Boron trifluoride ethyl ether complex

PVME was polymerized cationically with boron-trifluoride-ethyl ether complex as a catalyst the fraction with M = 1,690,000 was used for preparing the blends. PSD, with M > 4,000,000, was prepared by emulsion polymerization. 

Alternate Names boron trifluoride diethyl etherate boron trifluoride ethyl etherate boron trifluoride ethyl ether complex trifluoroboron diethyl etherate. 

In contrast, in the presence of boron trifluoride ethyl ether complex the potential of benzene oxidation was reduced less than with SbFs, in agreement with the fact that the interaction between the benzene and the etherate is weaker than with SbFs. The PPP films formed in this medium had a metallic aspect, were electroactive, homogeneous and adhered strongly to the electrode [142]. 

Preparation by reaction of 3,4-xylenol with benzoic acid in the presence of boron trifluoride-ethyl ether complex, at 128-129° for 7 min, followed by treatment of the difluoroboroxy chelate formed with boiling aqueous ethanol for 15 min (63%) [729]. 

Preparation by reaction of cyclohexene with 3,4-di-hydroxy-2, 5-dinitrobenzo-phenone in the presence of boron trifluoride ethyl ether complex for 12 h at reflux (24%). -Refer to Chem. Abstr., 127, 17465U (1997). 

In acid solution 1-acyl-1//-azepines and alkyl l//-azepine-l-carboxylates undergo rapid aromatization to A-arylcarbamates,115,139,142 whereas 1/Z-azepine-l-carbonitrile suffers quantitative rearrangement and hydrolysis to phenylurea.163 Rearrangement of ethyl l//-azepine-l-carboxylate to ethyl A-phenylcarbamate is also rapid (5 min) and quantitative with boron trifluoride-diethyl ether complex in benzene.245... 

Method A A solution of 0.5 mmol of (2/ /S ,3R/S )-2,3-dialkyl-1,4-diarylbutane and 0.125 mL (1.0 mmol) of boron trifluoride-diethyl ether complex in 2 mL of trifluoroacctic acid is added to a suspension of 0.12 g (0.26 mmol) of thallium(III) oxide in 2 mL of trifluoroacetic acid at — 40°C to +25CC under an argon atmosphere. The dark colored solution is stirred until the reaction is complete, diluted with ethyl acetate, then washed successively with water (twice) and sat. aq NaCl. Evaporation of the dried extract gives the crude product. In a variant of this method the boron trifluoride-diethyl ether complex can be omitted. 

Potential Lewis acidic species for this transformation are aluminum(III) chloride, ethyl-aluminum dichloride or methylaluminum sesquichloride. Reaction with this last reagent is found to occur less rapidly although the resulting yields of product are maximized. A number of common Lewis acids are unsuitable for this transformation, e.g., boron trifluoride diethyl ether complex, zinc chloride, and this may be attributed to preferential interaction of the Lewis acid with the allylstannane component. 

The pyridazinc moiety of ethyl l-ethyl-6-fluoro-4-oxo-7-(4-tolylsulfanyl)-l,4-dihydropyri-do[2,3-c]pyridazine-3-carboxylate can be reduced by the sodium borohydride/boron trifluoride-diethyl ether complex to give ethyl l-ethyl-6-fluoro-7-(4-tolylsulfanyl)-l,4-dihydropyrido [2,3-c]pyridazine-3-carboxylate.9... 

A solution of 3 g of the nitrile, water (5 moles per mole of nitrile), and 20 g of boron trifluoride-acetic acid complex is heated (mantle or oil bath) at 115-120° for 10 minutes. The solution is cooled in an ice bath with stirring and is carefully made alkaline by the slow addition of 6 A sodium hydroxide (about 100 ml). The mixture is then extracted three times with 100-ml portions of 1 1 ether-ethyl acetate, the extracts are dried over anhydrous sodium sulfate, and the solvent is evaporated on a rotary evaporator to yield the desired amide. The product may be recrystallized from water or aqueous methanol. Examples are given in Table 7.1. 

Intramolecular acylation has been used frequently. Houben-Hoesch cyclization of 1 -/ -cyanoethylpyrrole (2a) gives l-oxo-2,3-dihydropyrrolizine (3a).9-17 Difficulties occur because polymerization of the nitrile (2a) can be a side reaction. Addition of boron trifluoride [3a (33%)]11 or its ethyl ether complex [3a (60-80%)]15 has been recommended. Treatment of nitrile 2a with a molten aluminum chloride-potassium chloride-sodium chloride mixture yields 70% of ketone 3a but the experimental conditions are highly critical.13 A reproducible procedure that is based mainly on Clemo s specification9,10 gave 22% of ketone 3a.17 Purification of 3a should be carried out in an efficient fume hood because it appears to induce analgesia.1 ... 

Boron Trifluoride Ltherate. Boron fluoride ethyl ether boron fluoride etherate ethyl ether-boron trifluoride complex. C4HltBF30 mol wt 141.94. C 33.85%, H 7.10%, B 7.62%. F 40.16%, O 11.27%. (CH,CHj),O.BF,. Prepd by vapor-phase reaction of anhydr ether with BF, Lauben gayer, Finlay, J. Am. Chem. Soc. 65, 884 (1943). 

The synthesis of the representative compound of this series, 1,4-dihydro-l-ethyl-6-fluoro (or 6-H)-4-oxo-7-(piperazin-l-yl)thieno[2/,3/ 4,5]thieno[3,2-b]pyridine-3-carboxylic acid (81), follows the same procedure as that utilized for compound 76. Namely, the 3-thienylacrylic acid (77) reacts with thionyl chloride to form the thieno Sjthiophene -carboxyl chloride (78). Reaction of this compound with monomethyl malonate and n-butyllithium gives rise to the acetoacetate derivative (79). Transformation of compound 79 to the thieno[2 3f 4,5]thieno[3,2-b]pyhdone-3-carboxy ic acid derivative (80) proceeds in three steps in the same manner as that shown for compound 75 in Scheme 15. Complexation of compound 75 with boron trifluoride etherate, followed by reaction with piperazine and decomplexation, results in the formation of the target compound (81), as shown in Scheme 16. The 6-desfluoro derivative of 81 does not show antibacterial activity in vitro. 

Diethyl 7V-ethyl-A-[6-(4-ethoxycarbonyl-l-piperazinyl)-5-fluoro-2-pyri-dyl]aminomethylenemalonate (1027) was cyclized on the action of boron trifluoride etherate complex in diphenyl ether at 228-231 °C for 30 min to give the 1,8-naphthyridine derivative (1028) in 90% yield [84JAP(K)80683]. 

Ethylenedioxy-3(5,1 la.-dihydroxy-5a-pregnan-20-one.2 A solution of 3/ , 17a-dihydroxy-5a-pregnane-12,20-dione (8.75 g) dissolved in ethylene glycol (90 ml) containing boron trifluoride-ether complex (14 ml) is kept for 16 hr at room temperature. The solution is diluted with chloroform and washed to neutrality with water. The solution is evaporated to yield a crude ketal which is purified by crystallization from chloroform-ethyl acetate or methanol mp 255-259° (softens 252°) [a]D 74° (CHC13). 

Ethyl aluminum dichloride mediates a formal [5 + 2] cycloaddition of complex (164) and (166) with enol silyl ethers to produce the highly strained seven-membered rings (165) and (167) respectively (Schemes 239 -240). Excellent stereoselectivity is observed in both cases. A related double alkylation affords complexed seven-membered rings via a formal [4 - - 3] cycloaddition. Incorporation of fluorine is observed using boron trifluoride etherate (Scheme 241). 

From Table III it is apparent that a number of different donors could be used to obtain very attractive fractionation factors. Indeed, at 30°C., the isotopic equilibrium constant was 1.03, or more, for phenetole, anisole, diethyl ether, ethyl formate, dimethyl selenide, dimethyl sulfide, and diethyl sulfide. However, all of these donors were not equally satisfactory for our purpose. The boron trifluoride complexes of the thioethers, the selenide, and the ester had a pronounced tendency toward irreversible decomposition and were too unstable to be seriously considered for an... 

To a three-necked, round-bottomed flask fitted with two addition funnels and a reflux condenser connected to a gas buret was added 1.06 g boron trifluoride etherate (7.5 mmol), which was then cooled to — 15°C in an ice acetone bath. Then 5.0 mmol of the aromatic amine in a minimal volume of the anhydrous solvent (usually 10 mL) was added. If a solid of amine/BFs complex had formed, additional solvent or ethyl ether was added to produce homogeneous solution. tert-Buiyl nitrite (0.618 g. 6.0 mmol) in 5 mL of the same solvent was added drop wise to the rapidly stirred solution over a period of 10 min. After the complete addition, the temperature of the reaction was maintained at -15°C for 10 min and then allowed to warm to 5°C in an ice water bath over a 20-min period. A crystalline precipitate usually formed during the addition of tert-huiyl nitrite, and after 20 min at 5°C, precipitation was complete. Pentane (40 mL) was then added to the reaction solution, and the solid was suction filtered, washed with cold ether, air dried, and weighed. 

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