Preparation triethylborane

This derivative is stable to acetic acid and CF3C02H. The related diethylborinic acid derivative has been prepared from triethylborane (THF, reflux). ... 

Ishikura and co-workers (95H2437) have extended the scope of this reaction, combining our results with their borate chemistry. Thus, the reaction of 2-lithio-l-methoxyindole (72), prepared from 1-methoxyindole (71) and -BuLi (92H1285, 92H1295, 94H31), with triethylborane generates an indolylborate 73 in situ (Scheme 11). Subsequent treatment of 73 with aqueous NaOH and 30%... 

The anti diastereoselectivity is improved to a 6 1 ratio by the addition of triethylborane to the reaction mixture83. NMR-spectroscopic investigations indicate that a boronate complex is the decisive intermediate84, since it can also be prepared by the addition of alkyllithium to the dialkyl(2-butenyl)borane (path ). 

The /3-trimethyltin-substituted alkenylborane 36 was prepared in situ by treatment of triethylborane with 1-lithio-l-hexyne to form the lithium 1-alkynyltriethyl-borate 35 followed by trimethyltin chloride (Scheme 20.9) [37]. The trimethyltin chloride-induced migration of an ethyl group from boron to the adjacent acetylenic carbon is stereoselective with the boron and the tin substituents in 36 cis to each... 

This methodology was applied to a two-step sequence for the preparation of enantio-merically enriched dihydrobenzo[h]furans (Scheme 10.11) [46]. Rhodium-catalyzed allylic etherification of (S)-47 (>99% ee), with the sodium anion of 2-iodo-6-methyl-phenol, furnished the corresponding aryl allyl ethers (S)-48/49 as a 28 1 mixture of regioisomers favoring (S)-48 (92% cee). Treatment of the aryl iodide (S)-48 with tris(trimethylsilyl)silane and triethylborane furnished the dihydrobenzo[h]furan derivatives 50a/50b as a 29 1 mixture of diastereomers [43]. 

Methylene chromans can be prepared by a palladium-catalyzed intramolecular cyclization of 2-iodophenyl alkynyl ethers 455. Simple modifications to the reaction conditions lead to either (E)- or (Z)-4-methylene chromans (Scheme 103) <2001TL2657>. 2-Iodophenyl alkynyl acetals are also viable substrates for this reaction <2005JOG489>. Addition of tris(2,6-diphenylbenzyl)tin hydride (TDTH) to a triethylborane-mediated intramolecular cyclization of 2-iodophenyl alkynyl ethers ensures complete (A)-selectivity is observed in the resulting 4-methylene chroman <2001AGE411>. 

Charge ( )-1-(triisopropylsiloxy)-1,3-butadiene into the reaction vessel, then add diethylborane, prepared from triethylborane and borane-methyl sulfide complex, at 0°C over 10 min. 

The alkenylation reaction of ct-halo carbonyl compounds with alkenylindium in the presence of triethylborane proceeds via a radical process. Unactivated alkene moieties as well as a styryl group can be introduced by this method. The geometry of the carbon-carbon double bonds of the alkenylindium is retained. Preparation of alkenylindium via hydroindation of 1-alkyne followed by the radical alkenylation establishes an efficient one-pot strategy (Scheme 113).384... 

Calcium bis[tetrahydroborate(l-)] may be prepared from sodium tetra-hydroborate( 1 -) and calcium dichloride by cation exchange11 in a suitable solvent such as dimethylformamide,12 an amine13,14 or an alcohol.13,14 A particularly good preparation of very pure Ca[BH4]2 involves the reaction of calcium dihydride with the triethylamine-borane adduct.15,16 This method may also be used for the preparation of other tetrahydroborates of alkali and alkaline earth metals. The triethylamine-borane adduct17 may be synthesized in a variety of ways, e.g., from triethylamine, sodium tetrahydro-borate(l —), and trichloroborane 18 from a trialkoxyborane, aluminum metal, and hydrogen in the presence of triethylamine 19 or by hydrogenation under pressure of a mixture of triethylborane and triethylamine.20 The triethylamine-borane adduct is a colorless liquid (mp — 2°). It is stable to air and moisture at room temperature and it is easily purified by vacuum distillation (bp 95-96°/12 torr). 

One-pot synthesis of ( )-alkenes has been directly performed from nitromethane by a radical process (Liu and Yao, 2001). In fact, the strategy is to react P-nitrostirene (3) as shown in Figure 2.1, in situ prepared from aromatic aldehydes (1) with nitromethane (2) in the acetic acid solution with a catalytic amount of ammonium acetate at 70-100°C, with triethylborane in the biphase of diethyl ether and aqueous solution in the presence of oxygen in air as radical initiator, to generate (4). 

An initiator system consisting of triethylborane and hexamethylenediamine was prepared by Deviny [4] and used in adhesives. 

The use of sulfur dioxide as the solvent and low temperatures allows efficient and clean formation of the a-chloro nitroso compound4 6. The primary adducts, containing nitroso, nitro, or oxime functions, can be reduced to chlorine-free amines or /i-chloro amines 8. Additionally, chlorine readily undergoes substitution by nucleophiles (hydrides, alcohols, amines, etc.), such that halogen-free and /i-functionalized nitroso and nitro compounds, which can further be reduced to amines, can be prepared by this route. Recently, the conversion of nitroso compounds (RNO) to amines (RNHEt) using a triethylborane/borane mixture has been described9 10, although not applied specifically to /i-chloro nitroso compounds. 

Bicyclic ketones are prepared by cycloadditions of methylenecyclopropanes with cyclic a,P-unsatu-rated carbonyl compounds. c J-Bicyclo[3.3.0]octan-2-ones (50), (51) and (52) are obtained in good yields by phosphine-nickel(0)-catalyzed cross coupling reactions of 2-cyclopentenone with methylenecyclopropanes in the presence of 0.1-1 equiv. of triethylborane as a Lewis acid (equations 18 and 19 and... 

The reagent is prepared in THF solution by the reaction of lithium hydride (2, 251) with triethylborane. It is stable indefinitely. 

This reagent is conveniently prepared by the reaction of triethylborane with lithium hydride in THF. The THF solution (1.0 M) is commercially available from Aldrich under the name of Super-Hydride . 

Radical addition of triphenylgermane to vinyl oxiranes proceeded in the presence of triethylborane to yield 4-triphenylgermyl-2-buten-l-ol derivatives in good yield. Iodo acetals, prepared by iodoetherification of vinyl ethers with the allylic alcohol, underwent radical cychzation to give 2-alkoxy-4-vinyltetrahydrofurans which were converted into 4-vinyltetrahydro-2-furanones by Jones oxidation (Scheme 11.22) [38]. 

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