Boron trialkyls etherate

The synthesis of triorganoboron compounds by means of zinc alkyls was first achieved by Frankland. A similar procedure using Grignard reagents and boron trifluoride etherate has been used lor a number of trialkyl- [12] and arylboron compounds [13] (eq(lO) and (11)). 

Polymerization by Ionic Catalysts. Attempts to polymerize monomer I with ionic catalysts such as trimethylphosphite or boron trifluoride-etherate at room temperature did not succeed. No reaction was visible in either case despite the fact that it has been reported that trialkyl phosphites react vigorously with sulfur at room temperature (21). However, even in that specific instance, no polymerization was observed. The use of an anionic initiator such as n-butyllithium did not produce polymer either. In this case, however, a reaction did occur, as evidenced by the discoloration of the monomer solution. 

N-Alkylation of anthranils has been achieved using r-butyl alcohol in 60% perchloric acid,233,234 methyl fluorosulfonate,235 dimethyl sulfate,236 triethyloxonium tetrafluoroborate,237 and, unusually, trialkyl orthoformates in the presence of boron trifluoride etherate.237 Rate studies for the N-methylation of anthranils in dimethyl sulfate are available.36... 

Alkyl ethers of dialkyl (hydroxymethyl)phosphonic acid have been obtained by a modified Arbuzov procedure in the presence of BF3 Et20, triethyl phosphite reacts with the formals ROCH20Ar according to Scheme 16 the reactions are best carried out in the presence of TiCl4 at -78 °C, but the Lewis acid catalyst and the experimental conditions have to be chosen carefully, otherwise mixed alkyl aryl esters are produced. Boron trifluoride etherate also catalyses the interaction of acetals of 4-substituted benzaldehydes with triethyl phosphite to give diethyl (a-alkoxybenzyl)phosphonates. Both aliphatic and aromatic aldehydes are reported to react with trialkyl phosphites at 100 °C to give the ethers 204 ... 

Low-molar-mass poly(butadiene) oils with 80%-97% cw-1,4 contents are produced with other Ziegler catalysts (for example, cobalt compounds with alkyl aluminum chlorides or nickel compounds with trialkyl aluminum and boron trifluoride-etherate). The products have few cross-links and dry as fast as wood oil and faster than linseed oil. Conversion of the poly (butadiene) oils with 20% maleic anhydride gives air-drying (air-hardening) alkyd resins. Modified poly (butadiene) oils stabilize erosion-endangered soils. Because of its low viscosity, the aqueous emulsion penetrates the surface soil layers. The surface crust is reinforced by an oxidative bonding process. Since no skin is formed on the soil crust, the aqueous absorption characteristics of the soil are retained. 

Alkylation of 2,1-benzisothiazoles (102) with trialkyl orthoformates in the presence of Lewis acids such as boron trifluoride etherate affords the quaternary salts (103). Their treatment with secondary amines produces the expected 1 -alky 1-3-aryl-3-dialkylamino-2,1 -benzisothiazoline derivatives (104). In contrast, the presumed intermediates (105) arising from primary amines (including glycine methyl ester) are cleaved, with extrusion of sulphur, to the azomethines (106). ... 

Lewis acids, particularly the boron trifluroride diethyl ether complex, are used to promote the reaction between allyl(trialkyl)- and allyl(triaryl)stannanes and aldehydes and ketones52-54. The mechanism of these Lewis acid promoted reactions may involve coordination of the Lewis acid to the carbonyl compound so increasing its reactivity towards nucleophilic attack, or in situ transmetalation of the allyl(trialkyl)stannane by the Lewis acid to generate a more reactive allylmetal reagent. Which pathway operates in any particular case depends on the order of mixing of the reagents, the Lewis acid, temperature, solvent etc.55- 58. 

The stereoselectivity of Lewis acid promoted reactions between 2-butenylstannanes and aldehydes has been widely studied, and several very useful procedures for stereoselective synthesis have been developed. In particular syn-products are formed stereoselectively in reactions between trialkyl- and triaryl(2-butenyl)stannanes, and aldehydes induced by boron trifluoride-diethyl ether complex, irrespective of the stannane geometry66. 

The base-induced reaction of dichloromethyl methyl ether with trialkyl- and triarylboranes also provides a powerful method for the preparation of the corresponding tertiary carbinols.16,17 In this case, all three groups transfer readily from boron to carbon under mild conditions, and oxidation with alkaline hydrogen peroxide provides the tertiary alcohol ... 

Trialkyl- and triaryl-borons have often been prepared from a boron halide or boric ester by means of a more reactive organometallic compound, usually a Grignard reagent. The halide that is most convenient in use is boron trifluoride as its stable etherate 207... 

The polymerization o oxetanes with cationic catalysts has been studied by many investigators. (1.H2) RoseC. ), in particular, first reported the homopolymerization of the parent compound, tri-methylene oxide (TMO), with a Lewis acid catalyst, boron trifluoride. The use of coordination catalysts to polymerize oxetanes has been reported in the patent literature by Vandenberg.W In this work, Vandenberg polymerized oxetanes with the aluminum trialkyl -water-acetylacetone coordination catalyst (referred to as chelate catalyst) that he discovered for epoxide polymerization . This paper describes the homo- and co-polymerization of TMO with these coordination catalysts. Specific TMO copolymers, particularly with unsaturated epoxides such as allyl glycidyl ether (AGE), are shown to provide the basis for a new family o polyether elastomers. These new elastomers are compared with the related propylene oxide-allyl glycidyl ether (PO-AGE) copolymer elastomers. The historical development and general characteristics of polyether elastomers and, in particular, the propylene oxide elastomers, are reviewed below. 

Enol stannanes of cyclohexanone and propiophenone have been indicated to take part in r/treo-selective aldol reactions with benzaldehyde at low temperatures e.g. —78 °C), but to be erythro-seAsciiwe at higher temperatures ca 45 °C). Two complementary methods have been described for stereoselection in aldol-type reactions. Whilst a-mercurio-ketones show eryr/wo-selection in their reactions with aldehydes in the presence of boron trifluoride diethyl etherate, pre-formed lithium enolates and aldehydes, in the presence of simple trialkyl-boranes, lead to mixtures that are rich in the more stable threo-d do product. Aldol-type products arise from 1,3-alkyl migrations of alk-l-enyl alkyl acetals and ketals, in a reaction that is catalysed by boron trifluoride diethyl etherate (Scheme 52). Diastereoselection is possible, since (.E)-alkenyl acetals give the... 

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