Fluoride as base

Phenacyl esters can be prepared from the phenacyl bromide, a carboxylic acid, and potassium fluoride as base. These phenacyl esters can be cleaved by irradiation (313 nm, dioxane or EtOH, 20°, 6 h, 80-95 % yield, R = amino acids > 300 nm, 30°, 8 h, R = a gibberellic acid, 36-62% yield ). Another phenacyl derivative, RC02CH(C0C6H5)C6H3 3,5-(0CH3)2, cleaved by irradiation, has also been reported. ... 

Reinhoudt, de Jong and Tomassen have explored the use of metallic fluorides as bases in the Williamson ether synthesis of crowns. They found that the efficacy order for the metal cations they examined was Cs" > Rb > > Na Li . This order was... 

Use of caesium fluoride as base to effect condensation caused an explosion in absence of solvent. Pyridine or potassium fluoride, and use of dichloromethane gave satisfactory results. 

H-Ala-Cys(Fam)-OMe by Famesylation in Organic Media with Potassium Fluoride as Base Typical Procedure 48 ... 

In tetrafluorobenzene-l,3-dicarbonitrilc the 4-fluorine is highly activated and can be specifically eliminated to give products 5 in good yield under very mild conditions, using acetonitrile as solvent and potassium fluoride as base.50... 

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. 

The application of cesium fluoride as base in the synthesis of crown compounds from phenols and the ditosylates of polyethylene glycols was first described by Reinhoudt [44]. This method uses the high basicity of weakly solvated ( naked ) fluoride anions under aprotic conditions and is based on the formation of very stable H—F bonds (approx. 569 kJ/mol, H—Cl approx. 432 kJ/mol for comparison) [8],... 

The reactivity of l,3,6,8-tetraazatricyclo[4.4.1.1]dodecane 118 (TATD) in basic media to give l,3,6,8-tetraazatricyclol4.3.1.1 lundecane 119 (TATU) has been studied. When ammonium hydroxide or ammonia gas was used only 12% of 119 was obtained. Better results were obtained by using ammonium fluoride as base <04TL7563>. 

A rapid MW-assisted palladium-catalyzed coupling of heteroaryl and aryl boronic acids with iodo and bromo-substituted benzoic acids, anchored on TentaGel has been achieved [222]. An environmentally friendly Suzuki cross-coupling reaction has been developed that uses polyethylene glycol (PEG) as the reaction medium and palladium chloride as a catalyst [223]. A solvent-free Suzuki coupling has also been reported on palladium-doped alumina in the presence of potassium fluoride as base [224]. This approach has been extended to the Sonogashira coupling reaction wherein terminal alkynes couple readily with aryl or alkenyl iodides on palladium-doped alumina in the presence of triphenylphosphine and cuprous iodide (Scheme 8.89) [225]. 

A new phosphorylating reagent, dibenzyl phosphorofluoridate, has been introduced. In the presence of caesium fluoride as base it reacts with primary and anomeric hydroxy groups preferentially. Secondary hydroxy groups, e.q.. those of partially protected myo-inositol, can be phosphorylated after deprotection with butyl lithium. 1,2-Di-phosphates were obtained in good to excellent yields by treatment of vicinal diols with diethyl phosphorochloridate and butyl lithium there was no evidence of formation of cyclic phosphates, the predominant products when other bases are used. Q-Glycosylation of phosphonic and phosphinic acids has been achieved by the trichloroacetimidate method examples are given in Scheme 4. ... 

However, many substances, notably alcohols, have a greater proton affinity than the hydrogen fluoride molecule, and so behave as bases, for example ethanol ... 

Methyl, ethyl, and benzyl ethers have been prepared in the presence of tetraethylammonium fluoride as a Lewis base (alkyl halide, DME, 20°, 3 h, 60-85% yields). ... 

Epoxides are regio- and stereoselectively transformed into fluorohydrins by silicon tetrafluoride m the presence of a Lewis base, such as diisopropyleth-ylamme and, m certain instances, water or tetrabutylammonium fluoride The reactions proceed under very mild conditions (0 to 20 C in 1,2-diohloroethane or diethyl ether) and are highly chemoselective alkenes, ethers, long-chain internal oxiranes, and carbon-silicon bonds remain intact The stereochemical outcome of the epoxide ring opening with silicon tetrafluoride depends on an additive used, without addition of water or a quaternary ammonium fluoride, as fluorohydrins are formed, whereas m the presence of these additives, only anti opening leading to trans isomers is observed [17, 18] (Table 2)... 

Reaction of the secondary silylnitronate 4 with acetaldehyde, catalyzed by anhydrous tetra-butylammonium fluoride, furnished only 20% of the desired product 5 as a 56 44 (R, S )j (R, R ) mixture. With tetrabutylammonium fluoride trihydrate as base the yield increased to 89% while the diastereoselectivity remained low16. 

Palladium-catalyzed hydroarylation of sterically hindered PTAD adduct 157 with aryl halides in the presence of triphenylarsine, sodium acetate, and DMSO provides a 1 1 mixture of 170 and 171. The same reaction done with sodium fluoride and formic acid provides mixtures containing 171 as the major product. Apparently, the use of sodium fluoride as a base allows the selective formation of the opening products 171 in good yields (Equation 19). Similarly, the 2,3-phthalazine-l,4-dione adduct 172 provides the corresponding products 173 and 174 (Equation 20) <2002AGE3375>. 

Scheme 6 Double farnesylation under basic conditions using potassium fluoride as a base.

Gel polymer lithium-ion batteries replace the conventional liquid electrolytes with an advanced polymer electrolyte membrane. These cells can be packed in lightweight plastic packages as they do not have any free electrolytes and they can be fabricated in any desired shape and size. They are now increasingly becoming an alternative to liquid-electrolyte lithium-ion batteries, and several battery manufacturers. such as Sanyo. Sony, and Panasonic have started commercial production.Song et al. have recently reviewed the present state of gel-type polymer electrolyte technology for lithium-ion batteries. They focused on four plasticized systems, which have received particular attention from a practical viewpoint, i.e.. poly(ethylene oxide) (PEO). poly (acrylonitrile) (PAN). ° poly (methyl methacrylate) (PMMA). - and poly(vinylidene fluoride) (PVdF) based electrolytes. ... 

The selective alkylation of a chemically distinct phenohc site on a perfluorinated aromatic has been achieved following a polymer assisted solution phase protection of an alternative o-hydroxybenzoic acid unit as the dioxin-4-one (19) (Scheme 2.45) [66]. A diverse set of 22 different alkyl and benzyl bromides were then attached to the free phenol using cesium fluoride as the base, followed by treatment with Amberlyst 15 and Amberlyst A-21 as the work-up. Subsequent hydrolysis of the dioxin-4-one group with NaOH proceeded smoothly and was quenched... 

Nitric acid is formed during these reactions and in some cases the addition of sodium fluoride as a base can be advantageous. This is the case with higher carbohydrates like cellulose and... 

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