Boron trifluoride etherate catalyst

Polyepichlorohydrin and dimethylamine Polymerisation of epichlorohydrin in carbon tetrachloride with boron trifluoride/ether catalyst, then reaction with dimethylamine. Applied to cotton by exhaust method or pad-dry. Scheme 10.65 Good yields with direct dyes using only 2 g/l salt. Excellent build-up with most reactive dyes only 10% of normal salt usage needed for low-reactivity dyes and none for highly reactive types. Washing fastness very good but light fastness impaired. 

Radiation-induced polymerization of crystalline tetroxocane gives a highly crystalline linear polymer in essentially 100% yield (63MI51900,68MI51901), and this has attracted some industrial attention. Tetroxocane also gives a crystalline polymer very rapidly under cationic conditions (boron trifluoride etherate catalyst) and the kinetics of the process have been studied <76MI51900>. 

Indolizines with a saturated six-membered ring may be obtained from pyrrole or furan derivatives.225,226 The reaction of 3,4-dimethylpyrryl-magnesium bromide with y-chlorobutyronitrile followed by dilute acid gave 5,6,7,8-tetrahydro-l,2-dimethyl-5-oxoindolizine. 5,6,7,8-Tetrahy-droindolizine can be obtained by the cyclodehydration of 3-(2-furyl)-propylamine over alumina at 400°C. The same product is obtained by the treatment of 3-(2-pyrryl)propyl cyanide with hydrogen chloride in the presence of boron trifluoride etherate catalyst, followed by Wolff-Kishner reduction of the intermediate ketone. 

Tris[3-tert-butyl-4-(hydroxybenzyl)]mesitylene (III) was synthesized starting from 2-fert-butyl-6-chlorophenol, which in turn was prepared by the method of Kolka et al. (10). The 2-ferf-Butyl-6-chlorophe-nol was alkylated with a1,a3,a5-(trihydroxyhexamethyl)benzene (Aldrich) with the use of boron trifluoride etherate catalyst (II). A mixture of I and II was obtained, separated by fractional crystallization from methyl-cyclohexane. The structures of the two products were assigned on the... 

Reactions with boron trifluoride etherate catalyst at... 

In 1948 the structure of the crystalline polymer was not known. Later, Natta et al. (1955a) showed that it was isotactic. Evidently the methyl derivative also afforded crystalline isotactic polymer, but the ethyl, isopropyl, and %-butyl derivatives gave less ordered macromolecules with boron trifluoride-ether catalyst in propane (Schildknecht et al., 1949). 

Preparation of Poly(vinyl n-butyl ether) Using Boron Trifluoride Etherate Catalyst [28]... 

Boron Trifluoride Etherate Catalyst — - — - E - — in phenol and water during alkylation. Alloy C = 0.2 mpy (vapor). <0.1 mpy (bqmd)... 

Most of the compounds in this class have been prepared from preexisting crown ether units. By far, the most common approach is to use a benzo-substituted crown and an electrophilic condensation polymerization. A patent issued to Takekoshi, Scotia and Webb (General Electric) in 1974 which covered the formation of glyoxal and chloral type copolymers with dibenzo-18-crown-6. The latter were prepared by stirring the crown with an equivalent of chloral in chloroform solution. Boron trifluoride was catalyst in this reaction. The polymer which resulted was obtained in about 95% yield. The reaction is illustrated in Eq. (6.22). 

The dimethyl acetal (94) is readily prepared from the 22-aldehyde (93) by direct reaction with methanol in the presence of hydrogen chloride. Ena-mines (95) are formed without a catalyst even with the poorly reactive piperidine and morpholine.Enol acetates (96) are prepared by refluxing with acetic anhydride-sodium acetate or by exchange with isopropenyl acetate in pyridine.Reaction with acetic anhydride catalyzed by boron trifluoride-etherate or perchloric acid gives the aldehyde diacetate. 

Boron trifluoride etherate in benzene converts A -20-acetoximinosteroids to the 17-ketones in somewhat lower yield, but the reaction of A -20-oximino steroids with this catalyst in the presence of acetic anhydride does not give the expected product two different compounds have been isolated and identified. ... 

A direct method for introduction of a C-21 acetoxyl group into a 20-keto-pregnane is by reaction with lead tetraacetate at room temperature. Although originally the reaction carried out in hot acetic acid gave low yields, a careful study by Henbest has defined conditions so that yields as high as 86 % can be obtained at room temperature. The preferred solvent is 5 % methanol in benzene, with boron trifluoride etherate as catalyst. With either methanol or benzene, the yield is less than 4%. 

Covalent fluondes of group 3 and group 5 elements (boron, tin, phosphorus, antimony, etc ) are widely used m organic synthesis as strong Lewis acids Boron trifluoride etherate is one of the most common reagents used to catalyze many organic reactions. A representative example is its recent application as a catalyst in the cycloadditions of 2-aza-l,3-dienes with different dienophiles [14] Boron trifluoride etherate and other fluonnated Lewis acids are effective activators of the... 

Boron trifluoride etherate, is also a good catalyst for this hydride transfer to chalcone. Unlike triphenylmethyl perchlorate, however, chalcone is able to enter Michael additions with the 1,5-diketone followed by eliminations leading to unexpected products, e.g., 3-benzyl-2,4,6-triphenylpyrylium from 2-carbethoxy-l,3,5-tri-phenylpentane-l,5-dione and chalcone the benzyl group originates from chalcone, the elimination product being ethyl benzoylacetate. ... 

The same general procedure as in the preceding case is employed. In place of the anhydrous aluminum chloride, boron trifluoride etherate (2 drops, approx. 0.8 mmole) is employed as the catalyst. The reaction technique and work-up are the same. 

RCM was also used in Yamamoto s total synthesis of the marine neurotoxin gambierol (81) [62], to close the central seven-membered E ring, thereby completing the octacyclic polyether core 80 (Scheme 15). Following previously developed methodology [63], metathesis precursor 79 was produced as the major epimer, by boron trifluoride etherate-mediated intramolecular allylation of a-chloroacetoxy ether 78. Subsequent treatment of 79 with catalyst C produced the octacyclic ether 80 in 88% yield. 

The role of Lewis acids in the formation of oxazoles from diazocarbonyl compounds and nitriles has primarily been studied independently by two groups. Doyle et al. first reported the use of aluminium(III) chloride as a catalyst for the decomposition of diazoketones.<78TL2247> In a more detailed study, a range of Lewis acids was screened for catalytic activity, using diazoacetophenone la and acetonitrile as the test reaction.<80JOC3657> Of the catalysts employed, boron trifluoride etherate was found to be the catalyst of choice, due to the low yield of the 1-halogenated side-product 17 (X = Cl or F) compared to 2-methyI-5-phenyloxazole 18. Unfortunately, it was found that in the case of boron trifluoride etherate, the nitrile had to be used in a ten-fold excess, however the use of antimony(V) fluoride allowed the use of the nitrile in only a three fold excess (Table 1). 

With boron trifluoride etherate instead of trimethylsilyl triflate the yield was 51%, without catalyst 40% and without catalyst and HMPA 25%.t88],[89] With CH3MgI instead of CH3MgBr the ketone is further transformed into a tertiary alcohol.[893 b) Reaction in the presence of FeCl3.[90J... 

Boron trifluoride etherate, co-catalyst, 53, 30, 32 a-Bromination, selective of aralkyl ketone, 53, 111 Bromine, with 3-chlorocyclo-butanecarboxylic acid and mercuric oxide to give 1-bromo-3-chlorocyclobutane, 51, 106... 

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