Lithium fluoroborate

Ammonium and Lithium Fluoroborates. Ammonia reacts with fluoroboric acid to produce ammonium fluoroborate (53). An alternative method is the fusion of ammonium bifluoride and boric acid (54) ... 

Lithium Fluorobora.te, Lithium fluoroborate is used in a number of batteries (qv) as an electrolyte, for example in the hthium—sulfur battery... 

Lithium electrodes, 3 408 standard potential, 3 413t Lithium fluoride, 15 138-139 Lithium fluoroborate, 4 153 manufacture, 4 155 physical properties of, 4 152t thermodynamic properties of, 4 154t uses of, 4 157... 

Bromocatechol borane or LiBp4 (lithium fluoroborate) in acetonitrile (CH3CN) and water has also been used for the deprotection of the MOM group. 

Dworkin AS (1972) Enthalpy of lithium fluoroborate from 298-700 deg.K. Enthalpy and entropy of fusion. J Chem Eng Data 17 284-285... 

Chemicals, Atotech USA, Inc., and General Chemical. The lithium compound is available from Advance Research Chemicals, Cypms Foote Mineral, and FMC Lithium Corp. of America. Small amounts of other fluoroborates are sold by Alfa Inorganics, Inc. and O ark-Mahoning Co. Prices in 1993 for tmddoad quantities were NaBF, 4.95—6.25/kg KBF, 3.55/kg andNH BF 5.03—6.35/kg. 

N-Alkylations, especially of oxo-di- and tetra-hydro derivatives, e.g. (28)->(29), have been carried out readily using a variety of reagents such as (usual) alkyl halide/alkali, alkyl sulfate/alkali, alkyl halide, tosylate or sulfate/NaH, trialkyloxonium fluoroborate and other Meerwein-type reagents, alcohols/DCCI, diazoalkanes, alkyl carbonates, oxalates or malon-ates, oxosulfonium ylides, DMF dimethyl acetal, and triethyl orthoformate/AcjO. Also used have been alkyl halide/lithium diisopropylamide and in one case benzyl chloride on the thallium derivative. In neutral conditions 8-alkylation is observed and preparation of some 8-nucleosides has also been reported (78JOC828, 77JOC997, 72JOC3975, 72JOC3980). 

The double bond in indole and its homologs and derivatives is reduced easily and selectively by catalytic hydrogenation over platinum oxide in ethanol and fluoroboric acid [456], by sodium borohydride [457], by sodium cyanoborohydride [457], by borane [458,459], by sodium in ammonia [460], by lithium [461] and by zinc [462]. Reduction with sodium borohydride in acetic acid can result in alkylation on nitrogen giving JV-ethylindoline [457]. 

High yields of amines have also been obtained by reduction of amides with an excess of magnesium aluminum hydride (yield 100%) [577], with lithium trimethoxyaluminohydride at 25° (yield 83%) [94] with sodium bis(2-methoxy-ethoxy)aluminum hydride at 80° (yield 84.5%) [544], with alane in tetra-hydrofuran at 0-25° (isolated yields 46-93%) [994, 1117], with sodium boro-hydride and triethoxyoxonium fluoroborates at room temperature (yields 81-94%) [1121], with sodium borohydride in the presence of acetic or trifluoroacetic acid on refluxing (yields 20-92.5%) [1118], with borane in tetrahydrofuran on refluxing (isolated yields 79-84%) [1119], with borane-dimethyl sulflde complex (5 mol) in tetrahydrofuran on refluxing (isolated yields 37-89%) [1064], and by electrolysis in dilute sulfuric acid at 5° using a lead cathode (yields 63-76%) [1120]. 

Cross-coupling of alkyl + alkynyl groups Potassium hydroxide-18-Crown-6, 258 Cross-coupling of alkyl + allyl groups Crotyltrimethylsilane, 86 Dimethyl(methylthiosulfonium) tetra-fluoroborate, 121 Lithium, 157... 

Easily dissociable, highly polar organic compounds were used occasionally as cationic initiators. Thus, triphenyl methyl chloride (77), triphenyl methyl chloromercurate (72), alkyl, acyl, and nitronium tetra-fluoro borates (13), silver perchlorate (77, 14), lithium perchlorate (75), acetyl, benzoyl, and tert.-butyl perchlorate (16) and acetyl fluoroborate (16) were mentioned at various times as catalysts for cationically initiable monomers. 

ALKYLATION Benzyltiiethylammonium chloride. n-Butyl mercaptan. Dialkylcar-bonium fluoroborates. Diethoxycarboni-um fluoroborate. Dimethylcopperlithium. Ethyl vinyl ether. Dimethylformamidc dimethyl acetal. Dimethyl sulflde. Dimeth-ylsulfonium methylide. Ethyl chlorofor-mate. Hexamethylphosphoric tiiamide. Lithium diisopropylamide. Lithium N-iso-propylcyclohexylamide. O-Methyldiben-zofuranium fluoroborate. Methyl fluoro-sulfonatc. Naththalene-Sodium. Palladi-um(II) chloride. 1,2,2,6,6-PentamelhyI-pipetidine. Potassium hydroxide. Silver oxide. Sodium bis-2-mcthoxyethoxyaIu-minum hydride. Sodium hydride. Thai-lous ethoxide. 

The ylid 371 prepared by treating cyclopropyltriphenylphosphonium bromide (with lithium diisopropylamide (LDA) produces a useful synthon on reaction with ethyl chloroformate . The fluoroborate salt (372) was shown to be an excellent reagent for cycloalkenylation of carbonyl compounds. The ylid was used successfully in the total synthesis of Spirovetivanes. ... 

Preparation.1 The reaction of lithium N-methylbcnzenesulfonimidoylmethide with benzaldehyde gives (2).2 This is converted by dehydration (TsOH) and methylation with trimethyloxonium fluoroborate into the reagent (1). 

Treatment of ketone 6 with lithium diisopropylamide (LDA) followed by the addition of the racemic aldehyde T yielded the aldol , purified by chromatography, to give an unseparable mixture of epimers. Treatment of 8 with fluoroboric acid in ether led to a precipitate within minutes, and by simple filtration the desired spiroketal 9A was obtained in a 40-50 yield, with correct relative stereochemistry at all three optical centers. The mothers liquors provided additional 9A, a second di astereoi somer 9B and an inseparable mixture CTO of the total) of 10A andTOB. The... 

Generation in situ. Corey1 has generated this highly reactive sulfonium ylide by two methods the preferred method is from diphenylethylsulfonium fluoroborate (2), prepared from diphenyl sulfide (1) and triethyloxonium fluoroborate. This is then heated with 1.1 equiv. of lithium diisopropylamide and 1 equiv. of methylene... 

Rearrangements Aluminum bromide. Calcium carbonate. Dimethylthiocarbamyl chloride Dimsylsodium. 1,3-Dithiane. Lithium diethylamide. Manganese dioxide. Methyl vinyl ketone, 4a —> 5a. Michler s ketone. Norbornene. Perchloric acid. Pinacol-type see Potassium /-butoxide. Potassium /-butoxide. Silver perchlorate. Thallium triacetate. Triethyloxonium-fluoroborate. 

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