Trifluoroacetate salt

Diels-Alder reactions Neutral ionic liquids have been found to be excellent solvents for the Diels-Alder reaction. The first example of a Diels-Alder reaction in an ionic liquid was the reaction of methyl acrylate with cyclopentadiene in [EtNH3][N03] [40], in which significant rate enhancement was observed. Howarth et al. investigated the role of chiral imidazolium chloride and trifluoroacetate salts (dissolved in dichloromethane) in the Diels-Alder reactions between cyclopentadiene and either crotonaldehyde or methacroline [41]. It should be noted that this paper describes one of the first examples of a chiral cationic ionic liquid being used in synthesis (Scheme 5.1-17). The enantioselectivity was found to be < 5 % in this reaction for both the endo (10 %) and the exo (90 %) isomers. 

Thallium(III), particularly as the trifluoroacetate salt, is also a reactive electrophilic metallating species, and a variety of synthetic schemes based on arylthallium intermediates have been devised.75 Arylthallium compounds are converted to chlorides or bromides by reaction with the appropriate cupric halide.76 Reaction with potassium iodide gives aryl iodides.77 Fluorides are prepared by successive treatment with potassium fluoride and boron trifluoride.78 Procedures for converting arylthallium compounds to nitriles and phenols have also been described.79... 

The key feature of the first total synthesis of (+)-homopumiliotoxin 223G 418 was a Lewis acid-induced, chelation-controlled propargylation of the trifluoroacetate salt of (. )-2-acetyl pi peri dine 415, derived from iV-Cbz-L-pipecolinic acid. Alkyne 416 thus formed was transformed after several steps into 417, which was cyclized by activation of the primary hydroxyl with the carbon tetrabromide-triphenylphosphine system to give the natural product (Scheme 98) <1998TL2149>. 

CAS 4368-28-9 39920-04-2 (Racemic mixture) 629653-73-2 (Acetate salt) 18660-81-6 (Citrate salt) 17522-62-2 (Formate salt) 4664-41-9 (Hydrobromide salt) 4664-40-8 (Picrate salt) 129497-92-3 (Trifluoroacetate salt)... 

The final conditions were scaled up with no problems chalcone 8a and guanidine (liberated from its hydrochloride with sodium ethoxide) were heated in dimethyl acetamide while bubbling air through the mixture to form pyrimidine 9a. After complete conversion (16 h), the product was cleaved from the support (20% trifluoroacetic acid in DCM). Pure 4-(2-amino-6-phenyl-pyrimidin-4-yl)bcnzamidc 1 was obtained as its trifluoroacetate salt upon evaporation of the filtrate and recrystallisation of the residue from ethanol/water in 56% overall yield based on the solid phase attached 4-carboxybenzaldehyde 6a. 

We have subjected the mechanistic proposal of Fig. 1 to a direct test. N,N-Dimethylformaldimmonium ion was independently prepared as its trifluoroacetate salt and was mixed with a slight excess of silver nitrite in acetonitri1e-d3. The only product identified was dimethylnitrosamine, which was produced in greater than 90% yield ( ). No direct evidence for intermediates of structure I could be obtained, as the reaction was complete within the few minutes required to analyze the mixture by running its NMR spectrum. 

The ascidian Lissoclinum japonicum from Palau contained the antimicrobial and antifungal metabolites N,N-dimethyl-5-(methylthio)varacin and 3,4-dimethoxy-6-(2 -iV,./V-dimethylaminoethyl)-5-(methylthio)benzotrithiane, both of which were isolated as the trifluoroacetate salts <1994T12785>. They selectively inhibit protein kinase. Also, varacin and three new antimicrobial marine polysulfides, varacins A-C, were isolated from the Far Eastern ascidian Polycitor sp. <1995JNP254>, extracted from the New Zealand ascidian Lissoclinum notti <2002T9779>. 

Reaction scheme showing the thermodynamically controlled condensation of tetraformylcavitand 1 with ethylenediamine to form an octahedral nanocontainer 2, which undergoes reduction to yield the trifluoroacetate salt 2-24CF3COOH. 

Pramanik s group. He reasoned that the hydrolysis of dihydrohypoxanthine to 5-aminoimidazole-4-carboxamide (AIC) (see Scheme 19 and Figure 14 in Case Study 2) might be conveniently carried out using microwave irradiation. He dissolved dihydrohypoxanthine trifluoroacetate salt (81.1 mg) in 1 1 trifluoroacetic acid water (2 ml) and micronized the solution for 2 min at ambient pressure. After this time the electrospray-MS spectrum of the solution indicated that substantial AIC formation had occurred (Figure 1). 

To a mixture of adamantyl bromide (0.5 mmol) and trifluoroacetate salt of lepidine (2.5 mmol) in benzene (6 ml) were added (trimethylsilyl)silane (1.0 mmol) and AIBN (1.0 mmol). The mixture was heated at 80 °C for 14 h under an argon atmosphere. After the reaction, the reaction mixture was washed with sat. aq. NaHC03. The organic layer was dried over Na2S04. After removal of the solvent, the residue was chromatographed on silica gel to give 2-(l-adamantyl)-4-methylquinoline in 90% (125 mg) yield [33]. 

The purified proteins are dialyzed extensively against two changes of 1% acetic acid and finally against 0.1% trifluoroacetic acid They can be stored as lyophilized powders at -20°C or -80°C and are stable at room temperature for a few days. It is very important to dissolve them in H20 and not buffers or medium, since on lyophilization they form the trifluoroacetate salt, but once in aqueous solution at low pH can be adjusted to the required physiological pH. We routinely dissolve them in H20 at a concentration 10-fold higher than required, and dilute 10-fold into the required buffer or medium. This does not pose a problem even for micromolar concentrations, since all of the chemokines that we have worked with are soluble at 1.25 mM or 10 mg/mL. 

The Step 1 product (0.25 mmol) was added to the well of a reaction block containing 5 ml THF and then A-benzyl-A-ethylamine (0.5 mmol) was added neat. The reaction block was shaken 24 hours then filtered, concentrated, and purified using reverse-phase HPLC with water/acetonitrile (0.1% TFA) and the product isolated as a trifluoroacetate salt. 

Table 1 HPLC retention times of trifluoroacetate salts for selected experimental bradykinin Bj receptor antagonists agents...

Removal of the endo methylene bridge of Troger s bases could be achieved with or without concomitant methylation of the nitrogen(s). Thus, trifluoroacetylation of 215b with trifluoroacetic anhydride did not give the expected bis(tri-fluoroacetamide) 217 (R1 = R2 = CF3CO) but rather the trifluoroacetamide trifluoroacetate salt 216 in 79% yield. 

The carboxylates of indium and thallium are obtained by dissolving the oxides in acid. Acetate and trifluoroacetate salts are used extensively as reagents in organic synthesis. Certain other thallium compounds have been used also. The trifluoroacetate, T1(02CCF3)3, will directly thallate aromatic compounds to give arylthal-lium species, for example, C6H5T1(02CCF3)2 (cf. aromatic mercuration, Section 15-15) and oxidize arenes to biaryls. 

The product from Step 3 was suspended in 2 ml CH2CI2, 4 ml trifluoroacetic acid added, and mixture agitated 3 days. Thereafter, the mixture was filtered, washed with CH2CI2, methyl alcohol, the combined filtrates concentrated, dried under vacuum, and the product isolated as the trifluoroacetic salt in 32% yield, 90% purity. H-NMR, MS, and elemental analysis data supplied. 

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