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Search for "triflic acid" in Full Text gives 87 result(s) in Beilstein Journal of Organic Chemistry.

Straightforward synthesis of a tetrasaccharide repeating unit corresponding to the O-antigen of Escherichia coli O16

  • Manas Jana and
  • Anup Kumar Misra

Beilstein J. Org. Chem. 2013, 9, 1757–1762, doi:10.3762/bjoc.9.203

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  • stereoselective glycosylation of compounds 2 and 3 in the presence of a combination of N-iodosuccinimide (NIS) and triflic acid (TfOH) [18][19], followed by the removal of the p-methoxybenzyl (PMB) group in a one-pot reaction [17] by tuning the reaction conditions furnished the disaccharide acceptor 6 in 76
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Published 28 Aug 2013

Glycosylation efficiencies on different solid supports using a hydrogenolysis-labile linker

  • Mayeul Collot,
  • Steffen Eller,
  • Markus Weishaupt and
  • Peter H. Seeberger

Beilstein J. Org. Chem. 2013, 9, 97–105, doi:10.3762/bjoc.9.13

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  • toluene. Thioglycoside 35 was activated with N-iodosuccinimide (NIS) and triflic acid (TfOH) in dichloromethane and dioxane. In order to establish optimal reaction conditions, temperatures ranging from −40 °C to 25 °C were screened and the reaction time was varied between 15 and 45 minutes. After
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Published 16 Jan 2013

Engineering of indole-based tethered biheterocyclic alkaloid meridianin into β-carboline-derived tetracyclic polyheterocycles via amino functionalization/6-endo cationic π-cyclization

  • Piyush K. Agarwal,
  • Meena D. Dathi,
  • Mohammad Saifuddin and
  • Bijoy Kundu

Beilstein J. Org. Chem. 2012, 8, 1901–1908, doi:10.3762/bjoc.8.220

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  • triflic acid and methanesulfonic acid (MSA), to facilitate π-cyclization, and progress of the reaction was monitored by TLC. Although no conversion was observed for 2a in the presence of MSA (Table 1, entry 5 and entry 6) in CH3CN and DMF at 80 °C and 120 °C, respectively, the presence of 2% triflic acid
  • in DMF (Table 1, entry 8) favored complete conversion of 2a into 9a in >87% purity based on HPLC. The crude product obtained after workup was purified by silica gel column chromatography with EtOAc/hexane as an eluent in 84% isolated yield. An increase or decrease in the concentration of triflic acid
  • was found to be detrimental (Table 1, entries 9–11). Similarly, switching solvents from DMF to ACN in the presence of 2% triflic acid reduced the yield to 27% (Table 1, entry 7). The scope and limitation of the strategy with substrate 2a and 2c was established by synthesizing 11 compounds based on
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Published 08 Nov 2012

Automated synthesis of sialylated oligosaccharides

  • Davide Esposito,
  • Mattan Hurevich,
  • Bastien Castagner,
  • Cheng-Chung Wang and
  • Peter H. Seeberger

Beilstein J. Org. Chem. 2012, 8, 1601–1609, doi:10.3762/bjoc.8.183

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  • semi-protected oligosaccharide. The automated synthesis of 20 (Scheme 3) started with the glycosylation of resin-bound linker 17 with glucosamine building block 18 (2 × 5 equiv) [5] in the presence of N-iodosuccinimide and triflic acid. Fluorenylmethoxycarbonyl (Fmoc) removal was followed by
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Published 21 Sep 2012

Organocatalytic C–H activation reactions

  • Subhas Chandra Pan

Beilstein J. Org. Chem. 2012, 8, 1374–1384, doi:10.3762/bjoc.8.159

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  • ][11]. Previously, only preformed imines were used for this purpose, and the reactions were mostly thermally controlled [12][13][14][15]. Seidel and co-workers found that the combination of triflic acid and ethanol provided an effective system for the formation of cyclic aminals (Scheme 1), whereas the
  • combination of para-toluenesulfonic acid (PTSA) and benzene was the optimum system for Akiyama and co-workers (Scheme 2). After evaluating different Lewis and Brønsted acids with their equivalents as well as different solvents, Seidel and co-workers found that 0.2 equivalents of triflic acid in ethanol under
  • reflux provided the maximum yield of the desired product 1. The reaction was examined with different amines and moderate to good yields (35–75%) were obtained (Scheme 1) [10]. In certain cases, a stoichiometric amount of triflic acid was required to obtain acceptable yields of the desired products
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Published 27 Aug 2012

Electrochemical generation of 2,3-oxazolidinone glycosyl triflates as an intermediate for stereoselective glycosylation

  • Toshiki Nokami,
  • Akito Shibuya,
  • Yoshihiro Saigusa,
  • Shino Manabe,
  • Yukishige Ito and
  • Jun-ichi Yoshida

Beilstein J. Org. Chem. 2012, 8, 456–460, doi:10.3762/bjoc.8.52

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  • temperatures. However, α-selectivity was observed in the absence of base at elevated reaction temperatures. In situ generated triflic acid promotes the isomerization of β-products to α-products. Keywords: amino sugar; anomerization; electrochemical oxidation; glycosylation; thioglycoside; Introduction
  • group, simply by changing the reaction conditions. In order to confirm that the anomerization of 8β to 8α could take place under the reaction conditions, we examined the acid-mediated isomerization of the β-isomer of disaccharide 8β to the α-isomer 8α (Scheme 2). Triflic acid (TfOH) must be generated in
  • limitations of the glycosylation reaction using electrochemically generated glycosyl triflates are in progress in our laboratory. 1H NMR spectrum of glycosyl triflate 2a. Electrochemical conversion of thioglycosides to glycosyl triflates. Triflic acid mediated isomerization of β-glycoside. 1H- and 13C NMR
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Published 28 Mar 2012
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  • of aqueous quenching and washing. Therefore, the development of alternative procedures that can reduce or eliminate the waste from the work-up procedure is highly needed. It was reported that adamantylation of aromatics promoted by strong organic acids, such as trifluoroacetic acid [18] and triflic
  • acid [19], could circumvent the drawbacks associated with using concentrated H2SO4. However, these strong organic protic acids are expensive and volatile, and thus their recovery poses many difficulties. Strongly acidic ion-exchange sulfonic acid resins have been extensively exploited as recyclable
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Published 08 Feb 2012
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  • benzyl azide with α,β-unsaturated imides. Using a strong Brønsted acid (triflic acid) to activate the electron deficient imide π-bond, high diastereoselection was observed provided that a 1,1,3,3-tetraisopropoxydisiloxanylidene group (TIPDS) is used to restrict the conformation of the central 1,3-anti
  • diol. This development provides a basis for a stereocontrolled approach to the aminopolyol core of (−)-zwittermicin A using a bidirectional synthesis strategy. Keywords: azide; bidirectional synthesis; cycloaddition; dialkoxydisiloxane; TIPDS; triazoline; triflic acid; zwittermicin A; Introduction
  • aminohydroxylations [6][7][8]. Triflic acid-promoted reaction of an alkyl azide with an α,β-unsaturated imide delivers a formal anti-aminohydroxylation product. We wondered whether azide–olefin functionalization could be used to prepare the complex aminopolyol core of zwittermicin A [9][10][11][12]. We were
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Published 20 Dec 2010

Shelf-stable electrophilic trifluoromethylating reagents: A brief historical perspective

  • Norio Shibata,
  • Andrej Matsnev and
  • Dominique Cahard

Beilstein J. Org. Chem. 2010, 6, No. 65, doi:10.3762/bjoc.6.65

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  • dicyanoalkylidenes and is now commercially available. We also disclosed an easy-access to extended Yagupolskii-Umemoto type reagents, S-(trifluoromethyl)thiophenium salts, through triflic acid-catalyzed intramolecular cyclization of o-ethynylaryltrifluoromethylsulfanes. A series of S-(trifluoromethyl)benzo[b
  • (or selenides) with m-chloroperbenzoic acid followed by cyclization of the corresponding sulfoxides (or selenoxides) either with triflic anhydride or by direct fluorination with 10% F2/N2 in the presence of one equivalent of triflic acid or HBF4 (Scheme 2). The tellurophenium salt 7 was synthesized in
  • compounds that are benzothiophenium salts rather than dibenzo analogs. Ortho-ethynylaryl- and alkyl-trifluoromethylsulfanes were cyclized under strong acidic conditions with triflic acid to give the corresponding sulfonium salts in 64–94% yields (Scheme 12). It should be noted, that in the presence of gold
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Published 16 Jun 2010
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  • glycosylations employing triflic acid/N-iodosuccinimide. Easily accessible selectively protected lactoside derivatives served as acceptor disaccharides to give the corresponding human milk pentasaccharides in good yields. These were characterized by spectroscopic means in the form of their peracetylated
  • target pentasaccharide. Conclusion In this contribution chemoenzymatically generated sialyl α,2-3- and sialyl α,2-6-glycosylated thiophenol 2-azido-lactose derivatives were employed as precursors for sialylated lactosaminide donor substituents in triflic acid/N-iodosuccinimide glycosylations. With easily
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Published 22 Feb 2010

Convenient method for preparing benzyl ethers and esters using 2-benzyloxypyridine

  • Susana S. Lopez and
  • Gregory B. Dudley

Beilstein J. Org. Chem. 2008, 4, No. 44, doi:10.3762/bjoc.4.44

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  • of benzyl trichloroacetimidate using triflic acid, except that alkylation under neutral conditions is compatible with acid- (and base-) sensitive substrates. Results and Discussion 2-Benzyloxypyridine was prepared in 97% yield by heating a mixture of benzyl alcohol, 2-chloropyridine (1.1 equiv), and
  • benzyl ethers is described using 2-benzyloxypyridine and methyl triflate in lieu of benzyl trichloroacetimidate and triflic acid. N-Methylation of 2-benzyloxypyridine gives rise to an active benzyl transfer reagent (1) in situ, presumably in much the same way as N-protonation activates benzyl
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Published 26 Nov 2008

Synthesis of crispine A analogues via an intramolecular Schmidt reaction

  • Ajoy Kapat,
  • Ponminor Senthil Kumar and
  • Sundarababu Baskaran

Beilstein J. Org. Chem. 2007, 3, No. 49, doi:10.1186/1860-5397-3-49

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  • indolizidine skeleton using azido-olefin as a key intermediate (Scheme 3). In this reaction, in addition to benzo[e]indolizidine A, a minor product B having the basic skeleton of crispine A was isolated in 28% yield. The intramolecular Schmidt reaction of azido-olefin in the presence of triflic acid proceeds
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Published 19 Dec 2007
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