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Propargyl α-aryl-α-diazoacetate a new class of reagent is developed for the effective C H bond functionalization of 1,3-diketones at room temperature. The combination of scandium triflate and propargyl α-aryl-α-diazoacetate proved to be efficient catalyst-reagent system for the controlled C H bond functionalization to afford 1,3-dicarbonyl alkylation. The protocol uses inexpensive Sc(OTf)3 (5 mol%) and the reaction did not require the use of expensive catalysts or ligands and worked efficiently at room temperature. The practicality of the protocol has been demonstrated by the gram scale synthesis.

A three-component coupling procedure was developed to construct the entire prostaglandin (PG) skeleton under HMPA-free and stoichiometric conditions via a combination of dimethylzinc-aided conjugate addition of an ω-side-chain vinyllithium with (R)-4-hydroxy-2-cyclopentenone and the direct trapping of the resulting enolate with an α-side-chain propargyl triflate. Dimethylzinc effectively regulated both the conjugate addition and alkynylation reactions. Thus, the method afforded protected 5,6-didehydro-PGE2, a common intermediate for the general synthesis of natural PGs and the stable artificial prostacyclin (PGI2) analog isocarbacyclin in 88% yield. The utility of the method was further applied to the syntheses of novel intermediates, which are useful for the straightforward synthesis of 15R-TIC and 15-deoxy-TIC in 79% and 86% yield, respectively.

Hydrazides and amines were N-formylated by DMF in the presence of tert-butyldimethylsilyl triflate (TBSOTf) at room temperature, in good to excellent yields.

Glycosylation reactions are significant as they provide access to model compounds that are useful for elucidating biochemical pathways. Herein, we describe the development of glycosyl ortho-alkynylbenzoates as novel, bench-top stable, and readily available glycosyl donors. Glycosylation is promoted by inexpensive trimethylsilyl triflate (TMSOTf) in combination with N-iodosuccinimide (NIS) under mild reaction conditions; hence, the novel glycosyl donors are promising reagents for the synthesis of glycosides.

A novel and highly efficient method for activating highly hindered acid anhydrides towards the acylation of alcohols and carbohydrate-derived polyols has been developed. This new method relies on the capacity of the hafnium triflate catalyst Hf(OTf)2 to activate highly hindered acid anhydrides, and to direct the acylation reaction. This new acylation protocol is mild and proceed at room temperature with low catalyst loading. The method is versatile and has been extended to different alcohol substrates with different steric encumbrance as well as carbohydrate-derived polyols to afford the corresponding ester products in good to excellent yields.

An unexpected reaction between benzynes and isocyanates to generate aromatic amines has been developed under transition-metal-free conditions. The in situ prepared anions formed through cleavage of the N C bond in isocyanates, reacted with aryne precursors to afford various aniline derivatives in moderate to excellent yield and tolerated various substituents on the o-silyl aryl triflate and the isocyanate.

Using indium (III) triflate as a mild Lewis acid catalyst, the Friedel Crafts alkylation of o-hydroxy bisbenzylic alcohols with aromatic/heteroaromatic arenes under solvent free conditions was achieved to give the corresponding unsymmetrical triarylmethanes in high yields (up to 80% yield). Calculation of the different green metrics for the above reaction revealed it to have high atom economy (94–96%), high reaction mass efficiency (66–77%) and high carbon efficiency (70–80%). The Lewis acid was found to be air and moisture tolerant. The protocol was found to be operationally simple and can be carried out in an “open-flask” leaving behind water as the sole by product. Gratifyingly the Lewis acid catalyst could be recycled and reused up to 5 catalytic cycles without compromising much on the yield thus further highlighting the importance of the protocol.

The mechanism of Pd(OAc)2-catalyzed trifluoroethylation of aromatic systems is explored using the density function theory (DFT) computations. The calculation results indicate that the whole catalytic cycle involves a coordinated process of catalyst Pd(OAc)2 with acetanilide 1a, a C–H bond activation and a two-step migration of CF3CH2– group. The interesting role of additive (CF3COOH) is that it can react with substrate 2a (mesityl(trifluoroethyl)iodonium triflate) to form an active species mesityl(trifluoroethyl)iodonium trifluoroacetate 2a′. 2a′ can assist the C–H activation to decrease the rate-limiting free energy barrier of the catalytic reaction by changing the rate-limiting step from the transferring process of CF3CH2– group to the C–H bond activation.

A new method was developed for the synthesis of fully substituted 3-haloisoxazoles. This process includes the synthesis of isoxazoline N-oxides from α-halonitroalkenes and subsequent dehydration mediated by the silyl triflate/triethylamine system.

A catalyst- and additive-free ring-opening polymerization of tetrahydrofuran initiated by phenyl(trifluoroethyl)iodonium triflate ([PhICH2CF3][OTf]) without using photo-irradiation is developed. The reaction proceeded at room temperature or elevated temperature to form CF3CH2-terminated polytetrahydrofuran in good yields and with different Mn(NMR) values. Phenyl(trifluoroethyl)iodonium triflate was evidenced as a much powerful mediator for cationic ring-opening polymerization of THF in comparison with other commonly used initiators. The temperature, concentration of [PhICH2CF3][OTf], and reaction time had a significant influence on both yield and number-average molecular weight of the polymerized product. This reaction provided an interesting synthetic route to novel polytetrahydrofuran bearing a trifluoroethyl end group.

Regioselective elimination of a vicinal bis-triflate having an adjacent ether oxygen functional group has been developed. Considered in the context of our studies of the regioselective elimination of vicinal dibromide, the key to the mechanism involves the electron-withdrawing inductive effect of the neighboring oxygen functional group. Aliphatic vinyl triflate was shown to be effective in Suzuki–Miyaura cross coupling compared with corresponding aliphatic vinyl bromide.

The heterocyclization of gem-dichlorocyclopropanes upon treatment with nitronium triflate in organic nitriles was studied and the influence of the medium on the reaction pathway was shown. While in anhydrous solvent 5-chloroisoxazole was the only product, the admixture with water promoted a three-component heterocyclization affording 4-chloropyrimidine N-oxides. This phenomenon was rationalized using DFT calculations.

An air-stable hypervalent organoantimony (III) triflate complex (PhN(CH2C6H4)2SbOSO2CF3) having intramolecular N → Sb coordination was synthesized and characterized by techniques such as 1H NMR, 13C NMR, TG-DSC, X-ray diffraction and elemental analysis. The complex shows relatively strong Lewis acidity (0.8

Stereoselective β-mannosylation has been investigated via cesium carbonate-mediated anomeric O-alkylation of d -mannose-derived lactol with various electrophiles. It was found that electrophiles bearing trifluoromethanesulfonate (triflate) as the leaving group are most reactive. In addition, a highly efficient formal synthesis of potent calcium signal modulator acremomannolipin A has been achieved using this β-mannosylation method.

An efficient and simple route for the synthesis of ortho-hydroxyaryl ketones has been developed. The microwave-assisted direct C-benzoylation of phenols and naphthols in the presence of metal triflates afforded the corresponding ortho-hydroxyaryl ketones in moderate to excellent yields. Bismuth triflate showed the best catalytic performance compared to other metal triflates. The protocol has advantages including short reaction times, high chemoselectivity towards C-acylation, and simple work-up. Additionally, bismuth triflate can be easily recovered and reused several times without significant loss of catalytic performance.

Zinc(II) triflate catalyzed three-component coupling reactions of alkynes, amines and aldehydes leading to the formation of aryl/alkyl substituted quinolines has been described. Notably, the reaction proceeded efficiently and effectively without the use of ligand, co-catalyst, solvent or inert atmosphere. This robust solvent-free process operates under an ambient atmosphere and avoids the use of precious metals, hazardous solvents and harsh reaction conditions. This atom economic process eliminates the waste generated in the multistep synthesis. Additionally, a pseudo three-component Povarov reaction of amines and butanal proceeds under the same green conditions enabling the formation of 2,3-dialkyl quinolines.

In this work, the biofuel target compound 2-ethyl-5,5-dimethylcyclopenta-1,3-diene (1) and its exo isomers (9a and 9b), were successfully synthesized via two different pathways from the common intermediate 4,4-dimethylcyclopent-2-ene-1-one (2). The first pathway produced the endocyclic product as a pure isomer via a triflate intermediate obtained from ketone 2 in 60% yield, followed by copper-catalyzed coupling with ethyl magnesium bromide in 63% yield. The second pathway employed a Grignard reaction with ketone 2, which generated an alcohol that was immediately subjected to mild acid-catalyzed elimination to yield primarily a mixture of exo isomers 9a and 9b in 46% yield. The preparation method developed by this work allowed for the production of a sufficient quantity of these targets to evaluate their fuel properties, which will be reported in a separate study.

A convenient method was developed for the cyclopropanation of aryl acetates and aryl acetonitrile using vinyl diphenyl sulfonium triflate salt. The newly developed conditions are simple, mild, and compatible with a wide range of functional groups, without the need to apply an inert atmosphere, or alkali bases.

An efficient and straightforward method for the synthesis of 2-benzyl-3-arylquinoline derivatives is reported involving the domino reaction of substituted arylamines and styrene oxides in the presence of 10 mol% ytterbium(III) triflate in acetonitrile at 80 °C. Additionally, the reaction of aliphatic epoxides with p-anisidine provided 2,3-dialkylquinoline derivatives under identical reaction conditions. Important features of the protocol are ease of handling, broad substrate scope, good yields, and the formation of two C N and two C C bonds.

3,5-Dibromopridinium trifluoromethanesulfonate catalyzes the intramolecular alkyne-carbonyl metathesis reaction of a variety of O-propargylated 2-hydroxyarylaldehydes and ketones bearing alkyl, aryl and heteroaryl substituted internal alkynes to provide various 3-(hetero)aroyl 2H-chromenes in high yields.

An efficient tandem reaction approach is described to prepare 4-chromanones from electron-rich phenols and 3,3-dimethylacrylic acid or trans -crotonic acid in boiling toluene using 20 mol % bismuth(III) triflate as the catalyst. The reaction is also successful from the corresponding aryl esters of each of these acids under the same conditions. The procedure is convenient to perform, and 25–90% yields of products are realized following chromatography. A range of substrates is included (14 substrates for each acid) to help define the scope of the process. Additional experiments are reported, which confirm that the sequence of events involves (1) esterification, (2) Fries rearrangement and (3) oxa-Michael ring closure.

An eco-friendly and readily accessible 2,2,6,6-tetramethylpiperidinium triflate was found as highly-selective and self-separated catalyst for esterification under solvent-free condition. The X-ray crystallography revealed that it formed a ‘hydrophobic wall’ which could effectively eliminate the generated water from the reactive sites. Moreover, it could precipitate from the reaction system with excellent recovery ratio (>99%) and be reused for ten times without any significant loss of activity.

The anion effect of the 5-ethylisoalloxazinium salts on their catalytic activity was investigated for the oxidation of sulfide with aq H2O2 in order to design more practical and safer flavinium salt catalysts that can replace the conventional perchlorate salt. The anions forming stronger conjugated acids were found to accelerate the catalytic sulfoxidation. The riboflavin-derived isoalloxazinium triflate salt was chosen as a readily accessible flavin with an efficient catalytic activity. In fact, the isoalloxazinium triflate 1b is an excellent organocatalyst for the chemoselective oxidations of a sulfide to a sulfoxide, Bayer–Villiger reaction of a cyclobutanone to a γ-butyrolactone, Dakin reaction of an arylaldehyde to a phenol, and oxidation of an aldehyde to a carboxylic acid using aq H2O2 as a terminal oxidant under mild conditions.

A silver-triflate catalyzed cascade of in situ-oxidation and allylation of arylbenzylamines is reported. The 2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoroborate is employed as a mild oxidant which is compatible with both catalyst and ligand. Racemic BINAP is also utilized to assist with the catalyst in regulating the yields of products. Various homoallylic amines are obtained in 39–99% yields.

A highly efficient method to afford 2,3-unsaturated glycosides was described. In the presence of Hafnium(IV) triflate, a variety of 2,3-unsaturated- O - and S -glycosides have been obtained by stereoselective glycosylation of 3,4,6-tri- O -acetyl- d -glucal and hexa- O -acetyl- d -lactal with various acceptors in good isolated yields.

Herein, we wish to report the scandium triflate catalyzed synthesis of novel dibenzo[b,f][1,5]oxazocin-6-ones in PEG-400 as a greener medium. Using this simple and greener protocol, for the very first time we have constructed novel eight-membered heterocyclic compounds in good yields. The PEG-Sc(OTf)3 catalytic system can be reused for four consecutive runs without any significant loss of its catalytic activity.

Coumarins are a well-known class of natural occurring and semi-synthetic products with reported important and effective pharmacological activities. In this Letter an improved method for the chemical synthesis of such compounds is described. Coumarins have been obtained in good to excellent yields under microwave irradiation and solvent-free conditions in a short time from differently substituted phenols and propiolic acids used as starting materials in the presence of Yb(OTf) 3 hydrate 10% mol as the catalyst.

This Letter describes the synthesis of olefins by coupling of electron deficient sulfonylhydrazones with aryl sulfinate salts in the presence of a palladium(II) catalyst under aerobic conditions. This methodology obviates the need for preparation of an organometallic and separate activation of the ketone starting material via a vinyl halide or triflate. The oxidant, reagent stoichiometry, and the electronics of the sulfinate coupling partner are reported.

Described herein is the use of copper triflate to efficiently catalyze a [3+2] annulation of propargylic acetates with N-alkylanilines in the presence of trimethylsilyl chloride (Me3SiCl) to produce 2,3-disubstituted indole derivatives. Also, the copper(II) catalyst efficiently promoted an aza-Claisen rearrangement of N-arylated propargylic amines involving a 3-aza-1,5-enyne skeleton.

Copper(II) triflate catalyzed stereoselective glycosylation of 2-iodo-glycosyl acetate donor is reported. Anomeric activation of 2-deoxy-1- O -acetyl sugar employing Cu(OTf) 2 found to be an attractive as well effective alternative reagent to the most frequently used triflic acid (TfOH) source such as TMSOTf or TBSOTf. Scope of the reaction was explored for various aglycones. This protocol involves simple reaction operation, employs less expensive and non-toxic reagent system, and enables the stereoselective preparation of 2-deoxy-2-iodo-glycosides. Furthermore, CuI/NaIO 4 in the presence of AcOH at ambient temperature promoted the regioselective iodoacetoxylation of various glycals to access 2-iodo-glycosyl acetates.

Palladium-catalyzed chemoselective and regioselective cross-coupling reactions of 2,3-dichloro-1,4-(trifluoromethanesulfonyloxy)naphthalene with aryl boronic acids selectively afforded a variety of mono-, di-, and tetraphenylnaphthalenes. These reactions proceeded with excellent chemoselectivity in favor of the triflate functional group at the C-1 and C-4 positions of naphthalene.

2-Amino-4H-pyrane derivatives are nowadays well recognized as valuable scaffold in drug discovery. In this manuscript a new and improved multicomponent process for the chemical synthesis of the title compounds is described. β-Dicarbonyl and activated cyanomethylene compounds, and aromatic, aliphatic or α,β-unsaturated aldehydes have been subjected to a three-component reaction under the catalysis of ytterbium triflate hydrate under solvent-free conditions at 50 °C, and by application of microwaves and ultrasounds. Of the three methodologies employed, the reaction in neat performed in a flask with magnetic stirring proved to be by far the most efficient, providing the desired adducts in very good yields (85–91%). The experimental protocol set-up in this study was applied without significant differences in terms of yields to aromatic aldehydes having electron withdrawing or electron-donating substituents, as well as to aliphatic and α,β-unsaturated ones. Moreover ytterbium triflate has been easily recovered from each reaction media and reused without appreciable loss of its catalytic activity.

The use of di-tert-butylsilyl bis(trifluoromethanesulfonate) has been used to form cyclic protecting groups for substituted salicylic acids. The reaction works well in the presence of a variety of electron-donating groups (EDG) affording the protected compounds in moderate to excellent yields (70–99%) in most cases. In addition, a handful of electron-withdrawing groups (EWG) also provided the corresponding protected silylene derivatives in good yields (77–83%). However, substrates bearing additional ortho -substitution of the carboxylic acid moiety as well as strongly deactivating groups on the aromatic ring did not undergo reaction.

Maltol triflate 3 undergoes palladium-mediated carbon-carbon bond formation with styrene, boronic acids and alkynes. Benzyl ether 2 can be acylated. The acylation products can be readily converted into furo[3,2-b]pyranones.

Thiocyano-group widely exist in natural products and drug structures. A novel one-pot synthesis of alkynylthiocyanates from terminal alkynes, [hydroxy(tosyloxy)iodo]benzene and potassium thiocyanate by phase-transfer reagent involving the hypervalent iodine intermediates in transition metal-free conditions was developed. The internal alkynylthiocyanates could be used to synthesize some important compounds such as 5-thiocyanato-1,2,3-triazoles and (Z)-α-thiocyanato-vinyl trifluoromethanesulfonate.

A series of α- and β-5-halo-2′-deoxyuridine derivatives were prepared with high anomeric selectivity using the conventional silylbase glycosylation method and taking advantage of the 3′- O -( N -acetyl)glycyl protection group and temperature control. Reactions performed at −7 °C gave as much as 87% of the β-anomers, while an overnight reaction at 30 °C gave up to 95% of the α-anomers.

A number of nitrosonium and nitronium salts were probed as reagents for the heterocyclization of 1-bromo-1-fluorocyclopropanes in the presence of organic nitriles to give pyrimidine N -oxides. Nitronium triflate, either preformed or generated in situ from nitric and triflic acids, was shown to be the most efficient reagent for this reaction, affording a mild and convenient procedure for the synthesis of 4-halogenopyrimidine derivatives. X-ray crystallography was used to confirm the ionic structure of nitronium triflate (NO 2 + )(CF 3 SO 3 − ).

A metal-free method for the N-arylation of amidines and N,N-disubstituted amidines using o-silylaryl triflate under very mild reaction conditions is developed. The reactions are compatible with a variety of functional groups. Imines can also be N-arylated by this method. Preparation of substituted phenanthridines via a Pd catalyzed intramolecular cyclization of the iodine containing N-arylation product is demonstrated.

Xanthones represent a class of naturally occurring compounds with valuable and promising reported pharmacological activities. One of the main disadvantages in the use of such products is related to the difficulties in their chemical synthesis. In this Letter a new and improved method for the chemical synthesis of xanthones is described. The title compounds have been synthesized in good yields under microwave irradiation from substituted 2-hydroxybenzoic acids and phenols in the presence of Yb(OTf)3 hydrate as the catalyst.

Arylated quinolines were prepared by Suzuki–Miyaura cross-coupling reactions of 5-bromoquinolin-8-yl trifluoromethanesulfonate. The reactions proceeded with very good chemoselectivity in favor of the bromide group.

Erbium trifluoromethanesulfonate is found to be a good catalyst for the Friedel–Crafts acylation of arenes containing electron-donating substituents using aromatic carboxylic acids as the acylating agents under microwave irradiation. An effective, rapid and waste-free method allows the preparation of a wide range of aryl ketones in good yields and in short reaction times with minimum amounts of waste.

The catalytic Diels–Alder reaction of siloxyvinylindole and cyclic Z-olefin derived from pyroglutamic acid gave optically active substituted hydrocarbazoles. The exo/endo selectivity of this reaction could be controlled by using an appropriate Lewis acid. Scandium triflate gave high exo-selectivity and copper triflate gave moderate endo-selectivity. Subsequent stereoselective alkylation of the cycloadduct led to the synthesis of highly substituted hydrocarbazoles with five continuous chiral centers including a quaternary carbon.

Solvolysis studies of pivaloyl triflate were performed using ionic liquid/methanol solvent mixtures. The rearranged carbocation intermediate reacts with methanol via nucleophilic attack or elimination of a proton. Relative amounts of products were determined through 1 H NMR analysis. For most ionic liquids, increasing the ionic liquid:methanol ratio leads to increased yields of elimination product. Product ratios vary based on Kamlet–Taft solvatochromic parameters of hydrogen bond donating and accepting ability of the ionic liquid.

A synthetic route to prepare highly substituted pyrrole derivatives efficiently in moderate to good yields via the Yb(OTf)3-catalyzed cyclization of 1,4-propargylic diols with aryl sulfonamides is reported herein. The present synthetic method offers an operationally simple and convenient route to pyrroles under mild conditions that does not require the exclusion of air and moisture.

The reaction of 1,1-dichloro-2-vinylcyclopropane with arenes under the action of the superacid TfOH afforded 3-aryl-1,1-dichloropent-1-enes (25–43% yield), as the products of cyclopropane ring opening. The reaction of 1,1-dichloro-2-methyl-2-vinylcyclopropane was realized as a two-step procedure, including initial in situ generation of the corresponding triflate, 5,5-dichloro-4-methylpent-4-en-2-yl trifluoromethanesulfonate, from the cyclopropane and TfOH, followed by reaction with arenes and TfOH to give 1,1-dichloro-2-methyl-4-arylpent-1-enes (30–68% yield).

The Ytterbium (III) triflate catalyzed Hantzsch synthesis allows for the preparation of sterically hindered 4-isoxazolyl-1,4-dihydropyridines in moderate to good yields. Asymmetric organocatalysis with (R)-4-Oxo-2,6-bis-(2,4,6-triisopropyl-phenyl)-3,5-dioxa-4l5-phospha-cyclohepta[2,1-a;3,4-a’]dinaphthalen-4-ol (R-TRIP) produces moderate yields of chiral 4-isoxazolyl-quinolones with high enantioselectivity.

2-Allyloxypyridinium triflate is formed in situ by treating a mixture of 2-allyloxypyridine, a carboxylic acid, and toluene with methyl triflate. Subsequent warming of the reaction mixture in the presence of potassium carbonate leads to efficient formation of allyl esters in good to excellent yields.

2,4- and 2,4,5-substituted oxazoles were prepared from a broad range of bromo-ketones and amides in high yield and purity.

Silica supported lanthanum triflate (Ln(OTf) 3 -SiO 2 ) promoted synthesis of 5-substituted 1H -tetrazoles via [3+2] cycloaddition between aromatic/heteroaromatic nitriles and sodium azide is a high product yielding, facile, and straightforward procedure. Non toxicity, recovery, and reusability for three continuous cycles are the noteworthy features of the currently employed heterogeneous catalyst.

Various 5-substituted 1H-tetrazoles were synthesized from aryl nitriles, alkyl nitriles, and vinyl nitriles reacting with sodium azide. The tetrazoles were recovered in high yield under mild conditions when the reaction was catalyzed by ytterbium triflate hydrate in dimethylformamide. Other rare-earth and post-transition metal catalysts were also investigated.