Showing papers on "Boron trifluoride published in 1990"

Olefin oligomerization with BF3 alcohol alkoxylate co-catalysts

Abstract: A process for making an α-olefin oligomer comprises contacting an α-olefin monomer containing from about 6 to 20 carbon atoms with a catalyst comprising boron trifluoride and an alcohol alkoxylate so as to form an oligomer product.

Polyene synthesis. Ready construction of retinol-carotene fragments, (.+-.)-6(E)-LTB3 leukotrienes, and corticrocin

Abstract: All products of the dirhodium tetraacetate catalyzed reactions of ethyl diazoacetate with furan, 2-methylfuran, 2,5-dimethylfuran, 2-n-octylfuran, methyl furoate and methyl β-(α-furyl)acrylate were isolated and characterized. They consist mostly of exo-cyclopropanecarboxylates and 1,4-diacyl-1,3-butadienes and some 3-(acylmethyl)furans. Treatment of the crude reaction mixtures with iodine or boron trifluoride furnishes 1,4-diacyl-1(E),3(E)-butadienes. Horner-Emmons condensation with the latter dicarbonyl compounds leads to 1,6-diacyl-1,3,5-hexatrienes. Proper combinations of methyl α-diazopropionate, furans, and α-phosphono esters afford segments of retinol and β-carotene, while combinations of α-diazo ketones, furans, and α-phosphono ketones yield LTB 3 -llike leukotrienes. Finally, dirhodium terraacetate promoted decomposition of ethyl diazoacetate in 1,2-bis(2-furyl)ethane and iodine treatment gives a diketo diester, whose reduction, dehydration, and hydrolysis leads to the naturally occurring dodecahexaenic dicarboxylic acid, corticrocin

Cubic boron nitride films deposited by electron cyclotron resonance plasma

Abstract: By employing an electron cyclotron resonance plasma‐enhanced chemical vapor deposition technique, we report the successful growth of cubic boron nitride films on single‐crystal (100) silicon wafer without external rf or dc substrate biasing. Ammonia and boron trifluoride gases were used for the deposition of cubic boron nitride. The substrate temperature during deposition was about 675 °C. The films were characterized by infrared spectroscopy and ellipsometry. The existence of cubic boron nitride was identified by the characteristic boron nitride infrared signal at 1110 cm−1. The film thickness was about 1000 A, with a growth rate of 100 A/min.

Diastereoselective addition of methylcopper- and diemthylcuprate-boron trifluoride reagents to (S)-(N-alkylidine)-1-phenylethylamines

Abstract: The reactions of methylcopper- and diemthylcuprate-boron trifluoride reagents with aldimines derived from (S)-1-phenylethylamine afford with good diastereoselectivity (S,S)-amines from aromatic imines, but the (R,S)-amine from an aliphatic imine.

AN EFFICIENT CONSTRUCTION OF 1, 2-TRANS-β-GLYCOSIDIC LINKAGES VIA BENZYL-PROTECTED GLYCOPYRANOSYL P, P-DIPHENYL-N-(p-TOLUENESULFONYL)-PHOSPHINIMIDATES

Abstract: An efficient 1, 2-trans-glycosidation reaction withon neighbouring group participation has been developed using benzyl-protected P, P-diphenyl-N-(p-toluensulfonyl)phosphinimidates as glycosyl donors in the presence of trimethylsilyl triflate or boron trifluoride etherate.

Self-locking agent

Abstract: A self-locking agent for a fastening device comprises a microencapsulated adhesive composition comprising the following constituents (a) and (d): (a) an epoxy compound having at least two epoxy groups, (b) an aromatic diamine represented by the following formula (a) or (b): wherein R1 to R4 each represent CH3, C2Hs, C3H7, CH(CH3)2, C4H9 or a halogen, or wherein R5 to R7 each represent CH3, C2Hs, C3H7 or a halogen, and (c) at least one compound selected from the group consisting of thiosalicylic acid, salicylic acid, benzoic anhydride, boron trifuloride and boron trifluoride complexes, wherein at least one of the epoxy compound (a) and aromatic diamine (b) is microencapsulated to keep them apart from each other, said self-locking agent has excellent thermal resistance and storage stability.

Aryl fluorides from the reaction of boron trifluoride with aryl-lead(IV) triacetates, which may be generated in situ from aryltrimethylsilanes, triarylboroxines, and arenes

Abstract: Aryl-lead(IV) triacetates react at room temperature with BF3·Et2O to give the corresponding aryl fluoride in moderate to good yields; triarylboroxines, electron-rich aryltrimethylsilanes, and some arenes, which yield aryl–lead(IV) triacetates in acid catalysed reactions with lead tetra-acetate, may be converted directly into aryl fluorides when stirred with lead tetra-acetate in BF3·Et2O

Method for the manufacture of carotinoids and the novel intermediates

Abstract: Phosphonium salts of the formula ##STR1## wherein A signifies aryl and Y- signifies C1 -C6 -alkanoate or hydroxytrifluoroborate, as well as their manufacture from 3,7,11-trimethyldodeca-1,4,6,10-tetraen-3-ol with a triarylphosphine and with a C1 -C6 -alkanoic acid or a boron trifluoride etherate and, if desired after conversion into the phosphonium salt of a strong acid, further reaction to give lycopene.

Regiospecific oxidation of binor S and acid-catalyzed rearrangement of the product to the first example of a pentacyclo[6.6.0.05,14.07,12.09,13]tetradecane

Abstract: Dimethyldioxirane has been found to oxidize the head-to-head dimer of norbornadiene (binor-S) regiospecifically, giving first the 1-ol and then the 1,9-diol of heptacyclo[8.4.0.0 2,7 .0 3,5 .0 4,8 .0 9,13 .0 12,14 ]tetradecane. Reaction of the 1-ol with boron trifluoride etherate induces gross rearrangement and leads in good yield to (±)-pentacyclo[6.6.0.0 5,14 .0 7,12 .0 9,13 ]tetradec-2-en-6-one, the first reported member of this new ring system

Effect of boron trifluoride–diethyl ether (BF3·OEt2) in the Diels–Alder reaction of quinoline- and isoquinoline-5,8-dione with unsymmetrical aliphatic dienes: theoretical study on the orientation of cycloadditions

Abstract: The Diels–Alder reaction of quinoline- and isoquinoline-5,8-dione with piperylene or isoprene gave regioisomers of the substituted azaanthraquinones, while the Lewis acid catalyst boron trifluoride–diethyl ether showed a drastic effect on regioselectivity in the reactions with piperylene. The Frontier Molecular Orbital (FMO) theory (calculated by CNDO/2 method) was applied to explain the orientation of the catalysed regioselective cycloadditions, by considering secondary orbital interactions.

3,7,11-Trimethyl dodeca-2,4,6,10-tetraen-1-yl phosphonium salts

Abstract: Phosphoniumsalze der Formel Phosphonium salts of the formula worin R Aryl und Y⁻ C₁-C₆-Alkanoat oder Hydroxytrifluoroborat bedeuten, wherein R is aryl and Y⁻ C₁-C₆-alkanoate or Hydroxytrifluoroborat mean sowie deren Herstellung aus 3,7,11-Trimethyldodeca-1,4,6,10-tetraen-3-ol mit Triarylphosphin und mit C₁-C₆-Alkansaure oder Bortrifluorid-Aetherat und, gewunschtenfalls nach Ueberfuhrung in das Phosphoniumsalz einer starken Saure, weitere Umsetzung zu Lycopin. as well as their preparation from 3,7,11-trimethyldodeca-1,4,6,10-tetraen-3-ol, with triarylphosphine and with a C₁-C₆ alkanoic acid or a boron trifluoride etherate and, if desired, after conversion into the phosphonium salt of a strong acid further reaction to lycopene.

Boron trifluoride-methanol complex as a non-depurinating detritylating agent in DNA synthesis

Abstract: We have found that boron trifluoride-methanol complex (BTMC) is an effective non-depurinating detritylating agent in automated DNA synthesis. Dichloroacetic acid (DCA) is at present widely used for the deprotection of the 5'-hydroxyl group prior to coupling the next nucleotide (1); however, the protected purine bases, 6'-isobutyryl-2'-deoxyguanosine and 4'-benzoyl-2'-deoxyadenosine, are unstable to acid and can undergo base modification during the deprotection step, leading to depurination and chain cleavage during the final amide deprotection step with ammonium hydroxide. Oligomers which have a high purine content or which have purines clustered near the 3'-end undergo considerable depurination with DCA. Unlike DCA, BTMC (2) does not act as a protonic acid but rather as a Lewis acid by complexing with an electron pair of the ether oxygen. Methanol then supplies the proton necessary to complete the ether cleavage. We compared BTMC as a detritylating agent with DCA in three ways: (i) yield of product, (ii) freedom from base modification, and (iii) template activity.

Epoxy prepolymers cured with boron trifluoride‐amine complexes, 1. Influence of the amine on the curing window

Abstract: Different pure complexes were synthesized by an interchange reaction of BF3-etherate with amines in dichloromethane. All of the resulting complexes are solid, but they can be dissolved in a low-molecular-weight poly(ethylene oxide) to favour their use as initiators. DSC analysis demonstrated strong interactions between the BF3-complex and the polyether. This is probably caused by the formation of hydrogen bonding between the hydrogens of the amine and the ether groups. The reactivity of amine complexes was characterized by reaction with the epoxy prepolymer. The reactivity increases with decreasing basicity of the amine, showing a relationship between the initiation and propagation of the expoxy homopolymerization and the stability of the complex. A slight influence on the reaction temperatures by the amount of polyether is observed, but the glass transition temperature of the epoxy network decreases when a large excess is used.

The ene reaction between N‐isobutylallylnadimide and N‐isobutylmaleimide as a model for the cross‐linking reaction in bis(allyl)nadimide polymerization

Abstract: The reaction between N-isobutylallylnadimide (NIBANI) and N-isobutylmaleimide (NIBMI) was taken as a model reaction to obtain insight into the curing mechanism of polymeric alloys and composites consisting of bis- or tris(allyl)nadimides and bismaleimides. The reaction between NIBANI and NIBMI is not catalyzed by boron trifluoride etherate, neither at room temperature nor in refluxing methylene chloride. The thermally induced reaction (200°C) between NIBANI and NIBMI in equimolar quantities gives an indirect proof for the occurrence of an ene reaction. The high reactivity of the ene reaction product to undergo further Diels-Alder reaction was proved by GPC and direct inlet mass spectral studies.

Boron trifluoride-promoted reaction of 4′-nitrobenzenesulphenanilide with alkynes. Formal addition of benzenesulphenyl fluoride to carbon–carbon triple bonds

Abstract: The BF3-promoted reaction of 4′-nitrobenzenesulphenanilide with simple alkyl- and aryl-alkynes at 80 °C in the presence of tetrabutylammonium tetrafluoroborate provides a one-pot synthetic route to β-fluorovinyl sulphides via a formal regioselective and trans-stereospecific addition of benzenesulphenyl fluoride towards carbon–carbon triple bonds.

A Novel Selenium-Containing Heterocycle. Lewis Acid-Assisted Reaction of Selenoamides with Aldehydes Leading to 6H-1,3,5-Oxaselenazines

Abstract: New selenium-containing heterocyclic compounds, 6H-1,3,5-oxaselenazines, have been synthesized stereoselectively by the reaction of selenoamides with aldehydes in the presence of boron trifluoride etherate complex.

EFFICIENT ENTRY TO THE STEROIDAL 14α-METHYL-8-ENE SYSTEM

Abstract: Treatment of 14α, 15α-epoxy-5α-cholestan-3β-ol trimethylacetate (1b) with boron trifluoride etherate in benzene gave the 8-en-15α-ol (2b) in 75% yield, which was then transformed, by oxidation, methylation and deoxygenation, into 14α-methyl-5α-cholest-8-en-3β-ol (7) 24, 25-Dihydrolanosterol (8) was also prepared by these procedures

Networks by fast epoxy polymerization

Abstract: A fast curing epoxy system, suitable for reactive processing, was investigated. The reaction of epoxy resin (Epon 815, Shell), comprising 85% diglycidyl ether of bisphenol-A and 15% butyl glycidyl ether with boron trifluoride etherate was extremely fast and uncontrollable at room temperature. The reaction rate could be controlled by complexing boron trifluoride with a polyether triol (Voranol 2070, Dow). The new system was ideal for reactive processing. It exhibited an induction time at an initial temperature of 40°C before undergoing very rapid curing. The induction time decreased from 55 to 2 seconds with increasing ratio of boron trifluoride to epoxy and with reactant temperature. The triol was fully incorporated in the network, affecting the final properties of the polymer network. Thus, it was possible to manipulate the gel times and material properties by varying the reactant ratios. A model system comprising phenyl glycidyl ether and octanol was used to investigate the mechanism. The incorporation of triol and the presence of cyclic oligomer indicates that both activated monomer and active chain end mechanisms were operating during the curing of these systems. The low molecular weights of the polymers made from the model system indicated the presence of chain transfer and termination reactions.

Process for the production of polybasic acid esters with recovery of boron trifluoride

Abstract: This invention provides a process for preparing an oligomer of at least one polyunsaturated aliphatic C12-22 monocarboxylic acid ester in the presence of boron trifluoride resulting in a high yield of predominantly trimeric product which, upon hydrolysis, affords a high yield or polybasic, predominantly trimeric, acids. This invention further provides such a process with excellent recovery of the boron trifluoride.

Reactions of Epoxides Derived From 2′-(3″-Methylbut-2″-enyl)trifluoroacetanilides

Abstract: The intramolecular nucleophilic ring opening of the epoxides derived from 2′-(3″-methylbut-2″-enyl) trifluoroacetanilides has been investigated under both acidic and basic conditions. Boron trifluoride caused rearrangement of the epoxides to a ketone but no cyclization. Potassium carbonate in methanol caused regiospecific opening of the epoxides and generated dihydroindole products. The formation of a five-membered ring was confirmed by a single-crystal X-ray study of one of the products. The epoxides hydrolysed very readily in acidic conditions; the structure of one of the diol products was confirmed by a single-crystal X-ray study.