TFMSA

The Phacm group is introduced by the same methodology as the Acm group [PhCH2C(0)NHCH20H, TFMSA]."... 

The Phacm group is stable to the following conditions DIEA-CH2CI2, TFA-CH2CI2, piperidine-DMF, 0.1 M TBAF-DMF, and DBU-DMF for 24 h at It to HF-anisole or / -cresol (9 1) at 0° for 1 h and to TFA-scavengers (phenol, HSCH2CH2SH, p-cresol, anisole) for 2 h at 25°. It is partially stable (>80%) to TFMSA-TFA-/ -cresol for 2 h at 25°. These stability characteristics make the group compatible with BOC- or Fmoc-based peptide synthesis. ... 

The dimethoxybenzyl group was used for backbone protection of the pseudopeptides of the form Xaai/r(CH2N)Gly (Xaa = amino acid). It is introduced by reductive alkylation with the aldehyde and NaCNBH3. Acidolysis with TFMSA in TFA/thioanisole is used to remove it from the amine, but the efficiency is dependent upon the peptide sequence. ... 

The Doc group, introduced with the chloroformate and either DMAP or /-BuOK, is quite acid stable, but can be cleaved with TFMSA-thioanisole-EDT-TFA (10 min, rt) or with / -cresol-HF (1 h, 0°). The Doc group was found to be suitable for tryptophan protection in /-Bu-based peptide synthesis, since no /-butylation of tryptophan was observed during acid deprotection. 

The 2-Adoc group is stable to TFA, but cleaved completely within 10 min with 25% HBr/AcOH, HF, and TFMSA/thioanisole/TFA. Under basic conditions, the group is slowly cleaved in 10% aq. TEA or 20% piperidine/DMF, but rapidly cleaved in 2 mol dm aq. NaOH. ... 

The cyclohexyl phosphate, used in the protection of phosphorylated serine derivatives, is introduced by the phosphoramidite method and cleaved with TFMSA/MTB/m-cresol/l,2-ethanedithiol/TFA, 4 h, 0° to rt. " ... 

I M TFMSA in TEA, thioanisole. Dibenzyl phosphates are only partially labile to TEA alone. 

From a phosphorothioate TFMSA, m-cresol, thiophenol, TFA. These conditions minimized the migration of the benzyl group to the thione. ... 

The relevance of Pt-OH formation to the change in the Tafel slope has been demonstrated by varying the content of water in the electrolyte [Murthi et al., 2004]. The experiments were performed in H20/trifluoromethanesulfonic acid (TFMSA) mixtures with several water/acid molar ratios. Whereas at high water contents the usual change in the Tafel slope from —112 to —59 mV/dec observed in aqueous solutions of H2SO4 and HCIO4 took place, at low water contents no change in the Tafel slope was observed. This corroborates the involvement of water in the formation... 

Figure 9.5 Anion adsorption on Pt in several electiolytes bisulfates and TFMSA as determined by radiotracers (RT), and OH and H as reflected in A/r, the ampUtiide of the XANES peak. The effect of 6 M TFMSA suppressing OH formation can be seen. (Reproduced with permission from Teliska et al. [2007].)...

The specific adsorption of bisulfate anions is observed in H2SO4 in both EXAFS and XANES data and, in agreement with voltammetry, is seen to impede oxygen adsorption. Significant specific anion adsorption was found in 6 M TFMSA, but not in 1 M TFMSA [Teliska et al., 2007]. As mentioned above, this specific anion adsorption suppresses OH adsorption (particularly the formation of subsurface O), causes the Pt nanoparticle to become more round, and weakens the Pt-Pt bonding at the smface. The specific anion adsorption becomes site-specific only after lateral interactions from other chemisorbed species such as OH force the anions to adsorb into specific sites. 

Anion adsorbability this increases in the sequence F CIO4 TFMSA < HSO4 - P04 < Cr < Br < r. 

Fluorenone derived linker 17 prepared in two steps was coupled to aminomethyl-PS via DIPCDI [21]. Due to the presence of an electron-withdrawing carboxamide group, the release of carboxylic acids from this support requires strong acids, such as trifluoromethanesulfonic acid (TFMSA) (Scheme 1). Insertion of an oxygen adjacent to the biphenyl rings to the fluorenone scaffold provides xanthene 18 handle [22]. The oxygen is strategically located to decrease the acid concentration required... 

The following procedure for creating the N-H fulleropyrrolidine is adapted from Maggini et al. (1994), Prato and Maggini (1998), and Prato et al. (1996). Extreme care should be taken when using TFMSA, as this acid is 30 times stronger than concentrated sulfuric acid. 

Remove the trityl-protecting group by dissolving the derivatized fulleropyrrolidine in 5 ml of dichloromethane in a fume hood and then adding 50 pi of TFMSA (caution ) with stirring. 

Scheme 10. Auxiliaries for Native Chemical Ligation without cysteine (TFMSA, trifluoromethane sulfonic acid).

Trifluoromethanesulfonic Acid (TFMSA) Electrolyte Janskiewicz, S., George, M. and Baker, B.S. Aqueous Sulfonic Acid Electrolvte Fuel Cell. Mational Fuel Cell Seminar Abstracts, June 21-23, 1977, Boston, Massachusetts, 103-106. 

Solvents and scavengers methylene chloride (DCM), trifluoroacetic acid (TFA), A,A-diisopropylethylamine (DIEA), 100% ethanol, iV,A-dimethylformamide, di-methylsulphoxide (DMSO), acetonitrile, trifluoromethanesulfonic acid (TFMSA), dimethylsulfide (DMS), p-cresol, dimercaptoethane. 

Remove the formyl- and benzyl-type protective groups from peptide side chains by using the low TFMSA method. Treat the resin with a mixture of TFMS A/TFA/ p-cresol/dimercaptoethane (10/50/30/8/2 v/v). Mix all the components on ice carefully adding TMFSA as the last step. Take 1 mL of mixture per 50 mg of peptide resin and mix on ice for 2 h. 

For acidic residues and Tyr, the Bzl protecting group is preferred. The cyclohexyl protecting group for Asp and Glu (preferred for HF cleavage conditions) was not removed under 10% TFMSA/TFA conditions, although at 40% TFMSA/TFA the cyclohexyl group was removed. 

The most problematic issue using the catechol safety-catch linker is the activation/ deprotection steps. Although best results are obtained with HF, for large libraries in our laboratory this was not possible. Therefore we tend to use TFMSA/DCM as the activation mixture. 

Fig. 7. Crude HPLC of Cyclo-[Phe-Asn-Val-(D)Glu-Ala-Gly]. HPLC A after one treatment of TFMSA/TFA/p-cresol. HPLC B after two treatments of TFMSA/TFA/ p-cresol. C = Cyclic peptide, Bzl = benzyl. Tit = Trityl, L = Linear.

A. Low-TFMSA Method This method is used mainly to deprotect the peptide-resin from the formyl group on Trp and benzyl types of protective groups. In order to avoid the side products, the procedure must be applied after the... 

Mix deprotection mixture (TMFS A/TFA/DMS/p-cresol/dimercaptoethane 10 50 30 8 2 vol.%) on ice. Stir solution and add TFMSA dropwise as a last step. 

The most dangerous solvents in SPPS when using t-Boc chemistry are hydrogen fluoride (HF) and trifluoroacetic acid (TFA). HF is extremely dangerous and requires a special HF apparatus of Teflon-coated vessels to be handled safely. TFA and TFMSA in contact with skin also cause wounds that take weeks to heal. 

With these preliminary theoretical results in mind, a set of three Co-based porphyrin electrocatalysts (from CoTMPP precursors pyrolized at 600, 700, and 800°C) were examined in situ (room temperature de-aerated IM TFMSA) at beamline X-llA at the NSLS. Standard EXAFS analysis was of limited use in determining the stmctural parameters due to the disordered nature of... 

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