Triflates tris

Thus, beyond the seminal contributions on deaminations, side reactions were found to most frequently occur in attempted sulfonate displacements when poor nucleophiles, especially fluoride, or the conditions of solvolysis were applied. In this way, impetus for the development of better LGs, represented by trifiuoro-methanesulfonates (triflates) and imidazolesulfonates (imidazylates), as well as more powerful nucleophiles, e.g., tetraalkylammonium salts, was added. In the case of intended fluorinations, the classical sulfonate/fluoride tandem [usually triflate/tetrabutylammonium fluoride (TBAF) or triflate/tris(dimethylamino)... 

The coupling of the enol triflate 703 with the vinylstannane 704[397] has been applied to the synthesis of glycinoeclepin[576]. The introduction of a (Z)-propenyl group in the / -lactam derivative 705 proceeds by use of tri-2-furylphosphine[577]. However, later a smooth reaction to give the propenyl-iactam in 82% yield was achieved simply by treating with Pd(OAc)2 in NMP or CH2CI2 for 3-5 min without addition of LiCI and the phosphine ligand[578]. 

Tri.-nethylsilyl triflate (TMSOTf), PhSCH, CF3COOH. These conditions also cleave the following protective groups used in peptide synthesis (MeO)Z-, Bn-, Ts-, CI2C6H3CH2-, BOM (benzyloxymethyl)-, Mts-, MBS-, r-Bu-SR, Ad-SR, but not a BnSR, Acm, or Arg(N02) group. The rate of cleavage is reported to be faster than with TfOH/TFA. 

In view of this behavior, the next step involved a search for an anionic sohd that was more similar to triflate. Several organic polymers with sulfonic groups were tried as supports [52]. Dowex and Deloxan were used as supports for the enf-6a-Cu(II) complex. The solid catalysts were used in the same cyclopropanation reaction (Scheme 7) and some relevant results are gathered in... 

Bismuth tra-tri lluoromcthancsulfonate, Bi(OTf)3, and BiCh were found to be effective catalysts for the Friedel-Crafts acylation of both activated and deactivated benzene derivatives such as fluorobenzene.19 Ga(III) triflate is also effective for Friedel-Crafts alkylation and acylation in alcohols and can tolerate water.20 This catalyst is water-stable... 

Namely, allyl alcohol is successively treated with diethylzinc, (R,R) dipropyl tartrate, and 4-methoxybenzohydroximinoyl chloride (163) to afford the enantiomeric isoxazoline alcohol 166, which under the Jones oxidation conditions affords the corresponding carboxylic acid derivative (167). Treatment of compound 167 with hydroxylamine-O-triflate followed by tri-fluoroacetic acid gives rise to the desired enantiomeric 165 in high excess enantiomeric yield. The synthesis of other isosteric analogues of 165 was reported in the same paper. None of the isosteric analogues exhibits LpxC inhibitory and antibacterial activities [103]. 

Martin et al. have developed a unique series of capped tris(l,2-di-aminoethane) cages which can encapsulate divalent transition metal ions in a near octahedral geometry (28). The iron(II) complex with the ligand (NH2)2sar turns out to be a crossover system in solution [34], but the solid triflate salt is low-spin [43]. This is the only Fe(II) crossover system having 6 identical aliphatic nitrogen donors. 

The aldol reactions introduced thus far have been performed under basic conditions where enolate species are involved as the reactive intermediate. In contrast to the commonly accepted carbon-anion chemistry, Mukaiyama developed another practical method in which enol species can be used as the key intermediates. He is the first chemist to successfully demonstrate that acid-catalyzed aldol reactions using Lewis acid (such as TiCU) and silyl enol ether as a stable enol equivalent can work as well.17 Furthermore, he developed the boron tri-fluoromethane sulfonate (triflate)-mediated aldol reactions via the formation of formyl enol ethers. 

Glycosylation of 3-amino-5(7)//-[l,2,4]triazolo[4,3-3] l,2,4 triazole 17 with 1-O-acetyl- 2,3,5-tri-O-benzoyl-D-ribo-furanose 18 or 2,3,5-tri-O-benzoyl-D-ribofuranosyl bromide 19 can be selective or nonselective, depending on the reaction conditions (Scheme 1). In the presence of trimethylsilyl triflate or boron trifluoride etherate, the... 

Some N-glycosides have been synthesized as nucleoside analogues by Vilarrasa and co-workers <1996TL901>, the result is shown in Scheme 8. The starting compound, [l,2,4]triazolo[5,l-c][l,2,4]triazine-4(l//)-one 54, was reacted with tri-0-benzoyl-/3-diribofuranosyl bromide under two different reaction conditions. In the presence of silver triflate at low temperature, the zwitterionic 2-substituted compound 55 was obtained, whereas under reflux conditions in acetonitrile the neutral 1-substituted compound 56 was formed. 

Boron tris(trifluoromethanesulfonate). This triflate is obtained by reaction of BC1, with triflic acid in S02C1F at -78°. Distillation at reduced pressure provides a solid, m. p. 45°, b. p. 68-73°/0.5 mm. It is extremely hygroscopic, and is soluble m CRiC, CHjNOi, CH CN. Aluminum and gallium triflate are poorly soluble in the common solvents. All three triflates can function as Friedel-Crafts catalysts, but the boron triflate is the most effective as a soluble catalyst. ... 

Indeed, a variety of Lewis acids have been shown to effed glycosylation with hemiacetal donors. Ernst and coworkers have used 5mol% of [Rh(III)(MeCN)3 (triphos)] tris(triflate) with 4 A molecular sieves to prepare glycoconjugates 18 and 19 [26]. Mukaiyama s group has used trityl tetrakis(pentafluorophenyl)borate (3-5 mol%) with Drierite in the preparation of disaccharides 20 and 21 [27,28]. In the synthesis of 21, the a-seledivity was shown to arise from in situ anomerization of the (1-pyranoside over time. 

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