Synthesis of bi- and tricyclic acrylates in the presence of boron trifluoride etherate

The addition of acrylic acid to bicyclo[2.2.1]heptene hydrocarbons and tricyclo[5.2.1.0^2,6]deca-3,8-diene catalyzed with BF₃·O(C₂H₅)₂ was studied and bi- and tricyclic esters of acrylic acid were synthesized that were reactive monomers for preparation of macromolecular compounds.     

Pechmann reaction promoted by boron trifluoride dihydrate

The Pechmann reaction of substituted phenols 1a-e with methyl acetoacetate (2) can be activated by boron trifluoride dihydrate (3) to give the corresponding 4-methyl- coumarin derivatives 4a-e in excellent yield (98-99 %).     

Stereochemical course of the hydrogen migration in the boron trifluoride etherate-catalyzed rearrangement of 1,1-disubstituted epoxides

Mechanistic studies on the BF₃·Et₂O-catalyzed rearrangement of optically active, regioselectively deuterated 1,1-disubstituted epoxides to aldehydic products revealed that the two hydrogens migrate at the migration terminus with opposite stereochemical preferences, i.e. the hydrogen anti to the bulky substituent prefers to migrate with inversion of configuration, whereas the hydrogen syn to the bulky substituent prefers to migrate with retention of configuration.     

Study of the reaction between boron trifluoride methanol complex and sodium methoxide

The reaction between boron trifluoride methanol complex and sodium methoxide in methanol solution was investigated using conductivity as the reaction indicator. The reaction conditions were examined and a mechanism of this reaction was proposed. Moreover, proper reaction conditions were proposed for boric acid preparation using this reaction.     

Novel deoxygenation reaction of epoxides by indium

[reaction: see text] A novel, mild, ecofriendly protocol for the deoxygenation of epoxides to alkenes using indium metal and indium(I) chloride or ammonium chloride in alcohol has been developed. It was necessary for the presence of good radical-stabilizing groups adjacent to the oxirane ring for the deoxygenation reaction to occur. It is proposed that this reaction occurs through an SET process with indium as an electron donor.     

A ring opening reaction of oxetanes with lithium acetylides promoted by boron trifluoride etherate

Several substituted oxetanes were treated with lithium acetylides in the presence of boron trifluoride etherate to give f-hydroxyacetylenes. The reaction conditions were varied and several synthetic features of the present reaction were revealed.     

Donor-acceptor complexes of quinoline N-oxides with boron trifluoride

Molecular n-v complexes of quinoline N-oxides with BF₃ have been studied by electronic and IR spectroscopy. In most case the donor centre is the oxygen atom of the N-oxide group.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1087–1092, August, 1994.     

The electronic structure of boron trifluoride

The electronic structure of boron trifluoride has been calculated ab initio by using extended basis sets of Gaussian type atomic orbitals. By variation of the B-F bond length a minimum energy situation was found at 1.306 å (experimental 1.31 å). Calculations on the pyramidal (reorganised) form of the molecule led to a reorganisation energy of 34.2 kcal mole^–1. The localisation energy was found to be 50.4 kcalmole^–1. Both the latter energy and the charge distribution are in good agreement with results from a previous Pariser-Parr-Pople calculation. The calculated quantities are used to discuss the energetics of donor-acceptor complex formation.

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Zusammenfassung Die Elektronenstruktur des BF₃-Moleküls wird mit Hilfe einer ab initio Rechnung unter Verwendung einer erweiterten GTO-Funktionsbasis ermittelt. Die Variation der Energie bezüglich des B-F-Bindungsabstandes führt zu einem Energieminimum für einen B-F-Abstand von 1,306 å in guter übereinstimmung mit dem Experiment (1,31 å). Dabei erweist sich das planare BF₃-Molekül gegenüber dem pyramidalen um 34,2 Kcal/Mol stabiler. Die -Elektronen-Lokalisierungsenergie betrÄgt 50,4 Kcal/Mol. Bezüglich dieser Energie sowie der -Elektronenladungsverteilung ergibt sich gute übereinstimmung mit den Resultaten vorangegangener PPP-Rechnungen. Die berechneten Grö\en werden zur Diskussion der VorgÄnge in Donor-Akzeptor-Komplexen herangezogen.

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Résumé Calcul ab initio de la structure électronique due trifluorure de Bore en base étendue d'orbitales atomiques Gaussiennes. La variation des longueurs des liaisons BF donne un minimum à 1.306 å (valeur expérimentale 1.31 å). Les calculs de la forme pyramidale (réorganisée) de la molécule donnent une énergie de réorganisation de 34.2 kcal/mole. L'énergie de localisation vaut 50.4 kcal/mole. Cette dernière valeur, et la distribution de la charge sont en bon accord avec les résultats d'un calcul antérieur dans le approximations de Pariser-Parr-Pople. Les quantités calculées sont utilisées dans une discussion des caractéristiques énergétiques de la formation de complexes donneur-accepteur.

     

Crystallization during polymerization of diazomethane. I. The boron trifluoride catalyzed reaction

The polymerization and crystallization of diazomethane was analyzed starting with various monomer and catalyst concentrations by following the monomer concentration and analysis of the solid polymethylene produced. Electron microscopy, thermal analysis, x-ray diffraction, and viscometry and density determinations were used to characterize the crystals as produced and after etching with nitric acid. The crystals have a fibrillar and a lamellar component and show no regular chain folding of the molecules. The overall process follows only very approximately the path expected for an ideal living-polymer system capable of reaction in solution and in the solid state. For more detailed correspondence, it was necessary to assume two reaction paths and two crystallization paths.     

Anionotropic shift of the 3-substituent in the reaction of 2-methoxy-2,3-dihydro-3-benzofuranols with boron trifluoride

The reaction of 2,3-dihydro-3-benzofuranols 1a,c,d,f with boron trifluoride in boiling xylene gave 3-(2H)benzofuranones 2a,c,d,f in 40-85% yield. This reaction was not observed in the case of 1b,e.     

Polyvinylpolypyrrolidone-supported boron trifluoride: a high-loaded, polymer-supported Lewis acid for the Ritter reaction

Abstract  

A Mild and efficient method for preparing amides by reaction of nitriles with benzhydrol and tertiary alcohols is described using polyvinylpolypyrrolidone-supported boron trifluoride. Selective amidation of benzhydrol in the presence of primary benzyl alcohols was also achieved.     

Polyvinylpolypyrrolidone-supported boron trifluoride: a high-loaded,polymer-supported Lewis acid for the Ritter reaction

Abstract  A Mild and efficient method for preparing amides by reaction of nitriles with benzhydrol and tertiary alcohols is described using polyvinylpolypyrrolidone-supported boron trifluoride. Selective amidation of benzhydrol in the presence of primary benzyl alcohols was also achieved. Graphical abstract        

Studies of acenaphthene derivatives—XXVIII : The reaction of 2-diazoacenaphthenone with anils in the presence of boron trifluoride

Reaction of 2-diazoacenaphthenone with anils in the presence of a catalytic amount of boron trifluoride etherate is reported. The diazoketone reacts with benzylidenanilines to afford a mixture of stereoisomers of spiro[acenaphthenone-2′,4-imidazolidine], whose structures correspond to compounds derived from 1:2 adducts of the diazoketone and anils with the elimination of nitrogen. A pathway involving spiro-aziridine intermediates is proposed for their formation. Reaction of the diazoketone with aα-alkylbenzylidenanilines however gives the corresponding acenaphtho[1,2-b]pyrroles, whose structures correspond to compounds arising from 1:1 adducts with the elimination of both nitrogen and water. The reaction of the tautomeric enamine form of the anil with a carbenoid intermediate generated from the diazoketone is suggested for pyrrole formation.     

Large gas-solid structural differences in complexes of haloacetonitriles with boron trifluoride

The structural properties of the singly halogenated derivatives of CH(3)CN-BF(3) (X-CH(2)CN-BF(3): X = F, Cl, Br, I) have been investigated via single-crystal X-ray crystallography, solid-state infrared spectroscopy, and correlated electronic-structure theory. Taken together, these data illustrate large differences between the gas-phase and solid-state structures of these systems. Calculated gas-phase structures (B3PW91/aug-cc-pVTZ) of FCH(2)CN-BF(3), ClCH(2)CN-BF(3), and BrCH(2)CN-BF(3) indicate that the B-N dative bonds in these systems are quite weak, with distances of 2.422, 2.374, and 2.341 A, respectively. However, these distances, as well as other calculated structural parameters and normal-mode vibrational frequencies, indicate that the dative interactions do become slightly stronger in proceeding from F- to Br-CH(2)CN-BF(3). In contrast, solid-state structures for FCH(2)CN-BF(3), ClCH(2)CN-BF(3), and ICH(2)CN-BF(3) from X-ray crystallography all have B-N distances that are quite short, about 1.65 A. Thus, the B-N distances of the F- and Cl-containing derivatives contract by over 0.7 A upon crystallization. Large shifts in the vibrational modes involving motions of the BF(3) subunit parallel these structural changes. An X-ray crystal structure could not be determined for BrCH(2)CN-BF(3)(s), but the solid-state IR spectrum is consistent with those obtained previously for related complexes and suggests that the solid-state structure resembles those of the others, and in turn, implicates a large gas-solid structural difference for this species as well.     

Catalysis of olefin isomerizations by boron trifluoride

The kinetics of isomerization of butenes by boron trifluoride with acetic acid or methanol as cocatalysts have been re-examined. The results, over a wide concentration range, and at temperatures from ?20 to +20°C, are consistent with previous data, but it is shown that the previously suggested mechanism cannot apply. By using deuterated acetic acid as cocatalyst it has been found that isomerization exactly parallels protonation, which is consistent with a mechanism involving a classical carbonium ion.     

Reaction of methyl hypochlorite with certain olefins in the presence of boron trifluoride

Fluoro chlorides are major products in the reaction of methyl hypochlorite with certain olefins in the presence of boron trifluoride.     

Thermal stability of epoxy compounds cured with boron trifluoride complexes

The thermal resistances of epoxy resins cured with complexes of boron trifluoride with benzylamine, 2-benzylaminoethanol and 2-anilinoethanol were examined. Thermal analysis data were used to compare the thermal resistances of epoxy compusitions cured with polyamines (aliphatic and aromatic), acid anhydrides and complexes of boron trifluoride with the above amines.

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Zusammenfassung Der WÄrmewiderstand von mit Komplexen von Bortrifluorid mit Benzylamin, 2-Benzylamino-Äthanol und 2-Anilino-Äthanol gehÄrteten Epoxyharzen wurde untersucht. Anhand thermoanalytischer Daten wurden die WÄrmewiderstandswerte von mit (aliphatischen und aromatischen) Polyaminen, SÄureanhydriden und Komplexen von Bortrifluorid mit den oben angeführten Aminen gehÄrteten Epoxy-Kompositionen miteinander verglichen.

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