Presence Of Trifluoromethanesulfonic Acid Research Articles

A Triply Linked Copper(III) Dicarbacorrole Dimer.

A triply linked dicarbacorrole dimer (7) was synthesized from a new meso-meso singly linked dicarbacorrole dimer precursor (6) via an oxidative fusion reaction by 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) in the presence of trifluoromethanesulfonic acid (TfOH). Single crystal X-ray structure of 7 adopts a flat conformation with a length as ca. 15.946 Å and a width as 6.903 Å, which can be regarded as a short carbaporphyrinoid tape. Two coordinated Cu ions keeps the +3 oxidation state in 7, as confirmed by NMR spectroscopy, single crystal X-ray diffraction and X-ray photoelectron spectroscopy (XPS). This is in sharp contrast to the Osuka's triply linked tetrapyrrolic corrole dimers, where the inner 3NH form is not stable and thus can only act as a divalent ligand. Due to the non-aromatic nature of dicarbacorrole macrocycle, the largely decreased HOMO-LUMO gap and red-shifted absorption of 7 are best ascribed to the strong electronic interaction between two dipyrromethene-type chromophores. To our knowledge, this is the first fully fused carbaporphyrinoid dimer with β-β, meso-meso, β-β triply linkages prepared to date.

Urethane Synthesis in the Presence of Organic Acid Catalysts-A Computational Study.

A general mechanism for catalytic urethane formation in the presence of acid catalysts, dimethyl hydrogen phosphate (DMHP), methanesulfonic acid (MSA), and trifluoromethanesulfonic acid (TFMSA), has been studied using theoretical methods. The reaction of phenyl isocyanate (PhNCO) and butan-1-ol (BuOH) has been selected to describe the energetic and structural features of the catalyst-free urethane formation. The catalytic activities of DMHP, MSA, and TFMSA have been compared by adding them to the PhNCO-BuOH model system. The thermodynamic properties of the reactions were computed by using the G3MP2BHandHLYP composite method. It was revealed that in the presence of trifluoromethanesulfonic acid, the activation energy was the lowest within the studied set of catalysts. The achieved results indicate that acids can be successfully employed in urethane synthesis and the mechanism was described.

Unlock the C-N Bond Amidation of Enaminones: Metal-Free Synthesis of Enamides by Water-Assisted Transamidation.

The C-N bond transamidation of primary amides with N,N-dimethyl enaminones has been efficiently realized by heating in the presence of trifluoromethanesulfonic acid (TfOH). The method enables the practical synthesis of valuable enamides without the use of any metal reagent. In addition, this transamidation protocol can also be expanded to the reactions of sulfonamides, and the late-stage functionalization on sulfonamide drugs such as Celecoxib and Valdecoxib has been verified. Moreover, the participation of water in assisting the transamidation process has been identified by the isotope labeling experiments using D2O, disclosing a new possibility in designing catalytic tactic to other transamidation reactions.

Investigation of cationic transformations involving 5-ethynyl-4-arylpyrimidines

An innovative synthetic approach towards 5-ethynyl-4-arylpyrimidines was developed involving acid-catalyzed electrophilic alkylation of phenols with 5-bromopyrimidine, followed by oxidation and palladium-catalyzed Sonogashira cross-coupling reaction. Reactions of these compounds in the presence of trifluoromethanesulfonic acid were investigated. It was discovered these reactions take a different route for precursors with a different position of phenol group in an arene substituent.

Concise Synthesis of 1-Thioalkyl Glycoside Donors by Reaction of Per-O-acetylated Sugars with Sodium Alkanethiolates under Solvent-Free Conditions.

A relatively green method for synthesizing 1-thioalkyl glycosides has been developed, where sodium alkanethiolates were used to react with per-O-acetylated sugars instead of odorous alkyl mercaptans in the presence of BF3·Et2O without the use of solvents under mild conditions. Furthermore, we found that 1,2-trans-β-thioglycosides can be converted into corresponding 1,2-cis-α-thioglycosides in the presence of trifluoromethanesulfonic acid in nonpolar solvents under mild conditions. This provides a simple and efficient new approach for synthesizing challenging 1,2-cis-α-thioglycosides.

Fullerotetrahydroquinolines: TfOH/TsOH ⋅ H2O‐Mediated One‐Pot Two‐Step Synthesis and N‐Alkylation/Acylation/Carboamidation Reaction

AbstractA series of N‐unsubstituted/substituted fullerotetrahydroquinolines without a directly attached nitrogen atom were synthesized in moderate to good yields via a one‐pot two‐step reaction of [60]fullerene with arylamines and paraformaldehyde in the presence of trifluoromethanesulfonic acid and p‐toluenesulfonic acid monohydrate. Aromatic primary amines produce N‐unsubstituted fullereotetrahydroquinolines, while aromatic secondary amines give N‐substituted fullereotetrahydroquinoline derivatives. As precursors, N‐unsubstituted fullerotetrahydroquinolines could be further derivatized by the N‐alkylation/acylation/carboamidation reactions to produce a large variety of N‐substituted fullerotetrahydroquinolines containing Cl, NO2, C(O), and C(O)NH functional groups, which may have applications in the field of perovskite‐based solar cells. Plausible reaction pathways for the formation of N‐unsubstituted/substituted fullerotetrahydroquinolines were suggested to elucidate the above‐mentioned reaction process.magnified image

Preparation, Structure, and Reactivity of Pseudocyclic β‐Trifluorosulfonyloxy Vinylbenziodoxolone Derivatives

AbstractPseudocyclic β‐trifluorosulfonyloxy vinylbenziodoxolones were prepared starting from hydroxybenziodoxolones and alkynes in the presence of trifluoromethanesulfonic acid. The reaction of these compounds with azide anion leads to β‐azido vinylbenziodoxolones as products of vinylic nucleophilic substitution in which addition‐elimination reactions occur and the double bond configuration is retained. The structures of β‐trifluorosulfonyloxy vinylbenziodoxolone and β‐azido vinylbenziodoxolone were established by single crystal X‐ray diffraction.magnified image

Synthesis of Tetrahydroindolizino[8,7-b]indole Derivatives in the Presence of Fe(OTf)3 or CF3SO3H through Intramolecular Dearomatization of Indole.

We have developed a convenient synthesis of tetrahydroindolizino[8,7-b]indole derivatives via intramolecular dearomatization of indole. Highly functionalized tetrahydroindolizinoindoles can be prepared in the presence of trifluoromethanesulfonic acid in good to excellent yields (up to >99% yield) with novel designed pyrrole-tethered indoles. The same products can also be synthesized through a mild Fe(OTf)3-catalyzed process in acceptable to good yields (up to 75% yield).

Transformations of 1-phenethyl-1,2,3,6-tetrahydropyridines in the presence of trifluoromethanesulfonic acid

1-Phenethyl-1,2,3,6-tetrahydropyridines undergo intramolecular Friedel–Crafts reaction in trifluoromethanesulfonic acid medium, resulting in the formation of azatricyclic structures. It was shown that the direction of this reaction depended on the position of the substituent relative to the multiple bond in tetrahydropyridine. The structures of the obtained compounds were confirmed by a set of spectral analysis methods.

A Novel One-Pot Synthesis of N,N-Dimethylaminopyridines by Diazotization of Aminopyridines in Dimethylformamide in the Presence of Trifluoromethanesulfonic Acid

Diazotization of aminopyridines in the presence of trifluoromethanesulfonic acid gives the corresponding pyridinyl trifluoromethanesulfonates instead of expected diazonium salts. Pyridinyl trifluoromethanesulfonates can be converted to N,N-dimethylaminopyridines on heating in dimethylformamide via replacement of the trifluoromethanesulfonyloxy group. The reaction is accelerated under microwave irradiation. A novel one-pot procedure has been proposed for the synthesis of 2- and 4-(dimethylamino)pyridines from commercially available aminopyridines. The procedure provides high yields of the target products, and it can be regarded as an alternative to the known methods of synthesis of N,N-dimethylpyridin-4-amine (DMAP) widely used as base catalyst in organic synthesis.

High-glass-transition-temperature hydrocarbon polymers produced through anionic polymerization of 1,2/1,1-diphenyl-1,3-butadiene and subsequent cyclization

The anionic polymerization of 1,2-diphenyl-1,3-butaidiene and 1,1-diphenyl-1,3-butaidiene is conducted and a heat-resistant hydrocarbon polymer is obtained through subsequent cyclization of precursors. The controllability of polymerization depends on the type of solvent and temperature. When polymerization is conducted in a cyclohexane (CHX)/tetrahydrofuran (THF) solvent at room temperature, 1,2-diphenyl-1,3-butaidiene undergoes anionic polymerization with n-BuLi to quantitatively afford polymers of well-controlled molecular weights and narrow molecular weight distributions. In THF at room temperature, 1,1-diphenyl-1,3-butaidiene undergoes anionic polymerization to high monomer conversion (84 wt %). These Poly(diphenyl-butadiene) precursors are then cyclized in the presence of trifluoromethanesulfonic acid (CF3SO3H). The resulting cyclized product reached a high Tg value (approximately 170–233 °C) similar to that of cyclic hydrocarbon polymers such as polycyclohexane (Tg = 231 °C).

A new version of Umemoto’s reagents: A three-step one-pot preparation of 2,3,7,8-tetrafluoro-S-(trifluoromethyl)dibenzothiophenium triflate

A new one-pot method was developed for the practical preparation of powerful electrophilic trifluoromethylating agent, 2,3,7,8-tetrafluoro-S-(trifluoromethyl)dibenzothiophenium triflate 2. This method comprised of three steps; (1) in situ generation of trifluoromethanesulfinyl trifluoroacetate 7, (2) treatment of 3,3′,4,4′-tetrafluorobiphenyl with 7 in the presence of trifluoromethanesulfonic acid and trifluoroacetic anhydride, and (3) treatment of the resulting mixture with hydrogen peroxide. By means of this effective three-step one-pot method, 2 was prepared in a good isolated yield by simple water-washing method. It is thus expected that easy access to 2 may lead to its wider or new applications to many areas, because tetrafluoro reagent 2 is much more powerful than 2,8-difluoro-S-(trifluoromethyl)dibenzothiophenium triflate 1.

Enthalpy-Driven Polyisobutylene Depolymerization

Polyisobutylene (PIB) oligomers containing terminal alkene groups depolymerize rapidly at room temperature in the presence of trifluoromethanesulfonic acid and an arene solvent like benzene. This d...

TfOH-Promoted Transition-Metal-Free Cascade Trifluoroethylation/Cyclization of Organic Isothiocyanates by Phenyl(2,2,2-trifluoroethyl)iodonium Triflate.

An efficient and transition-metal-free method for the synthesis of the structurally diversified trifluoroethylthiol phenanthridines and 3,4-dihydroisoquinolines is described. Various 2-isothiocyanobiaryls and aryl alkyl isothiocyanates reacted with phenyl(2,2,2-trifluoroethyl)iodonium triflate in CH2Cl2 in the presence of trifluoromethanesulfonic acid at 40 °C to form the corresponding trifluoroethylation/cyclization products in good to quantitative yields. This work represents the first construction of trifluoroethylthiol phenanthridine and isoquinoline derivatives from isothiocyanates in the absence of transition-metal catalysts by a one-pot procedure.

Synthesis of Five-Membered Iodine-Nitrogen Heterocycles from Benzimidazole-Based Iodonium Salts.

Pseudocyclic 2-benzimidazolyl-substituted diaryliodonium salts were obtained by the reaction of the corresponding [hydroxy(tosyloxy)iodo]arenes with arenes in the presence of trifluoromethanesulfonic acid. X-ray structural analysis of these iodonium salts confirmed their pseudocyclic structure with a short (2.57-2.58 Å) noncovalent I···N interaction. Treatment of 2-benzimidazolyl-substituted diaryliodonium triflates with a base afforded novel five-membered iodine-nitrogen heterocycles.

Synthesis, Structure, and Synthetic Potential of Arenediazonium Trifluoromethanesulfonates as Stable and Safe Diazonium Salts

Aromatic diazonium salts are valuable building blocks for organic synthesis; however, in most cases, they are unstable, unsafe, poorly soluble, and/or expensive. In this paper, we have shown that a variety of stable and safe arenediazonium triflates ArN2+ TfO– can be obtained easily and in high yields by diazotization of anilines with tert‐butyl nitrite in the presence of trifluoromethanesulfonic acid. Arenediazonium triflates are relatively shelf‐stable in the dry state. They dissolve well in water, as well as polar and even nonpolar organic solvents. Less than 800 J/g of energy is released during the thermal decomposition of these salts, which indicates their explosion safety. Arenediazonium triflates have a high reactivity in the known reactions of diazonium chemistry, and undergo an unusual metal‐free chlorodediazonization reaction with chloroform and CCl4.

Dodecabromo- and Dodecaiodocentrohexaindane: Td -Symmetrical Key Building Blocks for Twelve-Fold Cross-Coupling Reactions and Six-Fold Orthogonal Extension.

Centrohexaindane was converted into its Td -symmetrical 2,3,6,7,10,11,14,15,20,21,26,27-dodecabromo and -dodecaiodo derivatives using N-bromo- and N-iodosuccinimide, respectively, in the presence of trifluoromethanesulfonic acid as a catalyst in single, highly efficient steps. Sonication or microwave irradiation was indispensable to enforce exhaustive halogenation of the twelve equivalent peripheral positions of this Cartesian polyaromatic hydrocarbon. Despite their extremely poor solubility in most organic solvents, the new dodecahalo derivatives were fully characterized, including single crystal X-ray structure analysis. Subsequent Pd0 -catalyzed twelve-fold C-C cross-coupling reactions furnished the corresponding dodecamethyl, dodeca(phenylethynyl) and dodecaphenyl derivatives in good to excellent yields. The latter hydrocarbon was also analyzed by X-ray diffraction.

Energy-Efficient Hydrogen Evolution by Fe-S Electrocatalysts: Mechanistic Investigations.

The intrinsic catalytic property of a Fe-S complex toward H2 evolution was investigated in a wide range of acids. The title complex exhibited catalytic events at -1.16 and -1.57 V (vs Fc+/Fc) in the presence of trifluoromethanesulfonic acid (HOTf) and trifluoroacetic acid (TFA), respectively. The processes corresponded to the single reduction of the Fe-hydride-S-proton and Fe-hydride species, respectively. When anilinium acid was used, the catalysis occurred at -1.16 V, identical with the working potential of the HOTf catalysis, although the employment of anilinium acid was only capable of achieving the Fe-hydride state on the basis of the spectral and calculated results. The thermodynamics and kinetics of individual steps of the catalysis were analyzed by density functional theory (DFT) calculations and electroanalytical simulations. The stepwise CCE or CE (C, chemical; E, electrochemical) mechanism was operative from the HOTf or TFA source, respectively. In contrast, the involvement of anilinium acid most likely initiated a proton-coupled electron transfer (PCET) pathway that avoided the disfavored intermediate after the initial protonation. Via the PCET pathway, the heterogeneous electron transfer rate was increased and the overpotential was decreased by 0.4 V in comparison with the stepwise pathways. The results showed that the PCET-involved catalysis exhibited substantial kinetic and thermodynamic advantages in comparison to the stepwise pathway; thus, an efficient catalytic system for proton reduction was established.

Triazine-Based Cationic Leaving Group: Synergistic Driving Forces for Rapid Formation of Carbocation Species.

A new triazine-based cationic leaving group has been developed for the acid-catalyzed alkylation of O- and C-nucleophiles. There are two synergistic driving forces, namely, stable C═O bond formation and charge-charge repulsive effects, involved in the rapid generation of the carbocation species in the presence of trifluoromethanesulfonic acid (∼200 mol %). Considerable rate acceleration of benzylation, allylation, and p-nitrobenzylation was observed as compared to the reactions with less than 100 mol % of the acid catalyst. The triazine-based leaving group showed superior p-nitrobenzylation yield and stability in comparison to common leaving groups, trichloroacetimidate and bromide. A plausible reaction mechanism (the cationic leaving group pathway) was proposed on the basis of mechanistic and kinetic studies, NMR experiments, and calculations.

A versatile ternary ion pair complex of 2′-amino-1,1′-binaphthalen-2-ol for sensing enantiomers and assignment of absolute configuration

2′-Amino-1,1′-binaphthalen-2-ol (NOBIN) serves as a versatile chiral solvating agent (CSA) in the presence of trifluoromethanesulfonic acid (TFMS). The formation of a ternary complex has been established by NMR, UV–Vis, fluorescence and IR studies. The mechanism of interactions among the three components in the ternary complex has been proposed and the ternary complex structures of different diastereomers have been established by DFT based theoretical calculations. The present protocol has its ubiquity not only in the analysis of the enantiomeric composition of molecules possessing diverse functionalities, but also in determining the stereospecific assignment of hydroxy acids.