Bi trifluoroacetate

Phenotellurazine bis(trifluoroacetates) can be obtained by the oxidation of A-methylphenotellurazines with lead dioxide in trifluoroacetic acid solution. The... 

Arylthallium bis(trifluoroacetate)s (10.70) are versatile synthons for various reactions, e.g., acylations (Larock and Fellows, 1982) and photolytic cyanations (Taylor et al., 1970), as shown in Scheme 10-93. Copper-catalyzed cyanations (Uemura et al., 1972) can be carried out at 115 °C with arylthallium (acetate)(perchlorate) (Scheme 10-94). 

The submitters report that p-xylylthallium bis(trifluoroacetate) precipitates after 5 minutes. The checkers did not obtain this precipitate until the bulk of the solvent had been evaporated. 

The reaction of aqueous potassium iodide and -xylylthallium bis(trifluoroacetate) is exothermic and the ether boils off unless the reaction mixture is cooled. 

Mercuration of aromatic compounds can be accomplished with mercuric salts, most often Hg(OAc)2 ° to give ArHgOAc. This is ordinary electrophilic aromatic substitution and takes place by the arenium ion mechanism (p. 675). ° Aromatic compounds can also be converted to arylthallium bis(trifluoroacetates), ArTl(OOCCF3)2, by treatment with thallium(III) trifluoroacetate in trifluoroace-tic acid. ° These arylthallium compounds can be converted to phenols, aryl iodides or fluorides (12-28), aryl cyanides (12-31), aryl nitro compounds, or aryl esters (12-30). The mechanism of thallation appears to be complex, with electrophilic and electron-transfer mechanisms both taking place. 

The 1,1-dimetallic compounds, R2C(SnMe3)ZnBr, were oxidized by dry air at —10 to 0°C in the presence of Me3SiCl to give aldehydes or ketones, R2C=0. In a related indirect method, arylthallium bis(trifluoroacetates) (prepared by 12-21) can be converted to phenols by treatment with lead tetraacetate followed by triphenylphosphine, and then dilute NaOH. Diarylthallium trifluoroacetates undergo the same reaction. ... 

Aryl iodides and fluorides can be prepared from arylthallium bis(trifluor-oacetates) (see 12-21), indirectly achieving the conversions ArH —> Arl and ArH ArF. The bis(trifluoroacetates) react with KI to give Arl in high yields. Aryllead triacetates, ArPb(OAc)3, can be converted to aryl fluorides by treatment with BFs-etherate. ... 

Arylthallium bis(trifluoroacetates) (see 12-21) can be converted to aryl nitriles by treatment with copper(I) cyanide in acetonitrile. Another procedure uses excess aqueous KCN followed by photolysis of the resulting complex ion ArTl(CN)3 in the presence of excess KCN. Alternatively, arylthallium acetates react with Cu(CN)2 or CuCN to give aryl nitriles. Yields from this procedure are variable, ranging from almost nothing to 90 or 100%. 

Another free-radical arylation method consists of the photolysis of aryl iodides in an aromatic solvent. Yields are generally higher than in 14-17 or 14-21. The aryl iodide may contain OH or COOH groups. The mechanism is similar to that of 14-17. The aryl radicals are generated by the photolytic cleavage ArI AR + T. The reaction has been applied to intramolecular arylation (analogous to the Pschorr reaction). A similar reaction is photolysis of an arylthallium bis(trifluoroacetate) (12-21) in an aromatic solvent. Here too, an unsymmetrical biaryl is produced in good yields. ... 

RNH2 (R=alkyl, but not aryl) are phenyliodosyl bis(trifluoroacetate), Phl(0-C0CF3)2 and hydroxy(tosyloxy)iodobenzene, PhI(OH)OTs. A mixture of NBS, Hg(OAc)2, and R OH is one of several reagent mixtures that convert an amide (RCONH2) to the carbamate (RNHCOOR ) (R=primary, secondary, or tertiary... 

A series of benzisothiazolone derivatives 238 has been prepared from methylthiosalicylate 235 O60L4811>. The key cyclization step features the formation of a TV-acylnitrenium ion 237, generated by the hypervalent iodine reagent, phenyliodine(III)bis(trifluoroacetate) (PIFA). This ion cyclizes to benzisothiazol-3-one 238 upon intramolecular trapping of the thiol moiety. 

Somei and co-workers made extensive use of the Heck reaction with haloindoles in their synthetic approaches to ergot and other alkaloids [26, 40, 41, 240-249]. Thus, 4-bromo-l-carbomethoxyindole (69%) [26], 7-iodoindole (91%) (but not 7-iodoindoline or l-acetyl-7-iodoindoline) [40, 41], and l-acetyl-5-iodoindoline (96%) [41] underwent coupling with methyl acrylate under standard conditions (PdlOAc /PhsP/EtjN/DMF/100 °C) to give the corresponding (E)-indolylacrylates in the yields indicated. The Heck coupling of methyl acrylate with thallated indoles and indolines is productive in some cases [41, 241, 246]. For example, reaction of (3-formylindol-4-yl)thallium bis-trifluoroacetate (186) affords acrylate 219 in excellent yield [241], Similarly, this one-pot thallation-palladation operation from 3-formylindole and methyl vinyl ketone was used to synthesize 4-(3-formylindol-4-yl)-3-buten-2-one (86% yield). 

As for chemical paths to cation-radical generation, the following oxidants deserve to be mentioned concentrated (98%) sulfuric acid (Carrington et al. 1959, Hyde and Brown 1962, Carter 1971), persufate (Minisci et al. 1983), iodosobenzene bis(trifluoroacetate) (Alberti et al. 1999), and chlorine dioxide (Handoo et al. 1985, Sokolov et al. 1999). The following metal ions were used in many applications Tl(III) (Elson and Kochi 1973, McKillop and Taylor 1973), Mn(III) (Andrulis... 

Sonochemically induced cation-radical intramolecular cyclization on action of an iodo-nium salt was also demonstrated (Arizawa et al. 2001). Being oxidized with phenyliodonium bis(trifluoroacetate), l-(3-anisyl)-2-(l,3-cyclohexadien-2-yl) ethane formed the cation-radical and then 5 -methoxyspiro[cycloxehane-l,T-indan]-2,6-dione. The yield of this final product was high enough. 

Thieno benzazepine 109 was synthesized in moderate yield by oxidative biaryl-coupling using the hypervalent iodine reagent phenyliodine(lll)bis (trifluoroacetate) (FIFA) and BF3 OEt2 as the activating agent in methylene chloride (Equation (16) (2002X8581)). 

While the silver and zinc salts were effective Lewis acids for these cyclizations, Kikugawa and coworkers reported that the alkoxynitrenium ions could be generated directly from hydroxamic esters (4) using hypervalent iodine oxidants such as hydroxy(tosyloxy) iodobenzene (HUB) and phenyliodine(lll)bis(trifluoroacetate) (PIFA) . Presumably, with such reagents the reactions proceed through A-(oxoiodobenzene) intermediates (54), which can themselves be regarded as anomeric hydroxamic esters and sources of alkoxynitrenium ions (55) (Scheme 11). 

Cycloheptanes.— The C-1—C-2 bond in -y-thujaplicin is essentially single, Co"-/3-thujaplicin-amine complexes have been described, and thermodynamic data on the U -/3-thujaplicin complex have been calculated. The biomimetic cyclization of the silyl enol ether (191) to karahanaenone (192), using methyl-aluminium bis(trifluoroacetate) is almost quantitative (192) is also synthesized by thermolysis followed by desilylation of the silyl enol ether (193) which is readily available from l-bromo-2-methyl-2-vinylcyclopropane and isobutyraldehyde. Dehalogenation of 3-bromo-l-iodo-3-methylbutan-2-one with Zn-Cu couple on alumina in the presence of isoprene yields (192) and minor amounts of the isomers (194) and (195) however, dehalogenation with Fc2(CO)9 favours (195). Acetolysis of karahanaenol tosylate yields anticipated p-menthane derivatives and no filifolene. ... 

Kita has introduced a novel one-pot preparation of 5-methoxylated indoline 55 and indole 56 derivatives by intermolecular addition followed by cyclization between A-tosylaniline derivatives 53 and activated olefins 54 using phenyliodine(III) bis(trifluoroacetate) (FIFA) <99H511785>. In the reaction of 53 with phenyl vinyl sulfides, indoles were produced directly by the spontaneous elimination of thiophenol. 

An interesting new method to cyclize phenylalkylazides to the quinone imine 29 by oxidative cyclization with phenyliodine (III) bis(trifluoroacetate) (PIFA) was reported <99CPB241>. 

Isoxazolo[5,4- ]pyridines have been synthesized via cyclization under oxidative conditions using phenyliodine(iii) bis(trifluoroacetate) (PIFA) (Equation 10 Table 17) <1997SC2217>. 

Arylthallium bis(trifluoroacetates) (see 2-22) can be carbonylated with CO, an alcohol, and a PdCl2 catalyst to give esters 387... 

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