis-derived cyclic allylsiloxanes 3 with aldehydes in the presence of a Lewis acid gives 2,3,4-trisubstituted tetrahydrofurans related to the furanolignan family of natural products.
Abstract: The reaction of ring-closing metathesis-derived cyclic allylsiloxanes 3 with aldehydes in the presence of a Lewis acid gives 2,3,4-trisubstituted tetrahydrofurans related to the furanolignan family of natural products. The reactions proceed with complete 3,4-trans stereoselectivity, whereas the C-2 stereochemistry depends on both the aldehyde and Lewis acid used. When boron trifluoride etherate is used with aliphatic or electronically neutral aryl aldehydes, the reactions favor the production of the 2,3-cis isomer 8, whereas electron-rich aryl aldehydes lead to the 2,3-trans isomer 9 by Lewis acid-mediated isomerization of the kinetically favored cis isomer. The isomerization can be avoided by use of TMSOTf as a promoter, and hence, the stereochemistry can be tuned by appropriate choice of reagent. Cleavage of the pendant 3-ethenyl group installs the 3-hydroxymethyl group common to the furanolignans.
67 citations
TL;DR: Highly crystalline oligopyrene nanowires have been prepared by template-assisted electropolymerization of pyrene in boron trifluoride diethyl etherate medium, which can emit strong blue, green or red fluorescence as excited at 405, 488 or 543 nm, respectively.
62 citations
TL;DR: Alkylation of silyl enolates with tert-alkyl or allylic fluorides proceeds smoothly in the presence of a catalytic amount of boron trifluoride to afford the corresponding carbonyl compounds as discussed by the authors.
60 citations
TL;DR: In this article, a ladder-polymer was constructed using a 3,6-diacyl-2,7-dibromocarbazole building block 4.
Abstract: New carbazole-based ladder-polymers have been prepared utilising a 3,6-diacyl-2,7-dibromocarbazole building block 4. Suzuki polycondensation of 4 with carbazole-2,7-diboronic acid followed by addition of methyl lithium and ring closure with boron trifluoride gave ladder-polymers 9 with all methine bridges, analogous to ladder-type poly(para-phenylene). In very dilute solution, these polymers show blue-green fluorescence similar to that from the corresponding LPPP. At higher concentrations, a broader red-shifted emission is seen which suggests that the chains are aggregating in solution. Homopolymerisation of 4 followed by condensation of the carbonyls with boron sulfide-produced a novel ladder-type structure 13 with alternating five- and six-membered rings. This ladder-polymer displays bright yellow-green fluorescence. Cyclic voltammetry indicated that these materials have HOMO energy levels comparable to the work function of ITO, making them good candidates for use as hole accepting emissive materials for LEDs.
54 citations
TL;DR: In contrast to the previous results for the reaction with areneboronic acids, in which an additional Lewis acid such as boron trifluoride is essential for the activation of the 1-aryltriazenes, the Lewis acidity of organotrifluorosilanes seems to be strong enough to directly activate the triazene moiety to enter into the palladium-catalyzed cross-coupling reaction without an extra Lewis acid as mentioned in this paper.
Abstract: The palladium-catalyzed cross-coupling reaction of 1-aryltriazenes with aryl- and alkenyltrifluorosilanes occurs readily at room temperature to yield the corresponding biaryl and stilbene products in moderate to good yields. In contrast to the previous results for the reaction with areneboronic acids, in which an additional Lewis acid such as boron trifluoride is essential for the activation of the 1-aryltriazenes, the Lewis acidity of organotrifluorosilanes seems to be strong enough to directly activate the triazene moiety to enter into the palladium-catalyzed cross-coupling reaction without an extra Lewis acid.
32 citations
TL;DR: Treatment of tertiary alkyl fluoride with diphenylphosphine in the presence of a stoichiometric amount of boron trifluoride etherate yields the corresponding tert-alkyldiphenyl phosphine despite the coexistence of the strong Lewis acid and the highly coordinating phosphine.
31 citations
TL;DR: In this article, the boron trifluoride etherate, BF3OEt2, was used as an activator towards bis(acetylacetonate)palladium precursor in the polymerization of norbornene.
30 citations
TL;DR: In this article, the structures of the Lewis acid−amine complexes were elucidated using NMR spectroscopy and a plausible reaction mechanism was presented, based on DFT calculations, which preferentially proceed, after deprotonation, via an endo transition state.
Abstract: Boron trifluoride and BBr3 mediated [2,3]-sigmatropic rearrangements of allylic α-amino amides have been developed affording secondary amines in good yields. (E)-Crotyl and (E)-cinnamyl α-amino amides 2b and 2c exhibit excellent syn-diastereoselectivity upon rearrangement with either Lewis acid. The allylic amine 2a forms upon treatment with BF3 or BBr3 a five-membered heterocylic complex in which a single halide anion has been displaced by the carbonyl oxygen atom. The structures of the Lewis acid−amine complexes were elucidated using NMR spectroscopy. A plausible reaction mechanism, based on DFT calculations, is presented. Thus, BF3- or BBr3-complexed allylic amines 2 are shown to preferentially proceed, after deprotonation, via an endo transition state.
30 citations
TL;DR: Ring-opening hydrofluorination of enantiomerically pure 3-aryl glycidyl ethers by boron trifluoride-diethyl ether under mild conditions provides β-fluoro alcohols in good yield in a stereospecific manner with complete regiocontrol.
27 citations
TL;DR: In this article, a 3-phenylthiophene (P3PhT) film with tensile strength of 32-40 MPa has been obtained for the first time, and the morphology and the structure of the polymer film have been studied by scanning electron microscopy, infrared and Raman spectroscopies.
TL;DR: In this article, a procedure for the synthesis of 1,2,4,5-tetraoxanes based on the reaction of gem-bishydroperoxycycloalkanes with ketals and acetals catalyzed by boron trifluoride etherate was developed.
Abstract: A convenient procedure was developed for the synthesis of 1,2,4,5-tetraoxanes based on the reaction of gem-bishydroperoxycycloalkanes with ketals and acetals catalyzed by boron trifluoride etherate, which makes it possible to prepare the target products in yields from 13 to 93%.
TL;DR: In this paper, the authors showed that TFA can significantly decrease the oxidation potential of toluene and also proved the properties of as-formed polymer films in infrared and Raman spectra.
Abstract: Poly(methylphenylene) (PMeP) films were prepared by direct oxidation of toluene in the mixed elec- trolytes of boron trifluoride diethyl etherate (BFEE) and trifluoroacetic acid (TFA). The oxidation potential of toluene in pure BFEE was measured to be 1.52 V versus saturated calomel electrode (SCE). This value was much lower than that determined in a neutral medium such as acetonitrile (2.13 V versus SCE). The introduction of TFA into BFEE decreased the oxidation potential of toluene and also im- proved the properties of as-formed polymer films. Infrared and Raman spectra confirmed the formation of PMeP films. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 189 -195, 2004
TL;DR: The first total synthesis of the β-carboline alkaloids arenarine A (1) and arenarine B (2) was described in this paper, where a homolytic methylation of norharmane (4) with tert-butyl hydroperoxide/ferrous sulfate was performed.
TL;DR: In this article, 2-riorganostannyl oxazolidines were involved in reactions with organocuprates promoted by boron trifluoride, and they gave stereoselectively the enantioenriched N-Boc (a-aminoalkyl)triorganstannanes whose absolute configuration of the major isomer was determined by an X-ray analysis.
TL;DR: In this article, the boron trifluoride nitromethane adduct was evaluated and its thermodynamic and physical properties related to large-scale isotopic separation was presented.
TL;DR: In this paper, the reaction of aziridines and boron trifluoride in high regioselectivity and in high yield was described, and all three fluorine atoms of BF 3 -OEt 2 were incorporated into the products when it reacted with aziridsines.
Abstract: β-Fluoro amines were prepared from the reaction of aziridines and boron trifluoride in high regioselectivity and in high yield. All three fluorine atoms of BF 3 -OEt 2 were incorporated into the products when it reacted with aziridines.
15 Jun 2004
TL;DR: The structures, interaction energies, and vibrational spectra of a series of molecular complexes containing boron trifluoride as the electron acceptor and a variety of oxygen, nitrogen, sulfur, and halogen bases as the donor have been computed in this article.
Abstract: The structures, interaction energies, and vibrational spectra of a series of molecular complexes containing boron trifluoride as the electron acceptor and a variety of oxygen, nitrogen, sulfur, and halogen bases as the electron donors have been computed. The effects of the molecular interactions on the vibrational properties of the boron trifluoride species have been studied, and the degree of perturbation has been correlated with some of the properties of the bases.
Keywords:
ab initio calculations;
van der Waals complexes;
molecular structures;
interaction energies;
vibrational spectra;
boron trifluoride
TL;DR: Aluminum benzyl alcoholate bis(2,6-di-tert-butyl-4-methylphenolate) (BnOAD) as mentioned in this paper successfully polymerized four-membered cyclic ethers in a coordinate anionic ring opening manner.
Abstract: Aluminum benzyl alcoholate bis(2,6-di-tert-butyl-4-methylphenolate) (BnOAD), which was prepared through the mixing of equimolar amounts of benzyl alcohol and methylaluminum bis(2,6-di-tert-butyl-4-methylphenolate) (MAD), successfully polymerized four-membered cyclic ethers in a coordinate anionic ring-opening manner. The polymerization of 3-(4-bromobutoxymethyl)-3-methyloxetane (OxBr) with 5 mol % BnOAD proceeded slowly in toluene at 25 °C and produced sufficiently high-molecular-weight poly(OxBr) in a moderate yield in 24 h. The polymerization was greatly accelerated by the addition of a sterically hindered Lewis acid such as MAD, and this resulted in a nearly quantitative polymer yield within 24 h. In sharp contrast, conventional cationic polymerization with boron trifluoride etherate as a typical Lewis acid initiator produced low-molecular-weight poly(OxBr) along with a substantial amount of the cyclic tetramer. The polymerization of the simplest unsubstituted oxetane with BnOAD resulted in failure.
Patent•
17 Aug 2004TL;DR: In this paper, a process for reducing boron trifluoride usage and emissions associated with PAO manufacture is proposed, which is based on distillation of a portion of the crude PAO product containing a BORON-TRF-OCO catalyst.
Abstract: A process for reducing boron trifluoride usage and emissions associated with PAO manufacture, the process comprising distilling a portion of the crude PAO product containing a boron trifluoride-organic catalyst at a temperature sufficient to cause the boron trifluoride-organic catalyst to dissociate to produce an overhead stream comprising uncomplexed boron trifluoride and an uncomplexed organic catalyst component, contacting the uncomplexed boron trifluoride and uncomplexed organic catalyst component in a condenser column having an internal structure that increases the recombination of the uncomplexed boron trifluoride and uncomplexed organic catalyst component to form a recycle boron trifluoride-organic catalyst.
TL;DR: A stereoselective and synthetically useful rearrangement reaction of 5α,8α-bridged 9,11α-epoxy steroids induced by boron trifluoride−diethyl ether is presented in this article.
TL;DR: A plausible mechanism is proposed for these reactions, which involves the attack on the epoxy ring system by BF3, followed by deprotonation, oxo formation, and double bond migration to give a mixture of two positional α,β-unsaturated C18 enone ester derivatives.
Abstract: The reaction of methyl 11, 12-E-epoxy-9Z-octadecenoate (1) with boron trifluoride etherate furnished a mixture of methyl 12-oxo-10E-octadecenoate (3a) and methyl 11-oxo-9E-octadecenoate (3b) in 66% yield. Methyl 9, 10-Z-epoxy-11 E-octadecenoate (2) with boron trifluoride etherate furnished a mixture of methyl 9-oxo-10 E-octadecenoate (4a, 45%) and methyl 10-oxo-11 E-octadecenoate (4b, 19%). A plausible mechanism is proposed for these reactions, which involves the attack on the epoxy ring system by BF3, followed by deprotonation, oxo formation, and double bond migration to give a mixture of two positional α,β-unsaturated C18 enone ester derivatives (3a/3b, 4a/4b). The structures of these C18 enone ester derivatives (3a/3b, 4a/4b) were identified by a combination of NMR spectroscopic and mass spectrometric analyses.
TL;DR: In this paper, the molecular mechanism of the Diels-Alder reaction between (E )-methyl cinnamate and cyclopentadiene has been characterized by means of density functional theory method at the B3LYP/6-31G* theory level.
TL;DR: In this article, the boron trifluoride etherate-promoted transformation of 2-(methoxyethoxymethoxy)benzyloxyacetaldehyde dimethyl acetals was proposed.
TL;DR: In this article, a mixture of boron trifluoride etherate and acetic anhydride was used to obtain fully aromatized tetralones, which were then used to synthesize dimethoxy tetralin.
Patent•
30 Apr 2004
TL;DR: In this article, a process for synthesizing paracetamol by catalysis, hydrogenation, and acylation in acid medium was described, where nitrobenzene was used as raw material, load type metal platinum is used as the catalyst, and para amino phenol was obtained through hydrogenation.
Abstract: The invention relates to a process for synthesizing paracetamol by catalysis, hydrogenation and acylation in acid medium, wherein nitrobenzene is used as raw material, load type metal platinum is used as the catalyst, and para amino phenol is obtained through nitrobenzene hydrogenation in boron trifluoride ether and aqueous solution, the APAP is prepared through rearrangement reaction synthesis and acetylation.
Patent•
20 Jan 2004
TL;DR: In this paper, a process for the preparation of lithium borohydride by reaction of lithium hydride with boron trifluoride is described, in which lithium hyddride is reacted with bors trifluride in a molar ratio LiH:BF 3 of > 4.1:1, the reaction being carried out in an ethereal solvent whose boiling point at normal pressure at least 50° C, and at temperatures of at least 10° C.
Abstract: A process for the preparation of lithium borohydride by reaction of lithium hydride with boron trifluoride is described, in which lithium hydride is reacted with boron trifluoride in a molar ratio LiH:BF 3 of >4.1:1, the reaction being carried out in an ethereal solvent whose boiling point at normal pressure is at least 50° C., and at temperatures of at least 10° C.
TL;DR: In this article, the relative reactivity of 4-methylpyridines, their N-oxides and their Lewis acid complexes towards electrophilic reaction was compared with the reaction of BF 3 complexes with electrophile in the presence of LTMP-TMEDA.
Abstract: The comparative studies were carried out on the relative reactivity of 4-methylpyridines, their N-oxides and their Lewis acid complexes towards electrophilic reaction. α-Deprotonation in pyridine ring rather than deprotonation of active methyl group or metal-halogen exchange occurred preferentially in the reaction of N- and N-oxides BF 3 complexes with electrophile in the presence of LTMP-TMEDA in THF to give a -substituted-4-methylpyridines and their N-oxides.
TL;DR: In the presence of boron trifluoride etherate, some kinds of aliphatic ethers have been found to react with benzaldehyde dimethyl acetal yielding α,β-unsaturated carbonyl compounds with evolution o...
Abstract: In the presence of boron trifluoride etherate, some kinds of aliphatic ethers have been found to react with benzaldehyde dimethyl acetal yielding α,β-unsaturated carbonyl compounds with evolution o...
Patent•
27 Oct 2004
TL;DR: In this paper, a process for preparing boron nitride from trifluoride ether and lithium nitride by solvent heat synthesis method includes adding benzene as solvent in reactor, adding lithium n-tric acid, stirring, closing reactor, heating to 250-500 deg.C, holding the temp, cooling, dissolving in ionized water, centrifugal separation of supernatant, repeating the dissolving and separation steps, immersing in solution of hydrochloric acid, water washing, and drying.
Abstract: A process for preparing boron nitride from boron trifluoride ether and lithium nitride by solvent heat synthesis method includes adding benzene as solvent in reactor, adding lithium nitride, stirring, adding boron trifluoride ether, stirring, closing reactor, heating to 250-500 deg.C, holding the temp, cooling, dissolving in ionized water, centrifugal separation of supernatant, repeating the dissolving and separation steps, immersing in solution of hydrochloric acid, water washing, centrifugal separation of deposit, and drying.