Tetra ammonium fluoride

Chloromethoxy-1,2,2 2-tetrafluoroethane is converted by triethylammonium fluoride or piperidine hydrogen fluoride to fluoromethoxy 1 2,2,2-tetra-fluoroethane in greater than 60% yield Piperidine hydrogen fluoride or butyl-ammonium fluoride can convert methoxy-l-chloro-2,2,2-trifluoroethane to methoxy-1,2,2,2-tetrafluoroethane in 80% yield [79]... 

Trimethylsiloxyphenyl isocyanide enters the cyclization reaction with [MCl2(NCPh)2] (M = Pt, Pd) to yield the homoleptic tetracarbenes 77 (M=Pt, Pd) (97JOM(541)51). Complex 77 (M = Pd) enters an interesting reaction with ammonia to yield the species 78 where two of this benzoxazol-2-ylidene ligands are deprotonated and become C-coordinated benzoxazole moieties, while the other two remain intact. Palladium(II) iodide in these conditions behaves differently yielding the di-Mo-cyanide complex, which in the presence of tetra- -butyl ammonium fluoride gives the dicarbene 79. 

TBAF tetra-M-butyl ammonium fluoride-3H20 TFA trifluoroacetic acid... 

The first promising asymmetric aldol reactions through phase transfer mode will be the coupling of silyl enol ethers with aldehydes utilizing chiral non-racemic quaternary ammonium fluorides,1371 a chiral version of tetra-n-butylammonium fluoride (TBAF). Various ammonium and phosphonium catalysts were tried138391 in the reaction of the silyl enol ether 41 of 2-methyl-l-tetralone with benzaldehyde, and the best result was obtained by use of the ammonium fluoride 7 (R=H, X=F) derived from cinchonine,1371 as shown in Scheme 14. 

Another method using starting materials of type 20 includes ring closure via nucleophilic attack at cyclic ketones [60]. Thus, on treatment of compounds 36 with tetra-w-butyl ammonium fluoride (TBAF), the products 37 were isolated. If cyclohex-... 

E-(P-Alkylvinyl)phenyliodonium salts react with tetra-n-butylammonium halides to yield the correspondingly substituted Z-haloethenes (80-100% for chloro-, bromo- and iodo-derivatives) [41], In contrast, in the corresponding reaction with Z-(2-benzenesulphonyl-ethenyl)phenyliodonium salts, nucleophilic substitution occurs with retention of configuration to yield the Z-2-benzenesulphonyl-l-haloethenes [42], The ammonium fluorides fail to yield the fluoroethenes, but produce the ethynes by simple elimination [41]. Where carboxylic acids have low solubility in organic solvents, their conversion into the acid chlorides is frequently difficult. Phase-transfer catalysis not only allows the conversion to be effected rapidly, it also results in high yields of a wide range of acid chlorides [43]. 

Phase-transfer catalysis can be used to mimic high dilution reaction conditions and has been utilized to good effect in the synthesis of large ring lactones [67J. Macrocyclic nitrolactones have also been obtained by rearrangement of 2-(3-hydroxy-propyI)-2-nitrocycloalkanones using a stoichiometric amount of tetra-n-butyl-ammonium fluoride [68]. 

V-(Ethoxycarbonylmethyl)carbodiimides, obtained from the reaction of iminophos-phoranes with aryl isocyanates, undergo cyclization when treated with an excess of tetra-n-butylammonium fluoride at room temperature to yield l,3-oxazlin-5-ones [75] (Scheme 3.9). The ammonium fluoride probably enhances the electrophilic character... 

Carbanions, generated by the reaction of benzylsilanes with tetra-n-butylammo-nium fluoride react with non-enolizable aldehydes to produce the alcohol [67], When a stoichiometric amount of the ammonium fluoride is used, the methylarene corresponding to the benzylsilane is frequently a by-product and arises from formation of the hydrogen difluoride salt during the reaction. When only catalytic amounts of the ammonium fluoride initiate the reaction, the formation of the methylarene is suppressed. In a similar type of reaction (although the mechanism is not known) between aldehydes and ketones, allyl bromide, and tin in the presence of trimethylsilyl chloride the yield of the but-l-en-4-ol is raised significantly by the addition of tetra-n-butylammonium bromide, particularly in the reactions with... 

Optimum yields of (3-vinyl-y-butyrolactols from the Pd(II) promoted reaction of vinyl triflates with Z-but-2-en-l,4-diol (Scheme 6.33) are attained when tetra-n-butylammonium chloride is added (47]. The lactol is conveniently oxidized to the lactone with celite-supported silver carbonate. The corresponding arylbutyrolactols are obtained in high yield (70-80%) from an analogous reaction of iodoarenes with the enediol. The yields of 2-alkenyl-2,5-dihydrofurans, resulting from the Pd(0) catalysed reaction of cyclic alkynylcarbonates with acrylic esters via tandem C-C and C-0 bond forming reactions, are enhanced by the presence of tetra-n-butyl-ammonium fluoride (e.g. Scheme 6.33) (48]. 

E-2-bromomethyleneglutaric esters (>70%) have been obtained from the corresponding 2-bromo-2-bromomethylglutarates using a 25% excess tetra-n-butyl-ammonium fluoride in HMPA [24], A similar procedure converts dimethyl 2-bromo-2-bromomethylsuccinate into dimethyl Z-2-bromomethylenefumarate [25], whereas methyl 2,2-bis(bromomethyl)ethanoate yields the 2-bromomethyl-propenoate when reacted with aqueous sodium hydroxide in the presence of benzyl-triethylammonium chloride [26]. No hydrolysis of the ester is evident at 0°C, but becomes apparent at 25 °C. 

N-Sulphonyl azoles are deprotected by a stoichiometric amount of tetra-n-butyl-ammonium fluoride in THF in good yields (>70%) [19]. 

They chose the TBDMS derivatives for reducing the polarity of hydroxyl groups of hydroxy fatty acid PNB esters because the TBDMS derivatives were resistant to hydrolysis, stable in common organic solvents, and changed the adsorption TLC and RP-HPLC retention of PNB hydroxy fatty acids more than smaller siloxy groups and because the TBDMS groups could easily be removed by fluoride ions (sodium fluoride or tetra-n-butyl ammonium fluoride) to free... 

The complex hydrate structure, 1.67 choline hydroxide-tetra-n-propyl-ammonium fluoride 30-33H2O (space group = R-3, a = 12.533, c = 90.525 A) was discovered by Udachin and Ripmeester (1999b). It should be noted that the tetra-n-propylammonium salt will not form a hydrate on its own (Dyadin et al., 1988), even though other tetra-alkylammonium salts will form a variety of hydrate structures. Similar to structures II, H, and IV, this complex structure consists of stacked sequences of layers, CABBCAABCCABBCAAB. That is,... 

Perfluoroalkyl-chroman-4-ones react with (perfluoroalkyl)trimethylsilane in the presence of a catalytic amount of tetra- -butyl ammonium fluoride (TBAF) to give 2-bis(perfluoroalkyl)-277-chromenes 75 as the major products along with trace amounts of the corresponding 477-chromenes 76 (Equation 41) <2003TL2097>. 

Fig. 11.4 Cavity in the tetra (iso-amyl)ammonium fluoride hydrate. Host water molecules are represented as black dots linked by hydrogen bonds. Fluoride anion is incorporated into this framework (exact position remains unknown). Tetra(iso-amyl)ammonium cation is included in the cavity, its atoms are given by thermal ellipsoids (ORTEP plot)...

J. Lipkowski et al., A novel clathrate hydrate structure of tetra-iso-amyl ammonium fluoride. J. Incl. Phenom. Mol. Recogn. Chem. 9, 275-276 (1990)... 

However, an efficient synthesis of the spirovetivane-sesquiterpene a-Vetispirene 392 was achieved initiating the cleavage of the silicon-cyclopropane carbon bond of 160 by fluoride ion. This was effected with anhydrous tetra-n-butyl ammonium fluoride in THF solution containing acetone at reflux temperature for 10 hr. The pentadienyl anion 387 thus generated experienced highly regioselective addition of acetone at the... 

The most active catalysts for halogenation with perhalomethane are, evidently, quaternary ammonium fluoride salts. One mol% of tetra- -butylammonium fluoride trihydrate (TBAF) can quantitatively transform a malonate ester to an a-chloro derivative at 25 °C with a half-lifetime of 10 minutes (equation 77)628,629 ... 

Feil D, Jeffrey GA (1961) The polyhedral clathrate hydrates, II. Structure of the hydrate of tetra-iso-amyl ammonium fluoride. J Chem Phys 35 1863-1873... 

MACROLiDEs Chloiomethyl methyl sulfide. Dialkylhoryl trifluori imethanesulfonate. Di-n-hutyltin oxide. Dichloroketene. 4-Di-methylamino-3-butyi e-2-one. Keteny 1 i-dene triphenylphospl orane. Tetra-n-butyl-ammonium fluoride. 1,1,6,6-Tetra-n-butyI-1,6-distanna-2,5,7, lO-tetraoxycyclodecane. Tetrakisftriphenylphdsphine)-palladium. N,N,N,Nl-Tetramethylchloro-formamidinium chloride. 

Ammonium uranyl carbonate (AUC) process This process was developed in the 1960 s in the Federal Republic of Germany. It comprises the simultaneous feeding of uranium(Vl) fluoride, carbon dioxide and ammonia into an aqueous ammonium carbonate solution at 70°C, whereupon tetra-ammonium tricarbonato-dioxo-uranate (ammonium uranyl carbonate) precipitates out ... 

Lithium enolates 85 and silyl enol ethers 86 are probably widest in application in modern organic synthesis. The basic rules of selectivity were laid down in chapters 2-4 where many examples were given. We shall simply summarise the position and add some extra versatility from chapters 5-9. These two methods must be taken together because easy interconversion means that a way of making one is a way of making another. In addition, the silyl enol ethers 86 are a source of naked enolates 87 when fluoride is used to remove silicon in the absence of a metal cation. Tetra-alkyl ammonium fluorides such as TBAF (Bu4N+ I ) are usually used. 

TBAI = tetra(n-butyl)ammonium iodide TBAF = tetra(n-butyl)ammonium fluoride... 

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