Amines trifluoromethanesulfonic anhydride

Electrocyclization is the key step in a route to 4//-imidazoles 1187 and imidazoles 1188. Thus, activation of AT-acylamidines 1183 with trifluoromethanesulfonic anhydride and subsequent condensation with amino compounds 1185 produces l-amino-2,4-diazapenta-l,3-dienes 1186. Deprotonation of 1186 by the use of strong organic bases yields the corresponding 4//-imidazoles 1187 or imidazoles 1188 after amine elimination through an anionic 1,5-electrocyclization reaction. For the cyclization to occur, the amino compound 1185 needs to possess electron-withdrawing substituents such as alkoxycarbonyl or fluorenyl groups (Scheme 290) <2004EJO2567>. 

The C-4 acids (183 and 184) have also been subjected to borane reduction conditions to afford alcohol 195 in 23-50% yield or 64% yield as the C-8 epimeric mixture (195 and 196, Scheme 29) [34, 49, 64]. The C-8 alcohol epimers 195 and 196 have been treated separately as a common intermediate for a number of C-4 derivatives including esters, ethers, and amines [34, 49, 64], Alcohols 195 and 196 was subjected to DCC, DMAP, and desired acid chloride or carboxylic acid in CH2CI2 affording ester analogs in 50-92% yield [64], Esters prepared include alkyl, aryl, and fluorenylmethyloxycarbonyl (Fmoc) protected amino acid derivatives (197 and 198) [64]. Ethers were prepared with various alkyl halides and Ag20 in CH3CN at 40 °C. Alkyl, allyl, and benzyl ethers were prepared in 45-80% yield (199 and 200) [34,64]. Alcohols 195 and 196 were then activated to the triflates and displaced by a variety of amines by treatment with trifluoromethanesulfonic anhydride and desired amine in 22% - quantitative yield over two steps (201 and 202)... 

Trifluoromethanesulfonic acid anhydride, bp 84°C, is prepared by refluxing the acid over an excess of phosphorous pentoxide (18,26). The anhydride reacts instantaneously with ammonia or amines to form trifluoromethanesulfonamides. The anhydride reacts with most polar organic solvents. 

Amides of trifluoromethanesulfonic acid (triflamides) can be prepared by the reaction of the corresponding amines with triflic anhydride The most applicable in organic synthesis are iV-phenyltriflamides, which can be used as mild and selective Inflating reagents [110, lll ... 

Mercury(II) trifluoromethanesulfonate-N,N-Dimethylaniline (1). The reagent is prepared by reaction of triflic anhydride with yellow HgO in nitromethane with stirring for 18 hours. Then the amine is added, and a clear pale yellow solution is formed. 

Aniline allowed to react at -78° with trifluoromethanesulfonic acid anhydride and triethylamine in methylene diloride -> N-phenyltriflamide. Y 97%. - The protective group can be removed by reduction. F. e. and triflating agent, also Gabriel-type synthesis of prim, amines from halides via triflamides, s. J. B. Hendrickson and R. Bergeron, Tetrah. Let. 1973, 3839. 

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