Boron fluoride synthesis

Boron fluoride Synthesis of ) -alkoxyacetals from enolethers... 

Organolithium compels. I boron fluoride Synthesis of alkoxyiamines from aldoximes... 

The structure of baogongteng A was further confirmed by total synthesis by Xiang et al. [43]. 6(3-acetoxy-tropinone 6-4 was used as starting material for the synthesis. It was through bromination with liquid bromine in acetic acid, hydrolyzation with silver carbonate, and ketalization in thioglycol and adding boron fluoride dihydrate in ethyl ether solution to... 

Boron Bromide. One hundred thirty-three and one-half grams of aluminum bromide (0.5 mol) (synthesis 7) is distilled into the reaction flask and treated with boron fluoride as described for boron chloride. It is desirable to reflux the aluminum bromide gently in the stream of boron fluoride. The contents of the flask soon solidify. When this happens the mass is heated strongly in boron fluoride to distill all of the produfct over into the U-tube where it is condensed. Small amoimts of bromine in the product are readily removed by shaking with mercury. Yield, 87.7 g. (70 per cent). This product is satisfactory for most purposes, but may be redistilled through a good column to effect further purification. 

Stability. Another major facet in the overall performance of electrochromic materials is the stability of the system. Many potential issues, such as degradation of the active redox couple due to irreversible oxidation or reduction at extreme potentials, iR loss of the electrode or the electrolyte, detrimental side reactions due to the presence of water or oxygen in the cell or heat release due to the resistive parts in the system, can result in the eventual loss of electrochromic contrast and function [7]. One effective approach towards the improvement of electrochemical cycling stability is the use of boron fluoride ethyl ether (REEF.) during the electrochemical synthesis of some heterocyclic compounds (including thiophene and bithiophene) [20]. For example, Camurlu et al. have shown reasonable stability and a switching speed of less than 1.5 s for the homopolymer of hexanedioic acid bis (2-thiophen-3-ylethyl) ester (HABTE) [21],... 

Example 5 Polyaniline-Boronic Acid - Synthesis of Poly(aniline-co-3-amino-phenylboronic Acid)-without Fluoride (5a)... 

Boron fluoride/sodium tetrahydridoborate Alcohols from ethylene derivatives Asym. synthesis... 

Continuous-Flow Stirred-Tank Reactors. The synthesis of j )-tolualdehyde from toluene and carbon monoxide has been carried out using CSTR equipment (81). -Tolualdehyde (PTAL) is an intermediate in the manufacture of terephthabc acid. Hydrogen fluoride—boron trifluoride catalyzes the carbonylation of toluene to PTAL. In the industrial process, separate stirred tanks are used for each process step. Toluene and recycle HF and BF ... 

Table 3. Synthesis of ort/io-Substituted Fluoroaromatics from Nitrite Esters, Boron Trifluoride, and Hydrogen Fluoride [26]...

Mesitaldehyde may be prepared from mesitylmagnesium bromide by the reaction with orthoformate esters3 or ethoxy-methyleneaniline 3 from acetylmesitylene by oxidation with potassium permanganate,4 from mesitoyl chloride by reduction,5 from mesityllithium by the reaction with iron pentacarbonyl and from mesitylene by treatment with formyl fluoride and boron trifluoride,7 by treatment with carbon monoxide, hydrogen chloride, and aluminum chloride,8 or by various applications of the Gatterman synthesis.9-11... 

Notable examples of general synthetic procedures in Volume 47 include the synthesis of aromatic aldehydes (from dichloro-methyl methyl ether), aliphatic aldehydes (from alkyl halides and trimethylamine oxide and by oxidation of alcohols using dimethyl sulfoxide, dicyclohexylcarbodiimide, and pyridinum trifluoro-acetate the latter method is particularly useful since the conditions are so mild), carbethoxycycloalkanones (from sodium hydride, diethyl carbonate, and the cycloalkanone), m-dialkylbenzenes (from the />-isomer by isomerization with hydrogen fluoride and boron trifluoride), and the deamination of amines (by conversion to the nitrosoamide and thermolysis to the ester). Other general methods are represented by the synthesis of 1 J-difluoroolefins (from sodium chlorodifluoroacetate, triphenyl phosphine, and an aldehyde or ketone), the nitration of aromatic rings (with ni-tronium tetrafluoroborate), the reductive methylation of aromatic nitro compounds (with formaldehyde and hydrogen), the synthesis of dialkyl ketones (from carboxylic acids and iron powder), and the preparation of 1-substituted cyclopropanols (from the condensation of a 1,3-dichloro-2-propanol derivative and ethyl-... 

Boron trihalides are strong Lewis acids that react with a wide collection of Lewis bases. Many adducts form with donor atoms from Group 15 (N, P, As) or Group 16 (O, S). Metal fluorides transfer F ion to BF3 to give tetrafluoroborate salts LiF + BF3 LiBF4 Tetrafluoroborate anion is an important derivative of BF3 because it is nonreactive. With four <7 bonds, [BF4 ] anion has no tendency to coordinate further ligands. Tetrafluoroborate salts are used in synthesis when a bulky inert anion is necessary. 

Takahashi and coworkers described the one-pot synthesis of core 2 branched oligosaccharides [236], It was found that boron trifluoride complexed with a tri-methylsilyl ether would enhance the nucleophilidty of the silyl ether. As a result, glycosylations of the 6-O-TMS modified acceptor with a glycosyl fluoride provided... 

A convenient method for the preparation of nitronium tetrafluoroborate involves treating a mixture of absolute nitric acid or an alkyl nitrate " with anhydrous hydrogen fluoride and an excess of boron trifluoride. Pure nitronium triflate can be synthesized by treating triflic anhydride or triflic acid with dinitrogen pentoxide in an inert solvent. Other methods for nitronium salt synthesis are discussed by Olah. ... 

A novel method for the convenient synthesis of alkenyl fluorides 15, as well as diflu-oromethyl-substituted alcohols 16 and amides 17, via electrophilic fluorination with one equivalent of F-Teda BF4 (6) of alkenyl boronic acids and trifluoroborates, has been reported.87 The alkenyl fluorides 15 are obtained as Z/E mixtures when the reaction is carried out with one equivalent of F-Teda BF4 in acetonitrile at room temperature. When the reaction is performed with two equivalents of F-Teda BF4 in water or a nitrile solvent the difluoromethyl-substituted alcohols 16 or amides 17, respectively, are obtained. 

Alkyl nitrites can also be used in anhydrous media and, for example, 4-hydroxyben-zenediazonium tetrafluoroborate is isolated in 89% yield after diazotization with isopcntyl nitrite, hydrogen fluoride and boron trifluoride in ethanol/diethyl ether.96 Diazotization can also be performed in dichloromethane or ethers (diethyl ether, tetrahydrofuran, 1,2-dimethoxyethane) with terl-butyl nitrite and boron trifluoride-diethyl ether complex which generates nitrosyl fluoride in situ.229 Excess boron trifluoride is used to trap water and tert-butyl alcohol, so that the reaction can be considered as being performed under complete anhydrous conditions. Yields are higher in dichloromethane, but 1,2-dimethoxyethane is preferred for less soluble amines. This procedure has been successfully applied to the synthesis of mono-and difluorobenzo[c]phcnanthrenes.230... 

Covalent fluorides of group 3 and group 5 elements (boron, tin, phosphorus, antimony, etc) are widely used in 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 fluormated Lewis acids are effective activators of the... 

Thus, for our present purposes a similar approach was followed using Suzuki cross-coupling reactions as the key steps in the synthesis of our target compounds. Symmetrically substituted compounds were synthesized in a twofold Suzuki crosscoupling reaction from commercially available p-substituted phenylboronic acids or esters and 4,4 -dibromobiphenyl or 4,4 -biphenyl-bis-boronic acid ester and a p-substituted arylhalide, respectively, using tetrakis (triphenylphosphino) palladium as catalyst together with cesium fluoride as base in dry tetrahydrofurane as shown in Scheme 8.1. The desired products were obtained in respectable yields after heating at reflux for 50 h. 

In the actual synthesis, aldol reaction 1 involved a lithium enolate whilst aldol reactions 2-4 used boron enolates based on the mandelic acid derivatives described above to incorporate fragments A, B, and C. The aldol products of reactions 2 1 were treated with fluoride and then NaIC>4 to release carboxylic acids which were derivatized or reduced as appropriate. 

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