Water sodium triflate

Y(03SCF3)3 to afford a monoaminoalkylation product in good yield in aqueous media.40 Zinc tetrafluoroborate is also highly effective for such couplings in aqueous THF.41 Kobayashi also reported a Mannich-type reaction of imines with silyl enolates catalyzed by neutral salts such as sodium triflate in water as a suspension medium. Unusual kinetic behavior indicates that the presence of the Mannich adduct facilitates the rate of its formation.42... 

Similar aza-Diels-Alder reactions of Danishefsky s diene with imines or aldehydes and amines in water took place smoothly under neutral conditions in the presence of a catalytic amount of an alkaline salt such as sodium triflate or sodium tetraphenylborate to afford dihydro-4-pyridones in high yields (Eq. 12.49).117 Antibodies have also been found to catalyze hetero-Diels-Alder reactions.118... 

Sodium trifluoromethanesulfonate (triflate) was prepared from trifluoromethanesulfonic acid (Aldrich Chemical Company, Inc.) as follows A solution of 26.5 g (0.66 mol) of sodium hydroxide in 50 mL of water was added dropwise to 100 g (0.67 mol) of triflic acid chilled in an ice bath. The solution was concentrated to dryness with a rotary evaporator, and the residual solid was recrystallized from 65 mL of acetonitrile. The collected solid was dried at 80°C under vacuum for 24 hr to give 90 g of pure sodium triflate. 

Hendrickson synthesized allyl triflones using tetrabutylam-monium triflinate. The quaternary ammonium system is more soluble and 20-40 times more reactive than the conventional potassium triflinate. Tetra-n-butylammonlum azide (6) prepared from tetra-/3-butylammonium hydroxide and sodium azide reacts with triflic anhydride in chloroform at —78°C to give a 1 1 mixture of tetrabutylammonium triflinate (7) and tetrabutyl-ammonium triflate (8). Treatment of this mixture with allyl bromide gives the corresponding allyl triflone (5) in almost quantitative yield. The water-soluble triflate coproduct (8) in the reaction mixture does not interfere with the formation of (5), which is readily Isolated (eq 4). 

The aza-Diels-Alder reaction of imines with diene of Danishefsky is an important route to 2,3-dihydro-4-pyridones. A number of Lewis acids have been used to catalyze the reaction in organic solvents. In water the reaction was realized by acid catalysis via iminium salts or by Bronsted acids. The montmorillonite K-10 catalyzed this cycloaddition in water or in aqueous acetonitrile in excellent yield. Recently Kobayashi has performed the reaction in water at room temperature under neutral conditions in two (imine - - diene) or three (aldehyde -b amine -b diene) component versions by using sodium triflate as catalyst. Imine intermediates from the indium-mediated reaction, in aqueous medium at 50° C, between aromatic nitro compounds and 2,3-dihydrofuran undergo aza-Diels-Alder cycloadditions to give tetrahydroquinoline derivatives in good overall yields. ... 

Kobayashi and coworkers showed that Lewis add surfactant-combined catalysts such as scandium tris(dodecyl sulfate), Sc(03SCi2H25)3, or copper bis(dodecyl sulfate), Cu(03SCi2H25)2, were efficient catalysts for the three-component Mannich-type reaction, with 73-95% yield being obtained in neat water.Neutral salts such as sodium triflate and sodium iodide catalyzed the condensation reaction in water between preformed imines and silicon enolates, or the three-component Mannich-type reaction using aromatic amines, with 49-93% yields and 0-80% diastereoselectivities. Mechanistic studies indicated that both sodium triflate and the Mannich adduct itself cooperatively promote the reaction. 

Data reported for the protolysis constant of water in sodium triflate media are listed in Table 5.29. The data have been acquired across a temperature range of 25-250 °C, with the data reported by Palmer and Drummond (1988). 

Few data have been reported for the osmotic coefficient data of sodium triflate solutions. Rard, Palmer and Albright (2003) gave data for only two temperatures, 25 and 50 °C. Equation (5.18) was used to determine water activity data from these osmotic coefficient data. At these two temperatures, the dependence of the water activity data on ionic strength in sodium triflate solutions can be described by Eq. (5.19), and the values derived for and 2 are listed in Table 5.30. 

The ionic strength dependence of the protolysis constant of water in sodium triflate media and at 25 C is illustrated in Figure 5.29. The solid line on the figure is derived from the use of Eq. (5.17) with logliC, ° = -13.994 0.014. From use of the equation, the following ion interaction parameters are derived ... 

The metallic salts of trifluoromethanesulfonic acid can be prepared by reaction of the acid with the corresponding hydroxide or carbonate or by reaction of sulfonyl fluoride with the corresponding hydroxide. The salts are hydroscopic but can be dehydrated at 100°C under vacuum. The sodium salt has a melting point of 248°C and decomposes at 425°C. The lithium salt of trifluoromethanesulfonic acid [33454-82-9] CF SO Li, commonly called lithium triflate, is used as a battery electrolyte in primary lithium batteries because solutions of it exhibit high electrical conductivity, and because of the compound s low toxicity and excellent chemical stabiUty. It melts at 423°C and decomposes at 430°C. It is quite soluble in polar organic solvents and water. Table 2 shows the electrical conductivities of lithium triflate in comparison with other lithium electrolytes which are much more toxic (24). 

A solution of 1 equivalent of the oxazolidinone in diethyl ether is cooled to —78 C. To the resultant suspension are added 1.4 equivalents of triethylamine. followed by 1.1 equivalents of dibutylboryl triflate. The cooling bath is removed and the reaction mixture is stirred at 25 °C for 1.5 h. The resultant two-phase mixture is cooled to — 78 "C with vigorous stirring. After 1 equivalent of aldehyde is added, the reaction is stirred at —78 °C Tor 0.5 h, and 0 "C for 1 to 2 h. The solution is diluted with diethyl ether, washed with 1 N aq sodium bisulfate, and concentrated. Following oxidation with 30% aq hydrogen peroxide (10 equivalents, 1 1 methanol/water, 0 C. 1 h), extractive workup and chromatographic purification, the aldol adduct is obtained with >99% diastcrcomeric purity. 

While the Lewis acid-catalyzed aldol reactions in aqueous solvents described above are catalyzed smoothly by several metal salts, a certain amount of an organic solvent such as THF had still to be combined with water to promote the reactions efficiently. This requirement is probably because most substrates are not soluble in water. To avoid the use of the organic solvents, we have developed a new reaction system in which metal triflates catalyze aldol reactions in water with the aid of a small amount of a surfactant, such as sodium dodecyl sulfate (SDS). 

The iodonium triflate (460 mg, 1 mmol) was added to a stirred slurry of anhydrous sodium p-toluene sulphinate (180 mg, 1.01 mmol) in dichloromethane (15 ml) at 20°C under nitrogen. After 15 min water (10 ml) was added and the phases were separated the aqueous layer was extracted with additional dichloromethane (2 x 5 ml), and the combined organic extracts were dried. The filtered solution was treated with hexanes (30 ml) and concentrated. The solid residue was purified by radial chromatography (silica gel, 200-400 mesh, dichloromethane-hexanes) to afford 3-tosyl-bicyclo[3.2.0]-3-heptene-2-one (197 mg, 75%), m.p. 164-165°C. The method is general for the preparation of sulphones with a cyclopentenone moiety other alkenyl iodonium salts gave alkynyl sulphones with sulphinates (Section 9.4.4). 

The lanthanide triflate remains in the aqueous phase and can be re-used after concentration. From a green chemistry viewpoint it would be more attractive to perform the reactions in water as the only solvent. This was achieved by adding the surfactant sodium dodecyl sulfate (SDS 20 mol%) to the aqueous solution of e.g. Sc(OTf)3 (10 mol%) [145]. A further extension of this concept resulted in the development of lanthanide salts of dodecyl sulfate, so-called Lewis acid-surfactant combined catalysts (LASC) which combine the Lewis acidity of the cation with the surfactant properties of the anion [148]. These LASCs, e.g. Sc(DS)3, exhibited much higher activities in water than in organic solvents. They were shown to catalyze a variety of reactions, such as Michael additions and a three component a-aminophosphonate synthesis (see Fig. 2.44) in water [145]. 

Liquid extraction was used to make diastereomers, exploiting the high solubility of potassium triflate in water compared with the binaphthylphosphate salts. The two diastereomers have different solubilities and the (+) isomers of knot and anion crystallise together [49, 50], while the laevorotatory knot remains soluble. Counterion exchange with hexafluorophosphate gave the pure topological enantiomers. The optical rotatory power of the copper knots is very high At the sodium D-line (589 nm), the optical rotatory power was 7.000 mol 1 L dm They are beautiful molecules with a remarkable property ... 

The surfactant-aided Lewis acid catalysis was first demonstrated in the model reaction shown in Table 13.1 [22]. While the reaction proceeded sluggishly in the presence of 10 mol% scandimn triflate (ScfOTOs) in water, a remarkable enhancement of the reactivity was observed when the reaction was carried out in the presence of 10 mol% Sc(OTf)3 in an aqueous solution of sodium dodecyl sulfate (SDS, 20 mol%, 35 mM), and the corresponding aldol adduct was obtained in high yield. It was found that the type of surfactant influenced the yield, and that Triton X-100, a non-ionic surfactant, was also effective in the aldol reaction (but required longer reaction time), while only a trace amount of the adduct was detected when using a representative cationic surfactant, cetyltrimethylammonium bromide (CTAB). The effectiveness of the anionic surfactant is attributed to high local concentration of scandium cation on the surfaces of dispersed organic phases, which are surroimded by the surfactant molecules. 

Other Alkylation Experiments. In other experiments lithium and sodium were used in place of potassium. Biphenyl and anthracene were used in place of naphthalene. 1,2-Dimethoxyethane was used in place of tetrahydrofuran. Butyl chloride, butyl bromide, butyl mesylate, butyl triflate, methyl iodide, and octyl iodide were used in place of butyl iodide. The conditions used in these experiments were very similar to the conditions used in the procedures described in the previous paragraphs. The isolation procedure was modified in those cases where the ionic salt, e.g., sodium iodide, was soluble in tetrahydrofuran. In these instances the tetrahydrofuran-soluble product was washed with water to remove the salt prior to further study. 

A mixture of NiCh (11.0 mg, 0.0849 mmol) and CrCh (493 mg, 3.88 mmol) in degassed DMF (3 mL) was stirred at 0 °C for 10 min. A solution of the aldehyde (505 mg, 0.962 mmol) in DMF (3 mL) and a solution of the triflate (653 mg, 1.68 mmol) in DMF (3 mL) was added to the mixture at room temperature, and the resulting mixture was stirred at room temperature for 25 h. The reaction mixture was diluted with water and extracted with ether, washed with saturated sodium chloride, dried, and concentrated. The crude product was purified via chromatography eluting with n-hexane EtOAc (5 1) to give 610.4 mg (83%) of a diastereomeric mixture of allylic alcohols. 

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