Trifluoromethanesulfonate CF3O3S- - PubChe

Efficient, trimethylsilyl triflate-mediated conversion of Diels-Alder adducts of 1-methoxy-3-[(trimethylsilyl) oxy]-1, 3-butadiene (Danishefsky's diene) to Methyl trifluoromethanesulfonate, also commonly called methyl triflate and abbreviated MeOTf, is the organic compound with the formula CF 3 SO 2 OCH 3. It is a Triflate. Triflates have also been used to convert primary amines into reactive leaving groups for nucleo-philic substitution. From: Comprehensive Organic Functional Ceric triflate. Cerium(IV) triflate. SDS Certificate of Analysis Technical Inquiry Stock No. Size Price ($) Quantity Availability; L20056-06: 5g: 43.80: L20056-14: The triflate moiety 106 was found to be an acceptable leaving group for displacement reactions. The addition of DMPU as a co-solvent prior to the addition of the

Triflat - Wikipedi

Solid polymeric electrolyte of poly(ethylene)oxide-50% epoxidized natural rubber-lithium

The mechanism for the addition of a triflate group to an alcohol. The triflate group is added by using trifluoromethanesulfonyl chloride. Due to the high ele.. dict.cc | Übersetzungen für 'triflate' im Englisch-Deutsch-Wörterbuch, mit echten Sprachaufnahmen, Illustrationen, Beugungsformen,. Silver triflate.png 537 × 239; 7 KB. Silver-triflate-3D-vdW.png. Synthese von Bicyclo(4.2.0)octan.svg 425 × 55; 24 KB. Synthese von gamma-Lactonen aus ungesättigten Triflate, more formally known as trifluoromethanesulfonate, is a functional group with the formula CF 3 SO 3-.The triflate group is often represented by -OTf, as

Triflate - Lexikon der Chemie - Spektrum

  1. Finden Sie Hohe Qualität Triflate Hersteller Triflate Lieferanten und Triflate Produkte zum besten Preis auf Alibaba.co
  2. The RDFs from triflate ion/water mixtures shows that increasing hydration causes water molecules to orient around the SO 3 − group of triflate ions, solvate the
  3. Traductions en contexte de triflate en anglais-français avec Reverso Context : The method is applicable to a wide variety of aryl triflate substrates having
  4. Copper (II) triflate is the copper (II) salt of trifluoromethanesulfonic acid (known simply as triflic acid) which has a chemical formula of Cu (OSO 2 CF 3) 2. This
  5. Stimulation of Toll-like receptor 4 (TLR4) by lipopolysaccharide (LPS) triggers myeloid differentiation factor 88 (MyD88)-dependent early-phase NF-kappaB activation

Triflate Sigma-Aldric

  1. Sancai Industry Co.,Ltd. ist Lieferant für Mannose triflate. tätig. Wir können auch Chemikalien für unsere Kunden anpassen. Durch die Nutzung innovativer Technologien
  2. Holen Sie sich nur die beste Qualität trimethylsilyl triflate und alle ähnlichen Dinge nur bei Alibaba.com. trimethylsilyl triflate kann in einer Vielzahl von
  3. The reaction with allyl triflate requires the use of the 5-chloromercurinucleoside. La réaction avec le triflate d'allyle nécessite l'utilisation du
  4. triflate Übersetzung, Französisch - Deutsch Wörterbuch, Siehe auch 'triplace',triplite',triage',triplé', biespiele, konjugatio

What does TRIFLATE stand for? List of 1 TRIFLATE definition. Top TRIFLATE abbreviation meaning updated March 202 O-Aminodihydroartemisinin was synthesized for the first time via TMS triflate catalyzed coupling reaction of O-acetylartemisinin. The reaction proceeds with high yield without losing the endoperoxide of the artemisinin backbone. The new coupling reaction was employed to prepare artemisinin O-glycosi Fluorination of boronic acids mediated by silver(I) triflate Org Lett. 2009 Jul 2;11(13):2860-3. doi: 10.1021/ol901113t. Authors Takeru Furuya 1 , Tobias Ritter. Affiliation 1 Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA. PMID: 19507870 DOI: 10. The RDFs from triflate ion/water mixtures shows that increasing hydration causes water molecules to orient around the SO 3 − group of triflate ions, solvate the hydronium ions, and other water molecules. The diffusion of triflate ions, hydronium ion, and water molecules shows an increase with hydration. At λ = 1, the diffusion of triflate ion is 30 times lower than the diffusion of triflic. Die CLP-Verordnung gewährleistet, dass Arbeitnehmer und Verbraucher in der Europäischen Union durch die Einstufung und Kennzeichnung von Chemikalien eindeutig über die mit Chemikalien verbundenen Gefahren informiert werden

Trifluormethansulfonsäure - Wikipedi

B. 3-Methyl-2-buten-2-yl triflate. A solution of 2.58 g. (0.0300 mole) of 3-methyl-2-butanone (Note 4) and 2.78 g. (0.0352 mole) of anhydrous pyridine (Note 5) in 10 ml. of anhydrous n-pentane (Note 6) is placed in a dry, 50-ml. Erlenmeyer flask, and the flask is stoppered with a rubber septum.After the solution has been cooled in an acetone-dry ice cooling bath, 9.72 g InChI=1S/CHF3O3S/c2-1 (3,4)8 (5,6)7/h (H,5,6,7) InChIKey. ITMCEJHCFYSIIV-UHFFFAOYSA-N Google Search. Mol Weight. 150.07 g/mol. Molecular Formula. CHF3O3S. Exact Mass. 149.959851 g/mol

Trimethylsilyl trifluoromethanesulfonate C4H9F3O3SSi

triflate - Deutsch-Übersetzung - Linguee Wörterbuc

Tetrakisacetonitrile Copper (I) Triflate - also known as Tetrakis (acetonitrile)copper (I) Trifluoromethanesulfonate - is one of numerous organometallic compounds manufactured by American Elements under the trade name AE Organometallics™. Organometallics are useful reagents, catalysts, and precursor materials with applications in thin film. The stereoselectivity and stereospecificity of the triflate-mediated intramolecular Schmidt reaction of substituted 3-(1-azidocyclohexyl)propanol derivatives leading to octahydro-1H-pyrrolo[1,2-a]azepine, the structural skeleton of several important families of alkaloids such as the Stemona alkaloids, has been examined Traductions en contexte de triflate en anglais-français avec Reverso Context : The method is applicable to a wide variety of aryl triflate substrates having variations in both electronic and steric properties 98%+ Ytterbium(III) triflate/Ybotf3 CAS#54761-04-5 | Jenny. 98%+ Ytterbium(III) triflate/Ybotf3 CAS#54761-04-5 | Jenny. Skip to content. Home; Products. Biochemical industry. Peptides. Beauty peptide; Drug peptides; Small molecules Peptides; Customized peptides; Amino acids and their derivatives. Chiral amino acid series; Food additives series ; Peptide series; Biochemical reagents and.

Trimethylsilyl trifluoromethanesulfonate 99% 27607-77-

  1. Many translated example sentences containing triflate - German-English dictionary and search engine for German translations
  2. Sancai Industry Co.,Ltd. ist Lieferant für Mannose triflate. tätig. Wir können auch Chemikalien für unsere Kunden anpassen. Durch die Nutzung innovativer Technologien und hervorragender Talente und durch mehr als 15 Jahre Entwicklung haben wir gute Ergebnisse erzielt Beziehung zu Kunden im In- und Ausland. Um auf dem Markt wettbewerbsfähig.
  3. 2.3 Lithium Triflate Market Share by Company Type (Tier 1, Tier 2 and Tier 3) 2.4 Global Lithium Triflate Average Price by Manufacturers (2016-2021) 2.5 Manufacturers Lithium Triflate Production Sites, Area Served, Product Types 2.6 Lithium Triflate Market Competitive Situation and Trends 2.6.1 Lithium Triflate Market Concentration Rat
  4. ium triflate covalently grafted over MCM-41 (Al(TF)-MS catalyst) was synthesized by a novel route, ai

This video shows you how to pronounce Triflate Buy Tetrakisacetonitrile copper(I) triflate, a biochemical for proteomics research, from Santa Cruz Biotechnology. MF: CuC8N4H12•CF3SO A solvent- and halogen-free synthesis of high purity triflate ionic liquids via direct alkylation of organic bases (amines, phosphines or heterocyclic compounds) with methyl and ethyl trifluoromethanesulfonate (methyl and ethyl triflate) has been developed. Cheap and non-toxic dimethyl and diethyl carbonate serve as source for the methyl and ethyl groups in the preparation of methyl and ethyl. Verwandte Reaktionen: Hiyama-Kupplung, Stille-Kupplung, Ullmann-Synthese, Miyaura-Borylierung Organic Chemistry Portal: Suzuki Coupling Suzuki-Kupplung. Die Suzuki-Kupplung ist eine Palladium-katalysierte Kreuzkupplung zwischen Organoboronsäuren und Arylhalogeniden Seven triflate salts differ from mild to strong p-dopant on poly(3hexylthiophene) sensing micro-arrays. Each material shows a pattern of conductance modulation for the polymer which is reversible, reproducible, and distinctive of other gas exposures. Based on principal component analysis, an array doped with only two different triflates can be trained to reliably discriminate gases, which re.

Methyl trifluoromethanesulfonate - Wikipedi

Triflate anions preferentially approach the ammonium cation so as to form strong hydrogen bonds between sulfonate oxygen atoms and the acidic ammonium hydrogen. The ionic conductivity was somewhat underestimated, especially at lower temperatures. Analysis of conductivity data suggests that there is significant correlated motion of oppositely charged ions in these PILs, especially at short. Was sind die Thesauren des Wortes triflate? Sie können herausfinden, alle Thesauri des Wortes triflate in Wordow. Wie Sie sehen können, nicht nur Synonyme und Antonyme, aber auch Hypernyme, Hyponyme, Meronyme, Anagramme, Holonyme, Redewendungen Sätze, homorhyme, Homophone, Präfixe und Suffixee in Wordow sehen. Another Words of triflateAllgemein gesprochen kann dieses wort triflate in. Polymeric membranes to be used as electrolytic separators in lithium batteries were prepared from Poly Ethylene Oxide (PEO) and Lithium Triflate salt (LiTf) via a solventfree procedure. Several membranes, having different PEO/LiTf molar ratios, were characterized by Electrochemical Impedance Spectroscopy (EIS) to obtain their ionic conductivity. Most of the compositions exhibit an Arrhenius. dict.cc | Übersetzungen für 'triflate' im Französisch-Deutsch-Wörterbuch, mit echten Sprachaufnahmen, Illustrationen, Beugungsformen,.

Triflate - an overview ScienceDirect Topic

Global Methyl Triflate Market Growth 2020-2025 report is published on April 13, 2020 and has 133 pages in it. This market research report provides information about Manufacturing (Chemicals), Chemicals industry. It covers Global market data and forecasts. It is priced starting a dict.cc | Übersetzungen für 'triflate' im Kroatisch-Deutsch-Wörterbuch, mit echten Sprachaufnahmen, Illustrationen, Beugungsformen,. dict.cc | Übersetzungen für 'triflate' im Rumänisch-Deutsch-Wörterbuch, mit echten Sprachaufnahmen, Illustrationen, Beugungsformen,. triflate translation in English-French dictionary. Cookies help us deliver our services. By using our services, you agree to our use of cookies

The reaction with allyl triflate requires the use of the 5-chloromercurinucleoside. La réaction avec le triflate d'allyle nécessite l'utilisation du 5-chloromercurinucléoside. (organic chemistry) Any salt or ester of trifluoromethanesulfonic acid. Any salt or ester of trifluoromethanesulfonic acid Show declension of triflate ( ) Similar phrases in dictionary English French. (1. dict.cc | Übersetzungen für 'triflate' im Spanisch-Deutsch-Wörterbuch, mit echten Sprachaufnahmen, Illustrationen, Beugungsformen,. triflate. triflate: translation. triflatas statusas T sritis chemija formul ė CF₃SO₃(M,R) atitikmenys: angl. triflate rus. трифлат ryšiai: sinonimas - trifluormetansulfonatas. Chemijos terminų aiškinamasis žodynas - 2-asis patais. ir papild. leid. - Vilnius: Mokslo ir enciklopedijų leidybos institutas. Kazys Daukšas, Jurgis Barkauskas, Vitas Daukšas. 2003.. GHIT E T A L. | 3 molecule mitochondrial anti-viral signaling protein (MAVS) (Hou et al., 2011). Triggering of MAVS induces activation of the transcrip <i>Purpose</i>. We hypothesized that innate immune response pathways might be involved in thyroid carcinogenesis. To investigate this hypothesis, we aimed at analyzing the expression of several receptors and molecules in the innate immune system in papillary thyroid carcinoma (PTC) and anaplastic thyroid carcinoma (ATC) tissues. <i>Methods</i>. Of the surgically resected specimens, 11 ATC.

107792-63-2 - Cerium(IV) trifluoromethanesulfonate, 98%

  1. dehydrosulfurization of aromatic thioamides to nitriles file.scirp.org/pdf/ijoc_ journal of organic..
  2. L'ion triflate ou trifluorométhylsulfonate CF 3 SO 3-est la base conjuguée de l'acide trifluorométhanesulfonique (acide triflique) CF 3 SO 3 H (abrégé TfOH), un superacide mille fois plus fort que l'acide sulfurique concentré. Ces deux espèces ont la faculté de résister aux réactions d'oxydo-réduction. L'anion triflate est un nucléophile très faible
  3. Lithium triflate (LIOTF) is a water-soluble powder with excellent electrochemical performance, high temperature resistance and chemical stability. It is commonly used in electrolyte, antistatic, conductive additives and ionic liquids, etc. Welcome to call +86 21-6419685
  4. TF abbreviation stands for Triflate. All Acronyms. Search options. Acronym Meaning; How to Abbreviate; List of Abbreviations; Popular categories. Business; Medical; Military; Slang; Technology; Clear; Suggest. TF means Triflate. Abbreviation is mostly used in categories: Organic Chemistry. Rating: 3. 3 votes. What does TF mean? TF stands for Triflate (also Task Force and 1090 more) Rating: 3.
  5. gton, IL 61701, USA, Fax: (internat.) + 1-309/556-3864 . Search for more papers by this author. Phillip L. Butler, Laboratory for Environment Friendly.
  6. Triflate Silver trifluoromethanesulfonate Wedding Information, silver, angle, white, text png 1200x605px 30.92KB; Dibutylboron trifluoromethanesulfonate Triflate Organic chemistry Reagent, others, angle, white, text png 1280x830px 26.34KB; Scandium(III) trifluoromethanesulfonate Triflate Scandium oxide Lewis acids and bases, 3d model, natural Foods, food, chemistry png 1100x850px 555.91KB.

Triflates - an overview ScienceDirect Topic

triflate Übersetzung, Französisch - Französisch Wörterbuch, Siehe auch 'trilatère',trilame',trilatéral',triflore', biespiele, konjugatio Lithium Triflate CAS 33454-82-9, Find Details about 33454-82-9, CAS 33454-82-9 from Lithium Triflate CAS 33454-82-9 - Shandong Zhi Shang Chemical Co., Ltd. Product Info. Sign In Join Free. Home. Quotations. Associates. Favorites. Contact Us App. Clear History; Overview . Product Details . Recommended . Watching this video will consume data if you are not using WI-FI. Video unavailable. Please. •Häufig Triflate als Abgangsgruppe •Hydrolyselabil, Verwendung von Tosylaten als stabilere und billigere Alternative. Nickelkatalysierte Kreuzkupplungen •Kreuzkupplung mit elektronisch deaktivierten Chlor- und sogar Fluorarenen möglich •Bindungsdissoziationsenergien von Ph-F 528 kJ/mol Ph-Cl 402 kJ/mol Ph-Br 339 kJ/mol Ph-I 272 kJ/mol. Nickelkatalysierte Kreuzkupplungen. Triflate, also known by the systematic name trifluoromethanesulfonate, is a functional group with the formula CF 3 SO 3 −. The triflate group is often represented by −OTf, as opposed to −Tf ().For example, n-butyl triflate can be written as CH 3 CH 2 CH 2 CH 2 OTf. The corresponding triflate anion, CF 3 SO − 3, is an extremely stable polyatomic ion; this comes from the fact that.

Triflate ion CF3O3S ChemSpide

Triflate salts. Triflate salts are thermally very stable with melting points up to 350 °C for sodium, boron and silver salts especially in water-free form. They can be obtained directly from triflic acid and the metal hydroxide or metal carbonate in water. Alternatively, they can be obtained from reacting metal chlorides with neat triflic acid or silver triflate, or from reacting barium. triflate name meaning available! triflate name numerology is 1 and here you can learn how to pronounce triflate, triflate origin and similar names to triflate name Triflate, tosylate, and mesylate ions are excellent leaving groups, because the sulfonate ions can stabilize the negative charge via resonance. Good leaving groups are weak bases. These ions are weak bases because they are the conjugate bases of very strong sulfonic acids. But the halide ions Cl⁻, Br⁻, and I⁻ are also good leaving groups. Seven triflate salts differ from mild to strong p-dopant on poly(3-hexylthiophene) sensing micro-arrays. Each material shows a pattern of conductance modulation for the polymer which is reversible, reproducible, and distinctive of other gas exposures. Based on principal component analysis, an array doped with only two different triflates can be trained to reliably discriminate gases, which re. In this study the potential of 1-(difluoromethyl)-3-methyl-4-phenyl-1H-1,2,3-triazol-3-ium triflate as precursor for the synthesis of the [18 F]trifluoromethylation building block [18 F]fluoroform with high molar activity was investigated. The triazolium precursor was reacted under various conditions with [18 F]fluoride, providing [18 F]fluoroform with radiochemical yields (RCY) and molar.

1-Ethyl-3-methylimidazolium triflate, 99% IoLiTe

Indium(III) triflate, a trivalent indium reagent, was shown to be a highly-efficient catalyst for the conversion of primary amides to the corresponding nitriles. The successful reactions required 5 mol% of indium(III) triflate, and toluene was proved to be the most suitable solvent. Various amides were subjected to this method, and each produced the corresponding nitriles in excellent yields n Dioxolane is used in the production of lithium triflate and lithium iodide based electrolyte solutions for primary (single use) lithium batteries and as a solvent for removing photomasking compounds in the production of printed circuit boards. Very low water and ultra high purity grade Antonym des triflate. Nearby Words. trifle trifle away trifler trifles trifle with trifling tries to tries triers trier tried to tried-and-true. Synonym des triflate triflate Idiom. Languages. Synonym of triflate Antonym of triflate Sinonimo di triflate Contrario di triflate Sinônimo de triflate Antonym de triflate Sinónimo de triflate Antonino de triflate Synonyme de triflate Antonym de.

The Smith Synthesis of (-)-Nodulisporic Acid D

Triflate, triflic Acid, lewis Acids And Bases, gallium, Lien, researcher, Catalysis, permanent, pour, Chemical synthesis, chemical Reaction, chemical Structur In the coupling of bromobenzene with 4-methoxyphenyl triflate (Table 1, entry 1), 89% of substrate 2 was consumed at 24 hours, producing a 62% yield of product 3

1-Methyl-3-octylimidazolium triflate, 99% IoLiTe

Triflate (1) solvent effect. C H D Pd d + Sn d + R 3 L Ph C O Cl d-S E 2 open pathway: reasonable mechanism for inversion First stille proposed intermediate Espinet et al. proposed intermediate ・Associative pathway ・HMPA coordinated intermediate ・The bridging ability of HMPA is poor. Sn nBu 3 H D Cl O Ph CH 2 Pd (PPh 3) 2 Cl (4m o l %) HMPA , 65 ° C > 65% inversion D H O Espinet, P. et. We use terahertz (THz) transmission spectroscopy to obtain the frequency dependent complex dielectric functions for pure acetonitrile, pure 1-ethyl-3-methylimidazolium triflate (emim triflate, a room temperature molten salt), and mixtures of the two liquids Nicotinamide Riboside Triflate Nr, supplied by NovAliX, used in various techniques. Bioz Stars score: 86/100, based on 1 PubMed citations. ZERO BIAS - scores, article reviews, protocol conditions and mor

T1 - A simple loop method for the automated preparation of [11C]raclopride from [11C]methyl triflate. AU - Iwata, R. AU - Pascali, C. AU - Bogni, A. AU - Miyake, Y. AU - Yanai, K. AU - Ido, T. PY - 2001. Y1 - 2001. N2 - A simple automated preparation of [11C]raclopride by reaction of [11C]methyl triflate with demethylraclopride triflate is. The triflate 8-1 was prepared in high yield by the counteranion replacement reaction developed by Umemoto and co-worker . The fluorinating power of triflate 8-1 was the same as that of the fluoride 6-1 , but its nonhygroscopic nature made it a useful fluorinating agent in terms of handling and storage triflate-related ligands such as ethyl sulfate and bistriflimide, the additional dicoordinate copper complexes RCuOSO 3Et (2), [RCu(THF)][Cu(NTf 2) 2] (3) and RCuNTf 2 (4) could be isolated. Spectroscopic indications corroborate more CuI than CuII character in all RCuX derivatives. Recently, our group introduced a bulky substituent based on the carbazole scaffold and demonstrated its utility.

Adding Triflate Group Mechanism Organic Chemistry - YouTub

Die Salze der Schwefelsäure sind die Sulfate.Sie kommen teilweise in der Natur vor oder werden z. B. durch Umsetzung von Schwefelsäure mit Metallhydroxiden bzw. andere industrielle Prozesse gezielt hergestellt.Viele Sulfate finden Anwendung in der Technik, Medizin, Landwirtschaft und im Haushalt. Eines der wichtigsten Sulfate ist Calciumsulfat-Dihydrat, das als Gips seit übe Global and United States Sodium Triflate Market Insights, Forecast to 2027. Published on : 23 August 2021 | Pages: 121 | Report Code: 24CR-10432

(4-Methoxyphenyl)diphenylsulfonium triflate. IUPAC names 2 Other identifiers 1 . Print infocard. Substance identity Substance identity. The 'Substance identity' section is calculated from substance identification information from all ECHA databases. The substance identifiers displayed in the InfoCard are the best available substance name, EC number, CAS number and/or the molecular and. Abstract: Solid polymer electrolytes (SPEs) film containing methyl cellulose (MC) serves as polymer host and lithium triflate (LiCF 3 SO 3) as a doping salt are prepared by solution cast technique.The complexation between polymer and salt are confirmed by FTIR spectral analysis. The Li + observed to form a coordination bond with the oxygen atom of the ether group (C-OC) at wave number 1051 cm. Chemical Shift Table For certain compounds, the listed chemical shift pertains to the F shown in bold. The primary references for these values are: 1) the 1991 Bruker Almanac, and. 2) Compilation of reported F19 NMR chemical shifts, 1951 to mid-1967 by Claude H. Dungan and John R. Van Wazer. Negative shifts are those that appear upfield of. Crystal structure of scandium (III) triflate enneahydrated. European journal of solid state and inorganic chemistry. 1995, Vol 32, Num 11, pp 1089-1099 ; ref : 26 ref

triflate Übersetzung Englisch-Deutsc

Jia, H.; Häring, A. P.; Berger, F.; Zhang, L.; Ritter, T. Trifluoromethyl Thianthrenium Triflate: A Readily Available Trifluoromethylating Reagent with Formal CF 3. OUR STORY In 2015, Romeo and Isabella first met at her brother-in-law's birthday party. It was a quick exchange of words, and nothing else until a few months later, when they became Facebook friends. Immediately upon confirming Isabella's friend request, Romeo invited isabella to come downtown for a Cavs game, where he accidentally purchased 3 tickets to the game All lanes : Anti-TRIF antibody [OTI1G7] (ab139281) at 1/2000 dilution. Lane 1 : HEK-293T (human epithelial cell line from embryonic kidney transformed with large T antigen) cell lysate transfected with pCMV6-ENTRY control. Lane 2 : HEK-293T cell lysate transfected with pCMV6-ENTRY TRIF cDNA We report here that mouse macrophages undergo receptor-interacting kinase-3 (RIP3)-dependent but TNF-α-independent necrosis when Toll-like receptors (TLR) 3 and 4 are activated by poly(I:C) and LPS, respectively. An adaptor protein, Toll/IL-1 receptor domain-containing adapter inducing IFN-β (TRIF/TICAM-1), which is dispensable for TNF-α-induced necrosis, forms a complex with RIP3 upon.

Zinc triflate-mediated cyclopropanation of oxindoles with vinyl diphenyl sulfonium triflate: aTosylates And Mesylates – Master Organic ChemistryMolecules | Free Full-Text | Luminescent κ-Carrageenan-Based Electrolytes Containing Neodymium&quot;Halophilic Activation&quot; of Chlorosilanes: Allylation of Aldehydes Catalyzed by PlatinumMild and efficient method for the cleavage of benzylidene acetals by using erbium (III) triflatePresentation1