Showing papers on "Boron trifluoride published in 1992"
Patent•
22 Jun 1992
TL;DR: In this paper, a process for preparing highly reactive polyisobutenes with a content of terminal vinylidene groups of more than 80 mol % and an average molecular weight of 500-5000 Dalton by the cationic polymerization of isobutene or isomethane-containing hydrocarbon feeds in liquid phase with the aid of boron trifluoride as catalyst and at from 0° C. to -60° C., comprises polymerizing in the presence of secondary alcohols with 3-20 carbon atoms and/or ethers with 2
Abstract: A process for preparing highly reactive polyisobutenes with a content of terminal vinylidene groups of more than 80 mol % and an average molecular weight of 500-5000 Dalton by the cationic polymerization of isobutene or isobutene-containing hydrocarbon feeds in liquid phase with the aid of boron trifluoride as catalyst and at from 0° C. to -60° C., comprises polymerizing in the presence of secondary alcohols with 3-20 carbon atoms and/or ethers with 2-20 carbon atoms.
169 citations
TL;DR: In this article, a 1:1 complex of BF3 and 2-methylacrolein has been isolated and shown to have molecular structure 1H NMR molecular dynamics and NOE studies have demonstrated that the same s-trans structure predominates at 185 K in CD2Cl2 solution.
40 citations
TL;DR: In this paper, a new annulation method involving a boron trifluoride catalysed addition of trialkylsilyl enol ethers to methyl vinyl ketone (MVK) in the presence of a hydroxylic compound was presented.
Abstract: A new annulation method is presented, involving a boron trifluoride catalysed Michael addition of trialkylsilyl enol ethers to methyl vinyl ketone (MVK) in the presence of a hydroxylic compound. This methodology allows regiospecific 3-oxobutylation of either of the two isomeric enol ethers of mono or di-substituted cyclanones. Octalones 2d, e and hydrindenones 17 with the two alkyl groups in a cis relationship can thus be specifically obtained. This method has been applied to a short and efficient preparation of (±)-dehydrofukinone 10.
36 citations
TL;DR: In this paper, the synthesis and reactions of two epoxyketoacids (methyl (Z)-9,10-epoxy-13-oxo-(E)-11-octadecenoate (IV) and methyl (E)- 9,10 -epoxy -13oxo-11-hexagonal-oxide (V) are described.
34 citations
TL;DR: In this paper, the synthetic routes and properties of new tris(fluoroaryl)boranes are described and the syntheseverfahren and die Eigenschaften der meist neuen Verbindungen werden beschrieben.
Abstract: B(2-FC6H4)3, B(4-FC6H4)3, B(2,6-F2C6H3)3 und B(C5F4N)3 werden durch Reaktionen von RMgX mit Bortrifluorid, B(OC6F5)3 und B(SC6F5)3 aus C6F5XH (X = O, S) mit Bortrichlorid dargestellt. Die Syntheseverfahren und die Eigenschaften der meist neuen Verbindungen werden beschrieben.
Preparation and Properties of New Tris(fluoroaryl)boranes
B(2-FC6H4)3, B(4-FC6H4)3, B(2,6-F2C6H3)3 and B(C5F4N)3 are prepared from the reactions of RMgX with boron trifluoride, B(OC6F5)3 and B(SC6F5)3 from C6F5XH (X = O, S) and boron trichloride. The synthetic routes and the properties of these mainly new compounds are described.
32 citations
TL;DR: In the presence of BF 3 -OEt 2, (perfluoroalkyl)lithiums generated in situ from the reaction of primary perfluoro-alkyl iodides and MeLi-LiBr reacted with imines, azines, and nitrones to afford perfluoralkylated nitrogen-containing compounds in moderate to good yields as discussed by the authors.
Abstract: In the presence of BF 3 -OEt 2 , (perfluoroalkyl)lithiums generated in situ from the reaction of primary perfluoroalkyl iodides and MeLi-LiBr reacted with imines, azines, and nitrones to afford perfluoroalkylated nitrogen-containing compounds in moderate to good yields. This method was successfully applied to the preparation of a (perfluoroalkyl)glycine and optically active perfluoroalkylated amines
30 citations
TL;DR: It was found that complete methanolysis of sphingomyelin takes 15 h at 90 degrees C and only the sodium methoxide-catalysed method at ambient temperature gave complete meethanolyism of phosphoglycerides.
30 citations
29 citations
TL;DR: Boron trifluoride monohydrate catalyzed thiolation of aldehydes and ketones with thiols and triethylsilane to the corresponding sulfides was carried out in good to excellent yields as discussed by the authors.
Abstract: Boron trifluoride monohydrate catalyzed thiolation of aldehydes and ketones with thiols and triethylsilane to the corresponding sulfides was carried out in good to excellent yields
29 citations
TL;DR: The syn-CH 3 CHO-BF 3 complex is only 1.22 kcal mol -1 less stable than the corresponding anti-Ch 3CHO-BF3 complex at the MP2/6-31G* level of theory as discussed by the authors.
Abstract: The syn-CH 3 CHO-BF 3 complex is only 1.22 kcal mol -1 less stable than the corresponding anti-CH 3 CHO-BF 3 complex at the MP2/6-31G* level of theory. The corresponding difference in syn- and anti-PhCHO-BF 3 complexes is 5.31 kcal mol -1 . The calculated C-C=O (129 o ) and C-O-B (156 o ) angles for syn-PhCHO-BF 3 complexes have a much greater deviation from the standard geometries of a sp2 orbital than that (123.9 o and 125.4 o ) calculated for syn-CH 3 CHO-BF 3 complexes
27 citations
TL;DR: In this paper, the authors used 13 C signals of unsaturated ketones at infinite dilution in the investigated acid established by the authors was applied to the system boron triftuoride-water (III) ranging from the monohydrate (BF 3 · H 2 O) to the trihydrate (BF 2 · 3H 2 O).
TL;DR: Potassium nitrate/boron trifluoride monohydrate and nitric acid/bron trifluride monoxide have been found to be efficient reagents for the nitration of aromatic compounds.
Abstract: Potassium nitrate/boron trifluoride monohydrate and nitric acid/boron trifluoride monohydrate have been found to be efficient reagents for the nitration of aromatic compounds. Benzene and a series of substituted benzenes were nitrated with excellent yields
TL;DR: The expected beta glycosides were transformed in good yields, via selective reduction of the azido group, coupling with octadecanoic acid, O-deacylation, and de-esterification, into the target compounds.
TL;DR: The N-trimethylsilyl imines of O-protected α-hydroxy aldehydes react with RCuMgXI BF 3 to give β-amino alcohols with high anti diastereoselectivity.
TL;DR: In the presence of BF3 etherate, (1-alkynyl)diisopropoxyboranes react with α,β-unsaturated ketones to give 1,4-addition products selectively in good yields as discussed by the authors.
Abstract: In the presence of BF3 etherate, (1-alkynyl)diisopropoxyboranes react with α,β-unsaturated ketones to give 1,4-addition products selectively in good yields.
TL;DR: In this paper, a ring-opening copolymerization in the various ratio of 1,4-anhydro-2,3-di-0-benzyl- and 1, 4-anhexyl-1,5-α-D-ribofuranosidic units and benzylated 1,5α-d-ribopyranoses units was used to synthesize stable (1→5)-β-Dribofurananan derivatives.
Abstract: Stereoregular (1→5)-α-D-ribofuranan (α-D-R) derivatives were synthesized by selective ring-opening copolymerization in the various ratio of 1,4-anhydro-2,3-di-0-benzyl- and 1,4-anhydro-2,3-di-O-(tert-butyldimethylsilyl)- α-D-ribopyranoses with boron trifluoride etherate as catalyst in CH 2 Cl 2 . Selective removal of the silyl groups gave α-D-R which are composed of 1,5-α-D-ribofuranosidic units and benzylated 1,5-α-D-ribofuranosidic units. Branched α-D-R having branches at 2- and/or 3-positions were obtained after reaction with D-mannose, D- and L-glucose orthoesters followed by deprotection
TL;DR: In this paper, the lithium salt of S-benzyl-N-t-butyldiphenylsilyl-S-methylsulfoximine (2) undergoes 1,2-addition to imines that have been activated by precomplexation with boron trifluoride diethyl etherate (BF3.Et2O), and aldehydes, with high diastereoselectivity.
Abstract: The lithium salt of racemic S-benzyl-N-t- butyldiphenylsilyl-S-methylsulfoximine (2) undergoes 1,2-addition to imines that have been activated by precomplexation with boron trifluoride diethyl etherate (BF3.Et2O), and aldehydes , with high diastereoselectivity. The relative lS*,2S.*,S*s stereochemistry of the major diastereomeric adducts of (2) and EtCH = NPh and PriCH = NPh , and the relative lS *,2S*,S*s stereochemistry of the major diastereomeric adduct of (2) and propanal were unequivocally determined by single-crystal X-ray structure analysis. An open transition state has been proposed to account for the stereochemical outcome of these reactions.
TL;DR: The dinuclear camplex [AuIr(CO)CI(μ-dpm) 2 ](PF 6 ) (1; dpm is bis(diphenylphosphino)methane) is unreactive in dichloromethane solution toward substances (trifluoroacetic acid, hydrogen chloride, sulfur dioxide, dihydrogen, tetracyanoethylene) that are known to bind to Ir(CO),Cl(PPh 3 ) 2.
Abstract: The dinuclear camplex [AuIr(CO)CI(μ-dpm) 2 ](PF 6 ) (1; dpm is bis(diphenylphosphino)methane) is unreactive in dichloromethane solution toward substances (trifluoroacetic acid, hydrogen chloride, sulfur dioxide, dihydrogen, tetracyanoethylene) that are known to bind to Ir(CO)Cl(PPh 3 ) 2 . A weak adduct is formed with boron trifluoride. Both 1 and [AuIr(CNMe) 2 (μ-dpm) 2 ](PF 6 ) 2 react with mercury(II) chloride in a two-step process
TL;DR: In this article, a tetrafunctional epoxy resin (largely tetraglycidyldiaminodiphenylsulphone (DDS) and boron trifluoride/ethylamine (BF3EA) catalyst is affected by the presence of an oxidized carbon fiber surface.
Abstract: The cure of a tetrafunctional epoxy resin (largely tetraglycidyldiaminodiphenylmethane, TGDDM), cross-linked with diaminodiphenylsulphone (DDS) and boron trifluoride/ethylamine (BF3EA) catalyst, is affected in a complex fashion by the presence of an oxidized carbon fiber surface. If the fiber is aged in a humid environment (25°C, 95% humidity) before coating with the matrix, the affinity of the oxidized fiber surface for water leads to destruction of the catalyst and retardation of the cure. This retardation is noticeable at lower humidities if the polymer content of the composite is reduced to > 20%. For oxidized fibers that are stored under ambient conditions (40% humidity), the retarding effect of water is overwhelmed by the catalytic effect of the acidic fiber surface. This activates the latent catalyst, increasing the rate of epoxy consumption and the proportion of the epoxy–epoxy reaction relative to the epoxy–amine reaction. For the low-humidity case, even though the rate of chemical reaction is increased, vitrification of the matrix is retarded, implying that there is less cross-linking and more extended epoxy–epoxy sequences in the network. The proposed chemical changes in epoxy/carbon fiber composites were confirmed by analysis of model reactions in solution. © 1992 John Wiley & Sons, Inc.
TL;DR: In this article, the reaction of alcohols with epoxides in the presence of boron trifluoride etherate has been investigated and found to proceed with variable regioselectivity depending on the substituents attached to the oxirane ring.
TL;DR: In this article, the Lewis acid-promoted cyclocondensation between two electron-rich dienes with a series of racemic α-and β-thio-substituted aldehydes has been studied.
Abstract: The Lewis acid-promoted cyclocondensation between two electron-rich dienes with a series of racemic α- and β-thio-substituted aldehydes has been studied. Boron trifluoride etherate proved to be the catalyst of choice, affording satisfactory chemical yields and generally good diastereoselectivities. Other Lewis acidic catalysts gave lower yields and in some cases reversed the sense of the diastereoselection. A rationalization of the stereochemical results is presented
Patent•
09 Apr 1992
TL;DR: In this article, a process for the production of trialkyl acetic acids, particularly of pivalic acid, from branched olefins, particularly isobutene, and carbon monoxide using catalytic amounts of a Lewis acid such as boron trifluoride was described.
Abstract: This invention is a process for the production of trialkyl acetic acids, particularly of pivalic acid, from branched olefins, particularly isobutene, and carbon monoxide using catalytic amounts of a Lewis acid such as boron trifluoride.
TL;DR: In this paper, the β-ketosultames 3 and 11 are transformed by aldol condensation into the corresponding alkylidene derivatives 4, 5, and 12.
Abstract: Die β-Ketosultame 3 und 11 werden durch Aldolkondensation zu den entspr. Alkylidenderivaten 4, 5 bzw. 12 umgesetzt. Epoxidation von 5 und 12 fuhrt zu den Epoxyketonen 6 und 13, die mit Bortrifluorid-Etherat zum 1,2-Thiazin 7 bzw. zum 1,2-Thiazepin 14 isomerisieren.
Synthesis of 1,2-Thiazines and 1,2-Thiazepines by Ring Expansion
The β-Ketosultames 3 and 11 are transformed by aldol condensation into the corresponding alkylidene derivatives 4, 5, and 12. Epoxidation of 5 and 12 leads to the epoxyketones 6 and 13 which isomerize by boron trifluoride etherate to 1,2-thiazine 7 and 1,2-thiazepine 14, respectively.
TL;DR: In this paper, α-Tributylstannylacetals derived from 2 R,3 R -tartramide or 2 R,4 R -pentanediol have been treated with various organometallic reagents to give chiral α-oxygenated organotins.
TL;DR: In this article, a ring expansion of 1-carbethoxy-4-piperidinone 3 with ethyl diazoacetate and boron trifluoride was used to yield 1,5-biscarbethoxyperhydroazepin 4-one 4.
TL;DR: Boron trifluoride monohydrate, an inexpensive superacid, was found to be an efficient catalyst for thioacetalization as discussed by the authors, and it was used as a superacid for the first time.
Abstract: Boron trifluoride monohydrate, an inexpensive superacid, was found to be an efficient catalyst for thioacetalization.
Patent•
21 Jul 1992TL;DR: Acylaromatic compounds are prepared in high yield by a reaction, in the presence of a boron trifluoride complex catalyst, of an aromatic compound with (X: H, Cl, Br; Y: Cl, B, Br) or with RCOOH with (XYCHCO)2 O. as discussed by the authors.
Abstract: Acylaromatic compounds ##STR1## (Q: aromatic compound residue; R: straight, branched or cyclic aliphatic group, aromatic group or araliphatic group) are prepared in high yield by a reaction, in the presence of a boron trifluoride complex catalyst, of an aromatic compound with ##STR2## (X: H, Cl, Br; Y: Cl, Br) or with RCOOH in the presence of (XYCHCO)2 O.
TL;DR: The synthesis of methyl 6-alkylamino-3-pyridazinecarboxylates (4a-c) was accomplished by the following reaction sequence as mentioned in this paper.
Abstract: The synthesis of methyl 6-alkylamino-3-pyridazinecarboxylates (4a-c) was accomplished by the following reaction sequence. On treatment of methyl 6-chloro-3-pyridazinecarboxylate (1) with methanolic ammonia, 6-chloro-3-pyridazinecarboxamide (5) was precipitated almost quantitatively, which reacted with primary alkylamines to give the corresponding 6-alkylamino-3-pyridazinecarboxamide (6a-c). These products were smoothly converted into the methyl esters (4a-c) by treatment with methanol in the presence of boron trifluoride etherate. The reaction of 1 with butylamine in THF gave a complicated mixture in which N-butyl-6-chloro-3-pyridazinecarboxamide(2), N-butyl-6-butylamino-3-pyridazinecarboxamide(3), 4b, and 1 were involved
Patent•
13 Feb 1992
TL;DR: In this paper, the authors obtained the title of boron nitride with higher developmental degree of laminar structure, thus suitable as a material for the crucibles to be used in pulling compound semiconductor single crystal by reaction between a BORON halide, alkyl borate and ammonia under specified conditions.
Abstract: PURPOSE:To obtain the title boron nitride with higher developmental degree of laminar structure, thus suitable as a material for the crucibles to be used in pulling compound semiconductor single crystal by reaction between a boron halide, alkyl borate and ammonia under specified conditions. CONSTITUTION:The objective boron nitride >=1000 in crystal orientation degree can be obtained by the following processes; a reaction is carried out at >=1600 deg.C under a pressure of <=50Torr between a boron halide, an alkyl borate and ammonia. The boron halide is e.g. boron trichloride, boron trifluoride. The alkyl borate is e.g. methyl borate, ethyl borate. The molar ratios for alkyl borate and ammonia are such as to be (0.1-1.0):(2-10) per mol of the boron halide, respectively.
TL;DR: The synthesis of fused tetracyclic naphthothiopyranopyranones from dihydronaphthiotropyranone I or II has been studied in this article.