Tetrabutylammonium triflate

This model was used to explain the kinetics of charge recombination in dye-sensitized Ti02 nanoparticles from measurements of the decay of the cation state of Ru(dcbpy)2(NCS)2 adsorbed on a nanocrystalline Ti02 electrode with an ethanol/0.1 M tetrabutylammonium triflate electrolyte [33], as shown in Fig. 7. 

These reactions are convenient methods for putting sulfur-containing groups onto an aromatic ring. With Ar S", diazosulfides Ar—N=N—S—Ar are intermediates, which can in some cases be isolated. Thiophenols can be made as shown above, but more often the diazonium ion is treated with EtO—CSS" or S2", which give the expected products, and these are easily convertible to thiophenols. Aryl triflates have been converted to the aryl thiol using NaST(P5) and a palladium catalyst, followed by treatment with tetrabutylammonium fluoride. See also 14-27. 

To obtain this compound the key step consisted in the epimerization of the C-5 in compound 6. This was acomplished by triflation of the alcohol 6 and nucleophilic substitution of the triflate by a large excess of tetrabutylammonium acetate in dichloromethane. A controlled (4 °C, 3 h) basic methanolysis of the enol benzoate led to the keto-ester 11" whose hydroxyl functions at C-4 and C-6 were simultaneously deprotected under acidic conditions to furnish 12. Finally a Zemplen deprotection of the 5-acetoxy group led to 13 obtained in five steps and 11% overall yield from 6 (figure 4). 

Using the same initial step for the double serial inversion strategy, from methyl glucoside 37, the 2,4-tiiflate intermediates 50 could be produced via a Inflation process (Scheme 15). The 4-triflates of these intermediates were subsequently inversed to the corresponding 4-0-acetyl intermediates 51 by substitution with tetrabutylammonium acetate, followed by inversion of the 2-position by tetrabutylammonium nitrite, to yield a mixture of methyl... 

Telluride 34 was treated with triflic anhydride in the presence of 1 equivalent of DMSO in dichloromethane at room temperature to give Te-(trifluor-omethyl)dibenzotellurophenium triflate (35). Triflate 35 was also synthesized by treating 34 with bromine in l,l,2-trichloroethane at room temperature followed by triflic acid at reflux temperature. Triflate 35 was converted to bromide 36 by treatment with tetrabutylammonium bromide... 

Voelter and co-workers synthesized the nitrate esters of some carbohydrates by treating the corresponding trifluoromethanesulfonate (triflate) esters with tetrabutylammonium nitrate. Yields were generally excellent. The same authors describe a one-pot process for the synthesis... 

Although aryl bromides and iodides reacted well without any additive (Scheme 32), tetrabutylammonium bromide (TBAB) was effective at improving the reactivity of aryl triflates under these conditions (Scheme 33). 

The key compounds in the synthesis of 4,4 -dithiocello- and -xylotrioses are the per-acetylated 1,4-dithiodisaccharides (43 a, 43 b) (Scheme 14) which are obtained from acylated (39 a, 39 b) by hydrogen bromide treatment and displacement of the halide by potassium or tetrabutylammonium thioacetate. Total deacetylation of the donors and reaction with triflated acceptors (34 a) or (34b) afforded the expected trisaccharides which can be converted after conventional treatment, into free trisaccharides (44d,44e,44g and 44 h) [40]. Using the same stepwise procedure, but with activation of the donor by selective in situ S-de-acetylation and activation, the cellotetraoside (44 i) and cellopentaoside (44j) were obtained in good yield [41]. 

Cycloaddition of benzyne intermediates with aminothiazadienes provide access to substituted 2,4-diamino-4//-l,3-benzothiazines 196 in high yields. The benzynes are prepared by the treatment of (phenyl)[o-(trimethylsilyl)aryl]-iodonium triflates with 1.5 equiv of tetrabutylammonium fluoride (Scheme 20). Interestingly, 3-substituted-l,2-benzisothiazoles 197 are obtained when 4 equiv of tetrabutylammonium fluoride is used <2005H(65)1615>. 

Carbonylative cross-coupling of iodoarenes and aryl triflates with g< ///-fluorovinyltributylstannane takes place smoothly in a standard system, with triflate substrates requiring the addition of tetrabutylammonium iodide (Equation (4)). ... 

The triflate 5 (0.593 g, 1.70 mmol) was combined with the appropriate tetrabutylammonium halide (3.34 mmol) in 30 mL of anhydrous benzene and heated at reflux for 2 h. Alter cooling to room temperature, the benzene was removed under reduced pressure. The residue was dissolved in the minimum amount of dichloromethane, chromatographed on a 2.5 x 10 cm column of 230—400 mesh silica gel with a 3 2 ratio of ethyl ether/hexane... 

The 8-methoxycarbonyloctyl derivative of lactose has been prepared from lactose octaacetate in the presence of tin(lV) chloride or from acetobromolactose in the presence of silver triflate [123,124] and converted into the derivative (108) with a free 4 -hydroxyl group [125] via the 4, 6 -0-benzylidene derivative. The benzyl lactoside (109) was converted into the benzyl ether (110) by the action of benzyl bromide and tetrabutylammonium bromide on the dibutylstannylene derivative [126] and this was converted into the benzoate (111). Phase transfer benzylation of the benzyl lactoside (112) has given the lactose derivative (113) with a free 3-hydroxyl group in 38% yield [118]. 1,6-Anhydrolactose has also been used for the preparation of the protected lactose derivative (114) [127]. 

The methyl 3 -0-allyl-P-lactoside (97) prepared by Veyrieres by the allylation of the dibutylstannylene derivative in the presence of tetrabutylammonium bromide [102] was converted into the per-p-bromobenzyl ether and deallylated to give (306). This was condensed "[106] with the chloride (282) in the presence of silver triflate to give a tetrasaccharide in 68 % yield. This was far superior to the condensation of the oxazoline (294) with (306) which gave a very low yield (9%) of tetrasaccharide. Depro-... 

Silyl triflates may also be used as the catalyst to the same goal. In both cases, conjugated base induces desilylation to create the ylid (compare with the action of tetrabutylammonium fluoride on the same imine which led to the anion see Section VI.B.6.a).333,391... 

Elimination of iodobenzene alone from 2-phenyliodonio benzoate leads to generation of another transient 1,4-dipole which was trapped by phosphaalkynes [55], A new precursor, 2-trimethylsilyl-diphenyliodonium triflate, obtained from 1,2-bis-trimethylsilylbenzene, (diacetoxyiodo)benzene and triflic acid, permitted the generation of benzyne with tetrabutylammonium fluoride, at room temperature [56] ... 

The presence of 1 equivalent of TPP1 OTf- with the chromium anion TpCr(CO)3- as the tetrabutylammonium salt in dichloromethane results in the loss of the carbonyl bands of the anion at 1890 and 1740 cm-1. Their complete replacement by the sharps, band at 2018 cm-1 and the broad E band (1898 and 1838 cm-1) of the 17-electron radical TpCr(CO)3- indicates that the ion-pair annihilation proceeds to completion. Variation of the pyrylium cation, by the replacement of TPP+ with a weaker acceptor such as tri-p-anisylpyrylium triflate (TAP+ OTf-), consistently results in lower conversions of the carbonylmetal anions. For example, the treatment of TpMo(CO)3 with the TAP+ salt leads to a light red solution of TAP (Am 560 nm) (92) and a greatly diminished concentration of TpMo(CO)3- as judged by the reduced carbonyl absorbances in comparison with that obtained from TPP+ at the same concentration. Even with this weaker acceptor cation, however, the strong chromium anionic donor TpCr(CO)3- is completely oxidized by 1 equivalent of TAP+ to form TpCr(CO)3- in essentially quantitative yields. 

The synthesis and chemistry of an 7] -selenophene osmium complex 50 has been studied <19990M1559>. Protonation and electrophilic substitution with acetaldehyde diethyl acetal occurred at C-2. Methylation of complex 50 with methyl triflate gave 51 which upon treatment with tetrabutylammonium borohydride (TBAB) led to the selenophene ring-opened complex 52 (Scheme 5). 

In some systems it is necessary to add a large amount of salts to obtain polymers with low polydispersities. This happens when salts participate in ligand/anion exchange (special salt effect) and when they enhance ionization of covalent compounds through the increase of ionic strength. The special salt effect may either reduce or enhance ionization. Strong rate increases observed in the polymerization of isobutyl vinyl ether initiated by an alkyl iodide in the presence of tetrabutylammonium perchlorate or triflate can be explained by the special salt effect [109]. The reduction in polymerization rate of cyclohexyl vinyl ether initiated by its HI adduct in the presence of ammonium bromide and chloride can be also ascribed to the special salt effect [33]. The breadth of MWD depends on the relative rate of conversion of ion pairs to covalent species and is affected by the structure of the counterions. 

The bis(triflates) can be employed as crude materials immediately after their preparation from aldehydes. The advantages of this method are the easy handling of the fluorinating agent and the mild reaction conditions. Other fluorinating agents, such as tetrabutylammonium fluoride or cesium fluoride/18-crown-6. cleave the S —O bonds of the bis(triflates) and thus produce the starting aldehyde. A variation of this method allows the synthesis of 1-fluoro-l-haloalkanes (see Section 1.1.5.4.). ... 

To a solution of the geni-bis(triflate) (10 mmol) in CHjCU (100 niL) at O C was slowly added a solution of [Bu4N] [Ph3SnF2] (10 mmol) in CHjClj (50 mL). After 4 h (8 h for a-branched aldehydes) the mixture was filtered and the appropriate tetrabutylammonium halide (20 mmol) added. After stirring for 1 h at rt the solvent was evaporated at reduced pressure and the crude mixture filtered through a short (10 cm) column of silica gel. Pure products were obtained by column chromatography (silica gel. pentane). 

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