Phenyl triflimide

The conditions using 2,4,6-collidine/Tf20 and having the reaction warm from -78 °C to 25 °C were chosen mainly to avoid using more expensive reagents such as 2,6-di-r-butyl-4-methylpyridine or A-phenyl triflimide. (a) Stang, P. J. Hanack, M. C. Subramanian, L. R. Synthesis 1982, 85. (b) McMurray, J. E. Scott, W. J. Tetrahedron Lett. 1983,24,979. 

A unique class of steroidal alkaloids, the batrachotoxinins, is isolated in small quantities from the skins of poison arrow frogs and also from the feather of a New Guinea bird. One of the key steps during the total synthesis of (+)-batrachotoxinin A by Y. Kishi et al. was a Michael addition to form a seven-membered oxazapane ring. The removal of the primary TBS protecting group was achieved by treatment with TASF and the resulting alkoxide attacked the enone at the 3-position to afford an enolate as the Michael adduct. The enolate was trapped with phenyl triflimide as the end triflate. 

Treatment of -caprolactone with 7V,7V-bis(trimethylsilyl)lithium amide and then with A-phenyl triflimide affords 2-triflyloxy-2-hexenolide (22). The latter is obtained in 89% yield <89CL1313> and can be regarded as a key intermediate in the syntheses of diverse 2-substituted 4,5,6,7-tetra-hydrooxepines. For instance, reactions of (22) with lithium dialkyl- or diphenylcuprates result in 2-butyl-substituted derivatives (23 R = Aik, Ph) <89CL1313>, while analogous interaction with hexa-methyldistannane gives 2-trimethylstannyl-4,5,6,7-tetrahydrooxepin (23 R = SnMcj) <91SL197>. 

Enol triflates, which can easily be prepared by trapping regiospecilically generated enolates with triflic anhydride or 7V-phenyl triflimide, have also been applied in car-bopalladation reactions of allenes (Scheme... 

Many stannane reagents are commercially available, or they can be readily synthesized via reaction between a Grignard reagent and tri- -butyl tin chloride. The reactants that most commonly react with the transmetallated group are a vinyl triflate (C=C—OSO2CF3) and a vinyl iodide. Vinyl triflates are prepared from the reaction of an enolate with N-phenyl triflimide (PhNTfj, Tf = SOjCFj). 

Benzylamine allowed to react at room temp, with N-benzoyl-N-phenyltriflamide in methylene chloride N-benzoylbenzylamine. Y 98%. F. e., also with phenyl triflimide, CeH5N(S02CF3)2, s. J. B. Hendrickson and R. Bergeron, Tetrah. Let. 1973, 4607. 

DesMarteau and coworkers reported the preparation, X-ray crystal structure and chemistry of trifluo-roethyliodonium salts 391 by the reaction of fluoroalkyliodo-bis(trifluoroacetates) 389 with benzene and triflimide acid (390) (Scheme 2.113) [68,531,532], The structure of trifluoroethyl(phenyl)iodonium salt 391 (n = 1) was established by a single-crystal X-ray analysis [68], In contrast to fluoroalkyliodonium triflates 383, compounds 391 are stable to water and can be used as reagents for fluoroalkylation reactions in aqueous media. 

To avoid some competitive side reactions, Yamamoto recently reported that highly reactive intermediate can be stabilized by the coordination of bulky Lewis acid (Scheme 6.102). That is, bis(2,6-diphenylphenoxide) aluminum triflimide, as a sterically bulky Lewis acid, efficiently catalyzed [2 + 2]cycloaddition of phenyl acrylate with tris(trimethylsilyl)silyl enol ethers to give cycloadducts with high diastereoselectivity [121]. 

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