Trifluoroacetamide

Trifluoroacetamides are more stable toward nucleophiles than the corresponding esters and are easily formed from trifluoroacetic anhydride and the amine. The trifluoroacetyl group (Tfac) is slowly cleaved by aqueous or methanolic HQ, NH, or Ba(OH)2 solutions as well as by NaBHj in methanol (M.L. Wolfrom, 1967). 

Trifluoroethanol was first prepared by the catalytic reduction of trifluoroacetic anhydride [407-25-0] (58). Other methods iaclude the catalytic hydrogeaatioa of trifluoroacetamide [354-38-1] (59), the lithium aluminum hydride reductioa of trifluoroacetyl chloride [354-32-5] (60) or of trifluoroacetic acid or its esters (61,62), and the acetolysis of 2-chloro-l,l,l-trifluoroethane [75-88-7] followed by hydrolysis (60). More recently, the hydrogenation of... 

A,<9-Bis(trimethyIsilyl)trifluoroacetamide. The reagent is suitable for the silylation of carfjoxylic acids, alcohols, phenols, amides, and ureas. It has the advantage over bis(trimethylsilyl)acetamide in that the byproducts are more volatile. 

K2CO3 or Na2C03, MeOH, H2O, rt, 55-95% yield." Note that the trifluoroacetamide has been cleaved in the presence of a methyl ester, which illustrates the ease of hydrolysis of the trifluoroacetamide group. ... 

Bistrifluoroacetamide [407-24-9] M 209.1, m 85 , b 135-136 /744mm, 141 /760mm. Major impurity is trifluoroacetamide. Add trifluoroacetic anhydride, reflux for 2h and fractionate using a Vigreux column at atmospheric pressure. [J Chromatogr 7S 273 1973.]... 

Mg, MeOH, it, 13 h, 91% yield. Esters are cleaved selectively in the order p-nitrobenzoate > acetate > benzoate > pivaloate trifluoroacetamide. ... 

C6F5O2CCF3, Pyr, DMF, it, 45 min, 92-95% yield. This reagent converts amines to the trifluoroacetamide. ... 

In a study by Stresser and co-workers, the effect on tumor modulation by 227 has been investigated. HPLC on liver extracts from Fisher 344 rats revealed two major compounds, 3,3 -bisindolylmefliane (133) and a linear trimer, together with a < l(KX)-fold lower content of 4 in comparison with the two major substances. The HPLC isolate was derivatized with /V-methyl-/V-bis(trifluoroacetamide) that, upon MS detection, gave a compound identical to /V,W -ditrifluoroacetylindolo-[3,2-()]carbazole. The content of 4 in this system was estimated to be 0.(XKX)13% of the total dose of 227 given. Thus, it was concluded that the beneficial effect of oral distribution of 227 is due to the total content of derivatives formed (95MI5). 

Helquist s work on the use of diazomalonate in the synthesis of oxazoles has been extended to other diazocarbonyl compounds in our own laboratory.<92TL7769, 94T3761> Thus it was found that sulfonyl-, phosphonyl- and cyano-substituted diazoesters gave the corresponding 4-functionalised oxazoles 30 in acceptable yield (Scheme 20). In many cases the yield of oxazole was significantly improved by the use of rhodium(II) trifluoroacetamide as catalyst. The 4-cyano-oxazole 30 (R = Me, Z = CN) proved interesting in that it allowed the formation of a bis-oxazole 31 by a second rhodium catalysed reaction (Scheme 20). 

Whatever the exact mechanism, the rhodium(II) catalysed reaction of diazocarbonyl compounds with nitriles is a useful route to oxazoles. A further example from our own laboratory illustrates the use of the reaction in the synthesis of the oxazolylindole alkaloids pimprinine 43a, pimprinethine 43b, and WS-30581A 43c. Diazoacetylindole 42 reacted with simple nitriles in the presence of rhodium(ll) trifluoroacetamide to give the corresponding oxazoles, deprotection of which gave the natural products 43 (Scheme 24).<94S1021>... 

In 2005 [61], Overman and coworkers described the application of their oxazoline system 41 to synthetically attractive trifluoroacetimidates 44 (Fig. 23) forming trifluoroacetamides 45, which, in contrast to benzamides 40, can be readily transferred into free primary allylic amines. 

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... 

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