Trifluoroacetyl reactions with

Carbazole, 2-hydroxy-reactions with citral, 4, 235 Carbazole, 2-hydroxy-9-methyl-synthesis, 4, 294 Carbazole, N-hydroxymethyl-as metabolite of carbazole, 1, 230 Carbazole, N-isopropyl-PE spectroscopy, 4, 190 Carbazole, A7-methyl- N NMR, 4, 175 X-ray spectroscopy, 4, 163 Carbazole, 1-nitro-synthesis, 4, 282 Carbazole, tetrahydro-dehydrogenation, 4, 282, 312 synthesis, 4, 107, 337, 353 Carbazole, 1,2,3,4-tetrahydro-reduction, 4, 255, 256 synthesis, 4, 312, 325, 352 Carbazole, 1,2,3,4-tetrahydro-1 -oxo-synthesis, 4, 337 Carbazole, 9-trifluoroacetyl-synthesis, 4, 218 Carbazole, vinyl-polymers, 1, 275, 301 Carbazole, 9-vinyl-copolymer... 

Hexafluoropropylene oxide (HFPO), which decomposes reversibly to di-fluorocarbene and trifluoroacetyl fluonde with a half-life of about 6 h at 165 °C [30], is a versatile reagent. Its pyrolysis with olefins is normally carried out at 180-2(X) °C, and yields are usually good with either electron-nch or electron-poor olefins [31, 32, 33, 34, 35, 36, 37] (Table 2). The high reaction temperatures allow the eyclopropanation of very electron poor double bonds [58] (equation 10) but can result in rearranged products [39, 40, 41] (equations 11-13)... 

The reaction of Ab-acetyl-1 -hydroxytryptamine (39) with mesyl chloride (MsCl) in THF in the presence of EtsN provides 1-acetyl-1,2,3,8-tetrahydropyrrolo[2,3-(j] indole (49a, 35%) (70JA343), Ab-acetyl-6-mesyloxytryptamine (50a, 4%), Ab-acetyl-2,3-dihydro-2-oxotryptamine (51a, 5%), l-acetyl-3a-(4-chlorobutoxy)-l,2,3,3a,8,8a-hexahydropyrrolo[2,3-(j]indole (52a, 7%), and Ab-acetyltryptamine (53a, 2%) as shown in Scheme 6 (2000H483). In the same reaction with MsCl, l-hydroxy-Ab-methoxycarbonyltryptamine (34) produces 50b (7%), 51b (34%), and 52b (9%), while the formation of 49b is not observed at all. In the case of Ab-trifluoroacetyl-l-hydroxytryptamine (48), 49c (45%), 50c (8%), 51c (4%), and 52c (6%) are produced. These data suggest that the yield of 49 increases, whereas the yield of 51 decreases in the order of electron-withdrawing ability of Ab substituents (COOMe < COMe < COCF3). Stability of 49 seems to govern the quantity of 51, which is probably formed by hydrolysis of 49. 

Trifluoroacetylbenzotriazole,[125a] which is easily prepared from benzotriazole and trifluoroacetic anhydride, is a very expedient trifluoroacetylating agent. Because of its stability the solid product can be stored in the covered bottle for several weeks without decomposition. By reaction with alcohols the trifluoroacetate esters were obtained in high yields ... 

As for the reaction with alcohols N -trifluoroacetylbenzotriazole is conveniently used for trifluoroacetylation of primary or secondary alkyl or aryl amines to give excellent yields of trifluoroacetamides [95al... 

V-Benzoyl-C-phenylglycine with trifluoroacetic anhydride at room temperature yields the bright yellow 4-trifluoroacetyl-l,3-oxazol-5-one (66, R = R = Ph R = COCFj), but the corresponding reaction with... 

Chloro, 3-bromo, 3-iodo, and 3-nitro derivatives of 5,7-dimethyl-pyrazolo[l,5-a]pyrimidine derivatives were prepared by chlorination, bromination, iodination, and nitration of 3-unsubstituted 5,7-dimethyl-pyrazolo[l,5-a]pyrimidines. Reaction with bromine and potassium thiocyanate gave a 3-thiocyanato derivative, which was converted into the mercapto derivative upon saponification. Nitrosation gives the 3-nitroso derivative and acylation with trifluoroacetic anhydride affords the trifluoroacetyl derivative (74JMC645 77JMC386). 

The aerobic pathway of metabolism (pathway 1) (Fig. 7.77) produces trifluoroacetyl chloride, a highly reactive acyl chloride, which can react with nucleophiles such as amino groups similar to those on proteins. Alternatively, reaction with water yields trifluoroacetic acid. Trifluoroacetylchloride is the probable reactive metabolite that trifluoroacylates protein, most probably at lysine residues (Fig. 7.77). Removal of the trifluoroacyl moiety from the... 

Trifluoroacetyl hypofluorite is the main product in the low-temperature fluorination of sodium trifluoroacetate in suspension in an inert solvent, and can be further transformed to pentafluoro-(fluoroxy)ethane.2 In some cases, the reaction mixture of up to four reactive products [fluoroxy, bis(fluoroxy) and acyl hypofluorites], formed in reactions with various acid salts, c.g. 5, has been directly used for the fluorination of organic molecules.1 " 5... 

Acetyl hypofluorite appears to be a milder reagent than trifluoroacetyl hypofluorite in the fluorination of alkenes and acetylenes. Acetyl hypofluorite undergoes addition to the C = C bond in the fluorination of cyclohexene the ij f7-adduct 4 is obtained in 60% yield, while the reaction with dodec-l-ene gives 2-acctoxy-l-fluorododccanc (5) in 30% yield.10... 

Reactions with acetylenes have been much less intensively studied, but important and large differences between trifluoromethyl hypofluorite and trifluoroacetyl hypofluorite have been observed.2 An example of the reactivity of trifluoroacetyl hypofluorite with acetylenes is given by the reaction with 1,2-diphenylacetylene (23) acetyl hypofluorite is unreactive even at room temperature.10... 

The C-acyl heterocycles do not generally form hydrates under acidic or alkaline conditions unless the five-membered ring is also substituted with a second electron-withdrawing group or, as with the trifluoroacetyl and trichloroacetyl derivatives, the carbonyl group is activated to nucleophilic attack. Such activated substituents also undergo the normal reactions with aqueous sodium hydroxide, sodium alkoxide and with amines to give the appropriate... 

A recent procedure which utilizes the pivaloyl derivative of o-bromoaniline as one of the fragments is also a type llac approach. The compound is converted to its dilithio derivative at -78 °C. Reaction with a-halo ketones then affords indole hydrates by N-alkylation and reaction of the o-lithiated position with the carbonyl group dehydration subsequently yields indoles (equation 108) (81TL1475). The (V-trifluoroacetyl and N-t-butoxycarbonyl derivatives of o-bromoaniline exhibit similar reactivity. 

Thiophene is far more reactive than benzene in electrophilic substitution reactions. Reaction with bromine in acetic acid has been calculated to be 1.76 x 109 times faster than with benzene (72IJS(C)(7)6l). This comparison should, of course, be treated with circumspection in view of the fact that the experimental conditions are not really comparable. Benzene in the absence of catalysts is scarcely attacked by bromine in acetic acid. More pertinent is the reactivity sequence for this bromination among five-membered aromatic heterocycles, the relative rates being in the order 1 (thiophene) and 120 (furan) or, for trifluoroacetylation, 1 (thiophene), 140 (furan), 5.3 xlO7 (pyrrole) (B-72MI31300, 72IJS(C)(7)6l). Among the five-membered heteroaromatics, thiophene is definitely the least reactive. 

From the synthetic viewpoint, a particularly interesting trifluoroacetylation reaction of simple vinyl ethers was reported first by Hojo et al in 1976 [73] The scope and limitation of this particular reaction were elaborated intensively, the reaction proved to be of general applicability with practically no restrictions on substituents of the vinyl ether moiety 9] (equation 34) This general validity is particularly beneficial because a trifluoroacetylated vinyl ether is the synthetic equivalent of a specifically protected tnfluoromethyl-substituted 1,3-dicarbonyl compound 19], thus the reaction provides access to a broad spectrum of variously substituted synthetic building blocks with selective reactivities on each carbon acceptor (a) and donor (d) center (equation 35) Obviously, such building blocks can react as heterodiene systems m cycloaddition reactions [< 74] or can be treated with a wide variety ot 1,2 or 1 3-dinucleophihc species to give any desired tnfluoromethyl-substituted carbocychc or heterocyclic system [8 75] Treatment of simple vinyl ethers with an excess of trifluoroacetic anhydride at elevated temperature leads to doubly acylated products [76] Comparable acylation reactions occur with vinyl thioethers [73], and the mesoiomc l,3-oxathiol-4-ones show, at least in a formal sense, similar behavior [77] (equation 36)... 

The involvement of the lysine residues has been explored. Thus, trifluoroacetylation of lysine residues 13, 55 and 99 has been carried out,662 but only modification of residue 13 affects the reaction with cytochrome oxidase. Modification of lysine residues 13, 25, 27, 72 and 79 decreased the reaction rate of cytochrome c with cytochrome bs. It is possible that the lysine groups in unmodified cytochrome c interact with the carboxylate groups in cytochrome b5 (Asp-48, Glu-43, Glu-44 and Asp-60) and one of the heme propionate groups.663 In general, such studies support the proposal that these lysine groups represent binding sites for redox partners of cytochrome c. 

Following their syntheses of ( )-pancracine and related alkaloids (vide supra), Hoshino et al [106] had described a different approach involving radical cyclisation of an isoquinoline derivative which permitted a rapid assembly of keto-5,11-methanomorphanthridine skeleton. The syntheses of 413, 414 and 415 commenced with the known 4-hydroxy-6,7-methylenedioxy-1,2,3,4-tetrahydroisoquinoIine (439) (Scheme 62). Subsequent to protection of the amino group as the trifluoroacetyl derivative, the amide alcohol 440 was converted into the amide thioether 441, by reaction with phenylthiol in the presence of zinc iodide. Alkaline hydrolysis of 441,... 

The synthesis of A-arylindoles from A,A-diaryl-A -trifluoroacetyl enehydrazines, a process analogous to the Fischer indole synthesis, has been studied in various solvents, including water, and in solvent-free conditions. Solvent polarity, or presence, appears to have had little influence on the reaction course. The A-TFA group has been found to be necessary for efficient reaction, with less electron-withdrawing substituents giving slower reactions, and triflyl diverting the reaction course after the... 

Reactions with acetyl trifluoroacetate (ATFA) give mixtures of acetylated and trifluoroacetylated products. The reported figures refer to the a 3 acetylation ratios (S. Clementi and G. Marino, unpublished data). 

The only available data concern the effects of alkyl groups on the trifluoroacetylation reaction (Table XXVI). A methyl group in position 2 increases (taking into account the statistical factor) the reactivity of the other a position by a factor of 23.8 (compared with factors of 380 and 1720 observed in thiophene and furan, respectively).143... 

The nitrido complex was applied to the direct asymmetric animation with a silyl enol ether as a substrate. Although several examples for achiral aminations of silyl enol ethers have been reported [32], an asymmetric version of reagent-controlled reaction has not appeared except for the one recent example [33] and the diastereoselective reactions with silyl enol ethers having a chiral auxiliary [34], The amination, which is presumed to take place via an aziridine intermediate [5g, lid,32], proceeded smoothly to give the A-tosylated a-aminoketone in 76% yield with 48% ee. When the same silyl enol ether was treated with complex 15 under Carreira s condition, the TV-trifluoroacetylated a-aminoketone was obtained in 58 % yield with 79 % ee (Scheme 24). 

The most abundant reaction partner for trifluoroacetyl radical is molecular oxygen. The product of addition (equation 107) is trifluoracetylperoxy radical CF3C(0)02, which may be converted into trifluoroacetyloxy CF3C(0)0 in two ways. The dominant process in the upper atmosphere is likely to be reaction with nitric oxide (equation 108). The alternative would be self-reaction (equation 109), resulting in disproportionation. 

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