Ethyl Triflate Research Articles

A fluorescent probe for alkylating agents and its quantification of triflate as a genotoxic impurity.

The responses of a reaction-based fluorescent probe BI-Py towards alkyl halide, epoxide, carbonate, sulfate, sulphonate and triflate were evaluated and the probe achieved selective detection of ethyl triflate in acetonitrile with a LOD of 1.08 μM. BI-Py exhibited great potential for detecting triflate as a genotoxic impurity in drug substances.

Triflate esters as in-situ generated initiating system for carbocationic polymerization of vinyl ethers, isoprene, myrcene and ocimene

Thermo-induced carbocationic polymerization of isobutyl vinyl ether (IBVE), isoprene, myrcene and ocimene is reported using triflate esters as in-situ generated single-molecule initiating system. 3-Methyl-2-butenyl triflate is used for IBVE polymerization at room temperature resulting in polymers with Mn∼9500gmol−1 and Mw/Mn∼2. Triflate-ester initiated polymerization of isoprene leads to oligomers with branched and ultimately cross-linked structures. Myrcene cationic polymerization, in CH2Cl2 or cyclohexane, using 2-propenyl triflate and 1-(4-metoxyphenyl)ethyl triflate as initiators yields low molar mass oligomyrcenes with loss of olefinic protons. Ocimene cationic polymerization is reported for the first time.

Conversion of Dinitrogen into Acetonitrile under Ambient Conditions.

About 20% of the ammonia production is used as the chemical feedstock for nitrogen-containing chemicals. However, while synthetic nitrogen fixation at ambient conditions has had some groundbreaking contributions in recent years, progress for the direct conversion of N2 into organic products remains limited and catalytic reactions are unknown. Herein, the rhenium-mediated synthesis of acetonitrile using dinitrogen and ethyl triflate is presented. A synthetic cycle in three reaction steps with high individual isolated yields and recovery of the rhenium pincer starting complex is shown. The cycle comprises alkylation of a nitride that arises from N2 splitting and subsequent imido ligand centered oxidation to nitrile via a 1-azavinylidene (ketimido) intermediate. Different synthetic strategies for intra- and intermolecular imido ligand oxidation and associated metal reduction were evaluated that rely on simple proton, electron, and hydrogen-atom transfer steps.

Conversion of Dinitrogen into Acetonitrile under Ambient Conditions

AbstractAbout 20 % of the ammonia production is used as the chemical feedstock for nitrogen‐containing chemicals. However, while synthetic nitrogen fixation at ambient conditions has had some groundbreaking contributions in recent years, progress for the direct conversion of N2 into organic products remains limited and catalytic reactions are unknown. Herein, the rhenium‐mediated synthesis of acetonitrile using dinitrogen and ethyl triflate is presented. A synthetic cycle in three reaction steps with high individual isolated yields and recovery of the rhenium pincer starting complex is shown. The cycle comprises alkylation of a nitride that arises from N2 splitting and subsequent imido ligand centered oxidation to nitrile via a 1‐azavinylidene (ketimido) intermediate. Different synthetic strategies for intra‐ and intermolecular imido ligand oxidation and associated metal reduction were evaluated that rely on simple proton, electron, and hydrogen‐atom transfer steps.

Synthesis and reactivity of bis(diphenylphosphino)amine-bridged heterobimetallic iron–platinum μ-isonitrile and μ-aminocarbyne complexes

Reaction of [(OC)3Fe(μ-CO)(μ-dppa)Pt(PPh3)] (1) (dppa = bis(diphenylphosphino)amine) with various isonitriles in a 1:1 or 1:2 ratio yields the isonitrile-bridged compounds [(OC)3Fe(μ-CN-R)(μ-dppa)Pt(PPh3)] (2) and [(OC)2(RNC)Fe(μ-CN-R)(μ-dppa)Pt(PPh3)] (3), respectively. However, addition of tert-butylisonitrile to 1 affords the carbonyl-bridged complex [(OC)2(tert-BuNC)Fe(μ-CO)(μ-dppa)Pt(PPh3)] (2g). Upon treatment of [(OC)3Fe(μ-CN-o-anisyl)(μ-dppa)Pt(PPh3)] (2b) with SO2, the μ-CNR ligand is chased from its bridging position to give the sulfur dioxide-bridged compound [(OC)2(o-anisylNC)Fe(μ-SO2)(μ-dppa)Pt(PPh3)] (4). These compounds are converted to the μ-aminocarbyne salts [(OC)2(L)Fe{μ-CN(R)R’}(μ-dppa)Pt(PPh3)]+ (5 R’ = Me, Et) by N-alkylation using [Me3O][BF4] or ethyl triflate as electrophiles. In function of the sterical crowding exerted by μ-aminocarbyne groups, two stereoisomers can be formed. Upon addition of P(OMe)3 or tert-BuNC to 5, no carbonyl substitution occurs. Instead the Pt-bound PPh3 ligand is replaced by L′ in a regioselective manner to give [(OC)2(L)Fe{μ-CN(Me)R}(μ-dppa)Pt(L′)][BF4] (5e, 5f, 5g). Deprotonation of the N–H function of the bis(diphenylphosphino)amine ligand of salts 5 by KSi(OMe)3 or KH produces the zwitterionic compounds [(OC)2(L)Fe{μ-CN(R)R’}(μ-Ph2PNPPh2)Pt(PPh3)] (6). The latter react with various organic and inorganic electrophiles to produce the N-alkylated or metallated aminocarbyne complexes [(OC)2(L)Fe{μ-CN(R)R’}{μ-Ph2PN(E)PPh2}Pt(PPh3)]+ (7: E = Me, 8: E = AuPPh3, CuAsPh3, CuPPh3, HgMe). The molecular structures of 2c, 3b, 5b, 8a and 8b have been determined by X-ray diffraction studies.

A Convenient Synthesis of Triflate Anion Ionic Liquids and Their Properties

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 triflate by this invented process. The properties of ionic liquids containing the triflate anion are determined and discussed.

Reactivity of (R)-4-Phenyloxazolidin-2-thione Chiral Auxiliary: From Deprotection to Heterocyclic Interconversion

Using (R)-3-beilzyl-4-phenyloxazolidin-2-thione (2) as model compound, a sequence of reactions has been established that allows the chiral auxiliary deprotection to furnish a primary amine. Treatment of 2 with ethyl triflate (3b) followed by ring opening with RbI (4b) and HI elimination with DBU, in a one pot process, gave S-ethyl-N-benzyl-N-1-phenylvinylcarbamothioate (5, 95% yield) which acid hydrolysis (9) and saponification liberated benzylamine. Through a mechanistic study, we showed that the activated chiral oxazolidin-2-thione 3b is a tunable intermediate towards the corresponding oxazolidin-2-one 7, thiazolidin-2-one 8 and thiazolidin-2-thione 10. All those reactions were chemoselective and preserved the chiral center. A structural analysis of this series of heterocycles, by NMR and X-ray diffraction, has been performed.

Metal triflates combined with caffeine based imidazolium salts: A new family of highly efficient and reusable catalysts

Abstract The direct alkylation of caffeine ( 1 ), by ethyl triflate gave 1,3,7-trimethyl-9-ethylxanthinium triflate ( 2 ) which led to 1,3,7-trimethyl-9-ethylxanthinium bis(trifluoromethanesulfonyl)amide ( 3 ) after methathesis with LiNTf 2 ; 3 proved to be an ionic solid which can be used for the recovery of metal triflates (M(OTf) n with M = Sc, La, Yb, Cu, Hf, Bi). These reusable catalysts proved to be efficient Lewis acids for Diels–Alder reactions leading to very little or no polymerisation of the diene. In the case of bismuth (III) triflate, the catalyst can be recovered and reused at least 10 times without loss of activity.

Nucleophilic character of a charge neutral, high oxidation state d0 zirconium trimethylenemethane complex.

The nucleophilic character of a charge neutral, high oxidation d0 zirconium trimethylenemethane (TMM) class of compound of general structure Cp*Zr(TMM)[N(R1)C(Me)N(R2)], 1a (R1 = R2 = i-Pr) and 1b (R1 = t-Bu, R2 = Et), is presented through documentation of its reactivity with a range of alkyl and silyl halides and triflates, including unactivated ones such as ethyl triflate. These results should contribute to efforts directed toward expanding the synthetic chemist's toolbox of synthetic methods for the construction of complex organic molecules.

Synthesis of Polyfluorinated Alkynes, Novel Building Blocks for Fluorous Chemistry

Ethynyldimethylphenylsilane (2) was lithiated with butyllithium and reacted with (perfluorohexyl)ethyl triflate (1) to afford silylated 4-(perfluorohexyl)butyne 3, which was deprotected with potassium fluoride to give 4-(perfluorohexyl)butyne 4. Lithiation of fluoroalkyne 4 with butyllithium followed by the addition of polyfluoroalkyl triflate 1 furnished bis(perfluorohexyl)butyne 5 in a moderate yield. Polyfluoroalkylated alkynes 3, 4 and 5 are perspective building blocks for fluorous chemistry, the sufficient nucleophilic properties of which are preserved by one or two ethylene spacers between the triple bond and perfluoroalkyl group(s).

2-(Perfluoroalkyl)ethyl Triflates, Building Blocks for the Synthesis of Bis(polyfluoroalkylated) Cyclopentadienes

Fluorinated building blocks, 2-(perfluorohexyl)ethyl triflate (11 a) and 2-(perfluorooctyl)ethyl triflate (11 b) were prepared from the corresponding fluoroalkanols and triflic anhydride. Fluorinated triflates 11 were employed for the preparation of bis(polyfluoroalkylated) cyclopentadienes 9, which are potential ligands for homogeneous catalysts used in fluorous biphase systems. Fluorotriflates 11 are also excellent substrates for the preparation of various polyfluorinated compounds, e.g. nitriles or azides, by nucleophilic substitution.

Electrophilic chemistry of the cubic arsaalkyne tetramer (AsCtBu)4: Arsonium ions of ethylation (EtOTf), benzylation (PhCH2OTf), and mono‐ and diprotonation (FSO3H/SO2)

AbstractThe cubic arsaalkyne tetramer 2 reacts at room temperature with ethyl triflate to give the As‐ethylated arsonium salt 4. A similar reaction of 2 with benzyl triflate (generated in situ via PhCH2Cl/AgOTf) gives the As‐benzylated salt 5. Low‐temperature protonation of 2 with FSO3H/SO2 produces a mixture of arsonium ions 6 and 7 resulting from mono‐ and diprotonation. The NMR characteristics of the resulting arsonium ions are discussed and compared with those of the corresponding phosphonium ions derived from the tetraphosphacubane 3. The FAB mass spectrum of 4 and its decomposition products (FAB‐CAD‐MS/MS) are also discussed.

Kinetics and mechanism of the alcoholyses of ethyl fluorosulphate

AbstractThe alcoholyses of ethyl fluorosulphate in methyl, ethyl, n‐propyl, isopropyl, n‐butyl, isobutyl, tert‐butyl and n‐pentyl alcohols in the initial concentrations and temperature ranges of (1–10) 10−3 M and − 15.00 to 22.00 °C, respectively, were studied. The reactions follow pseudo‐first‐order kinetic laws up to at least ca 75 per cent ester conversions. At 10°C the experimental rate constant for ethanolysis is similar to that of ethyl triflate but much smaller than for its hydrolysis. The reactivity of the ester is ca 104–105 times higher than that of alkyl halides and benzenesulphonates. In alcohol–benzene and alcohol–acetone mixtures the ΔH≠ and ΔS≠ activation parameters are only slightly affected by the media composition. The effect of the ‘lyate ion’ on the kinetics of these reactions were investigated and the effects of changes in the dielectric constant of the media were evaluated. It is concluded that the alcoholyses of the ester fulfil the requirements for predominant SN2‐type mechanism, where the reaction ground states are more polar than the corresponding transition states.

Nucleophilic attack on cluster-bound acetylide ligands derived from the iron ketenylidene, [Fe3(CO)9(CCO)]2?

Reaction of the iron ketenylidene (PPN)2[Fe3(CO)9CCO] [PPN =bis (triphenylphosphine)nitrogen(+1)] with trifluoroacetic anhydride forms a highly electrophilic acetylide cluster (PPN)[Fe3(CO)9CCOC(O)CF3] (lc), analogous to the known compounds (PPN)[Fe3(CO)9CCOR] [R=Et, (Ia); Ac, (Ib)] prepared from the reaction of ethyl triflate and acetyl chloride on the ketenylidene. Reaction of phosphines and (Ib, c) yield phosphonium acetylides [Fe3(CO)9CCPR3] [(II),R=Ph], with loss of (PPN)[CH3CO2] or (PPN)[CF3CO2]. Additionally, (Ic) and triphenylarsine react to give an analogous arsonium acetylide [Fe3(CO)9CCAsPh3] (III). No reaction occurs when an excess of arsine is added to (Ib). The reaction of (Ib, c) with anionic nucleophiles is reported, including reaction of Na[CpFe(CO)2] and (Ib) to afford an unusual metallated acetylide cluster (PPN) [Fe3(CO)9CCFe(CO)2Cp] (IV). Clusters (II), (III), and (IV) are spectroscopically characterized and a single crystal x-ray structure determination of (IV) is reported. (PPN)[Fe3(CO)9CCFe(CO)2Cp] (IV) crystallizes in the monoclinic space group P21/n;a=17.793(2) A;b=16.108(3) A;c=18.157(3) A;β=107.62(1)0;V=4959(3) A3;Z=4. Refinement of 469 variables on 5981 observed [I>3σ(I)] reflections converged toR=3.5% andRw=4.7%.

A novel synthesis of 4-alkyl-4-(4-methoxyphenyl)cyclohex-2-en-1-ones and the Sceletium alkaloid, o-methyljoubertiamine.

The dianion formed by reduction of (η 6:η 6-4,4′-dimethoxybiphenyl)[Cr(CO) 3] 2 reacts with electrophiles such as methyl or ethyl triflate or allyl tosylate at −78 °C followed by CF 3CO 2H and I 2 to form 4-alkyl-4-(4-methoxyphenyl)cyclohex-2-en-1-ones.

Trifluoromethanesulphonic acid as a catalyst for the ethylation of benzene

At room temperature and a pressure of ethene of 1 atm, anhydrous trifluoromethanesulphonic (triflic) acid is a more effective catalyst for the ethylation of benzene than AlCl3, FSO3H, and anhydrous H2SO4. It has an activity comparable to that found for a 1 : 1 mixture of FSO3H–SbF5, and under the most favourable conditions the yield of ethylbenzene is ca. 38% based on the amount of benzene reacted. Although the initial rate of ethylation is rapid, the reaction effectively ceases after 30–60 min depending on the reaction conditions. The reason for this has mainly been shown to be strong complexation of the triflic acid to polyethylbenzene derivatives in the catalyst layer, but also, in part, to the competing formation of ethyl triflate, which is inactive as an ethylating agent under the conditions used.

Cationic polymerization of 1‐azabicyclo[4.2.0]octane, 1 alkylation

AbstractThe rate constants of the reaction of 1‐azabicyclo[4.2.0]octane (1) with different alkyl esters or halides were measured using 1H NMR and UV spectroscopy as well as conductometric methods. The reactivities of the alkylating agents were found to decrease with increasing nucleophilicity of the derived anions (CF3SO⊖3 > I⊖ > Br⊖ > picryl⊖ > Cl⊖). Reactivities of all ethyl derivatives, except ethyl chloride, are higher than the reactivity of the 1‐alkyl‐1‐azoniabicyclo[4.2.0]octane cation (2), which means that for these compounds the rate constant of initiation is higher than that of propagation. The reactions proceed much slower in methanol than in nitrobenzene due to the strong donor‐acceptor interactions between methanol and 1. Attempts to observe covalent active centers directly by NMR spectroscopy in the polymerization mixture or to detect them kinetically, were unsuccessfull. The reactivity of ethyl triflate, modelling the hypothetical active center, was found to be 2.104 times higher than the reactivity of ions 2. This is ascribed to the high strength of the bond in the cation 2, not sufficiently compensated by the strain of the four‐membered ring.

Alkyltrifluoromethanesulphonates as alkylating reagents for aromatic compounds

Download options Please wait... Article information DOI https://doi.org/10.1039/P19800002887 Article type Paper Download Citation J. Chem. Soc., Perkin Trans. 1, 1980, 2887-2893 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Alkyltrifluoromethanesulphonates as alkylating reagents for aromatic compounds B. L. Booth, R. N. Haszeldine and K. Laali, J. Chem. Soc., Perkin Trans. 1, 1980, 2887 DOI: 10.1039/P19800002887 To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Search articles by author Brian L. Booth Robert N. Haszeldine Khosrow Laali

Synthesis of some novel trifluoromethanesulfonates and their reactions with alcohols

Allyl triflate, propargyl triflate, pentyl triflate, 2-(2-fluoro-2,2-dinitroethoxy)ethyl triflate, 2-fluoro-2,2-dinitroethyl triflate, and 1,2,3-propanetritriflate were prepared from the alcohols using triflic anhydride and pyridine. 1,4-Butaneditriflate was formed from tetrahydrofuran and triflic anhydride. In the presence of potassium carbonate, pentyl triflate, allyl triflate, propargyl triflate, 1,4-butaneditriflate, and 2-( 2-fluoro-2-2-dinitroethyoxy)ethyl triflate reacted in chlorinated hydrocarbon solvents at ambient temperature with 2-fluoro-2,2dinitroethanol to give the corresponding ethers, without skeletal rearrangement. l12,3-Propanetritriflate underwent monosubstitution and elimination to yield 3-( 2-fluoro-2,2-dinitroethoxy)-2-propenyl triflate. Pentyl triflate and 2,2,2-trifluoroethanol gave pentyl 2,2,2-trifluoroethyl ether. When sodium sulfate was used instead of potassium carbonate to scavenge liberated triflic acid, pentyl triflate and 2,2-dinitropropanol gave a mixture of the 1-, 2-, and 3-pentyl ethers. Under these conditions, 2-fluoro-2,2-dinitroethanol, 2,2-dinitropropanol, and 2,2,2-trinitroethanol, as well as pentanol, reacted with isopropyl triflate to give the corresponding isopropyl ethers. Allyl triflate was allowed to react similarly with 2,2-dinitropropanol, 2,2,2-trinitroethanol, and 2,2-dinitro-1,3propanediol to give the allyl ethers. The high reactivity of the trifluoromethanesulfonate (triflate) group in solvolysis and displacement reactions has been the subject of a number of recent investigations. Thus, methyl and ethyl triflates were reported to undergo solvolysis more than lo4 times as fast as the corresponding tosylate~.~~~ The use of the triflate leaving group in otherwise unreactive polycyclic systems has extended the range of solvolysis reaction^,^-^ and vinyl triflates have been used extensively in studies of vinyl ~ations.~-~O Xo attempts have been reported, however, to prepare a triflate ester more reactive than the ethyl derivative. Such extremely reactive alkylating agents would be expected to extend the range of weakly nucleophilic reagents that can be alkylated. The triflates prepared in this work are shown in Table I. Most of these compounds were synthesized from the corresponding alcohols by the commonly used4 triflic anhydride-pyridine method. Methylene chloride and carbon tetrachloride were used as solvents. Methyl triflate, because of its low boiling point, was prepared conveniently, from dimethyl sulfate by a procedure previously used for the corresponding fluorosulfonate.'l The reaction of tetrahydrofuran with triflic anhydride gave 1,4-butaneditriflate1 a reaction similar to ring openings with mixed sulfonic-carboxylic anhydrides. l2 This ditriflate and l12,3-propanetriflate, prepared from glycerol, are the first reported polyfunctional examples. Allyl triflate, propargyl triflate, and isopropyl triflate were not sufficiently stable for elemental analysis and were characterized by spectral data, described in