Recent advances in hypervalent iodine(III)-catalyzed functionalization of alkenes

• Xiang Li,
• Pinhong Chen and
• Guosheng Liu

Beilstein J. Org. Chem. 2018, 14, 1813–1825, doi:10.3762/bjoc.14.154

• environment at the iodine center. Mechanistically, the iodine(III) 16 is activated by triflic acid generating a free coordination site at the iodine(III) center [54]. The coordination of the alkene to the activated iodine(III) center generates the required prochiral face differentiation and the nucleophilic

Synthesis and stability of strongly acidic benzamide derivatives

• Frederik Diness,
• Niels J. Bjerrum and
• Mikael Begtrup

Beilstein J. Org. Chem. 2018, 14, 523–530, doi:10.3762/bjoc.14.38

• enable their incorporation into functional materials (e.g., polymers), these acids need additional functionality in the form of a reactive group, and the chemistry applied for functionalization must be compatible with their strong acidic nature. Many types of strong organic acids such as triflic acid (7

Aminosugar-based immunomodulator lipid A: synthetic approaches

• Alla Zamyatina

Beilstein J. Org. Chem. 2018, 14, 25–53, doi:10.3762/bjoc.14.3

• deprotected by treatment with tetrabutylammonium fluoride buffered with acetic acid, and the resulting lactol was converted to the imidate donor 11 which was coupled to the orthogonally protected acceptor, an azide 12, using triflic acid as promotor (Scheme 2). Subsequent hydrolytic cleavage of the

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

Intramolecular glycosylation

• Xiao G. Jia and
• Alexei V. Demchenko

Beilstein J. Org. Chem. 2017, 13, 2028–2048, doi:10.3762/bjoc.13.201

• alcohol showed good selectivity (α/β = 4.8:1) when boronic acid and NBS were employed. Control experiments with a thiophenyl or a thiobenzyl leaving group showed lower stereoselectivities and a slight reduction in yields. The addition of triflic acid or silver triflate resulted in a significant reduction

1,3-Dibromo-5,5-dimethylhydantoin as promoter for glycosylations using thioglycosides

• Fei-Fei Xu,
• Claney L. Pereira and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2017, 13, 1994–1998, doi:10.3762/bjoc.13.195

• GmbH, Magnusstraße 11, 12489 Berlin, Germany 10.3762/bjoc.13.195 Abstract 1,3-Dibromo-5,5-dimethylhydantoin (DBDMH), an inexpensive, non-toxic and stable reagent, is a competent activator of thioglycosides for glycosidic bond formation. Excellent yields were obtained when triflic acid (TfOH) or

Synthesis of alkynyl-substituted camphor derivatives and their use in the preparation of paclitaxel-related compounds

• M. Fernanda N. N. Carvalho,
• Rudolf Herrmann and
• Gabriele Wagner

Beilstein J. Org. Chem. 2017, 13, 1230–1238, doi:10.3762/bjoc.13.122

• /13C NMR experiments, and by comparison with relatively similar compounds obtained in the reaction of the bis(phenylalkynyl)-derivative of 4a with triflic acid [26], or with K[ReO4] [27]. The polycyclic carbon skeleton in these is identical, but the latter compounds are protonated at the sulfonimide

Regioselective (thio)carbamoylation of 2,7-di-tert-butylpyrene at the 1-position with iso(thio)cyanates

• Anna Wrona-Piotrowicz,
• Marzena Witalewska,
• Janusz Zakrzewski and
• Anna Makal

Beilstein J. Org. Chem. 2017, 13, 1032–1038, doi:10.3762/bjoc.13.102

• reported an efficient method for the synthesis of pyrene-1-carbothioamides via reaction of pyrene with isothiocyanates in the presence of trifluoromethanesulfonic (triflic) acid (TfOH) [11][12]. Since 2 was used as a starting material in the syntheses of various pyrenyl fluorophores exhibiting unique

• sterically hindered pyrene 1-position, whereas the bulkier protonated acetyl trifluoroacetate (the postulated electrophile in the examined Friedel–Crafts acylation) attacks sterically the less hindered 4-position. Conclusion We found that triflic acid-promoted (thio)carbamoylation of 2 with aliphatic iso

• , 879, 733; anal. calcd. for C25H25N: C, 88.45; H, 7.42; N, 4.13; found: C, 88.39; H, 7.51; N, 4.06. 4-Acetyl-2,7-di-tert-butylpyrene (6). 2,7-Di-tert-butylpyrene (2, 628 mg, 2 mmol) and triflic acid (174 μL, 2 mmol) were added at 0 °C to a solution of acetic acid (126 μL, 2.2 mmol) and trifluoroacetic

Metal-free hydroarylation of the side chain carbon–carbon double bond of 5-(2-arylethenyl)-3-aryl-1,2,4-oxadiazoles in triflic acid

• Anna S. Zalivatskaya,
• Dmitry S. Ryabukhin,
• Marina V. Tarasenko,
• Alexander Yu. Ivanov,
• Irina A. Boyarskaya,
• Elena V. Grinenko,
• Ludmila V. Osetrova,
• Eugeniy R. Kofanov and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2017, 13, 883–894, doi:10.3762/bjoc.13.89

• University, Universitetskaya nab., 7/9, Saint Petersburg, 199034, Russia Institute of Synthetic Rubber, Gapsalskaya str., 1, Saint Petersburg, 198035, Russia 10.3762/bjoc.13.89 Abstract The metal-free reaction of 5-(2-arylethenyl)-3-aryl-1,2,4-oxadiazoles with arenes in neat triflic acid (TfOH, CF3SO3H

• , N4,C-diprotonated forms of oxadiazoles are the electrophilic intermediates in this reaction. Keywords: Friedel–Crafts reaction; hydroarylation; oxadiazoles; superelectrophilic activation; triflic acid; Introduction Oxadiazoles are an important class of heterocyclic compounds and great attention has

Total synthesis of a Streptococcus pneumoniae serotype 12F CPS repeating unit hexasaccharide

• Peter H. Seeberger,
• Claney L. Pereira and
• Subramanian Govindan

Beilstein J. Org. Chem. 2017, 13, 164–173, doi:10.3762/bjoc.13.19

• containing a C3 hydroxy group [28]. Glycosylation of disaccharide 34 using galactose building block 9, activated by NIS/triflic acid, produced trisaccharide 35 with high α-selectivity by virtue of the C4-participating benzoyl ester protecting group of 9 [36]. Trisaccharide 35 was transformed into a

The digital code driven autonomous synthesis of ibuprofen automated in a 3D-printer-based robot

• Philip J. Kitson,
• Stefan Glatzel and
• Leroy Cronin

Beilstein J. Org. Chem. 2016, 12, 2776–2783, doi:10.3762/bjoc.12.276

• (triflic) acid (CF3SO3H) as the Lewis acid catalyst to yield 4-isobutylpropiophenone (2). Once this is complete a solution of di(acetoxy)phenyl iodide (PhI(OAc)2) and trimethyl orthoformate (TMOF) in methanol (MeOH) is added to the reaction mixture in order to induce a 1,2-aryl migration to produce the

• dropwise addition of triflic acid over the course of 10 min to minimise the exotherm produced. Once this process was completed the dispensing needle is raised from the aperture and the reaction is agitated. After 18 h of agitation the needle corresponding to the PhI(OAc)2/TMOF solution is lowered into the

Superelectrophilic activation of 5-hydroxymethylfurfural and 2,5-diformylfuran: organic synthesis based on biomass-derived products

• Dmitry S. Ryabukhin,
• Dmitry N. Zakusilo,
• Mikhail O. Kompanets,
• Anton A.Tarakanov,
• Irina A. Boyarskaya,
• Tatiana O. Artamonova,
• Mikhail A. Khohodorkovskiy,
• Iosyp O. Opeida and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2016, 12, 2125–2135, doi:10.3762/bjoc.12.202

• Minerals, L.M. Litvinenko Institute of Physical Organic and Coal Chemistry of NASU, Naukova St., 3a, Lviv, 79053, Ukraine 10.3762/bjoc.12.202 Abstract The reaction of 5-hydroxymethylfurfural (5-HMF) with arenes in superacidic trifluoromethanesulfonic acid (triflic acid, TfOH) as the solvent at room

Reactions of N,3-diarylpropiolamides with arenes under superelectrophilic activation: synthesis of 4,4-diaryl-3,4-dihydroquinolin-2(1H)-ones and their derivatives

• Larisa Yu. Gurskaya,
• Diana S. Belyanskaya,
• Dmitry S. Ryabukhin,
• Denis I. Nilov,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2016, 12, 950–956, doi:10.3762/bjoc.12.93

• )-ones [12][13]. The main goal of this work was a systematic study on reactions of 3-aryl-N-(aryl)propiolamides with arenes under the action of the Brønsted superacid TfOH (CF3SO3H, triflic acid), strong Lewis acids AlX3 (X = Cl, Br), or the conjugate Brønsted–Lewis superacid TfOH–SbF5. Results and

• based on the reaction of 3-aryl-N(aryl)propiolamides with arenes under superelectrophilic activation in triflic acid has been developed. The synthetic potential of the obtained dihydroquinolinones has been demonstrated by their transformations into N-acyl, N-formyl, and N-diphenylmethyl derivatives

Elucidation of a masked repeating structure of the O-specific polysaccharide of the halotolerant soil bacteria Azospirillum halopraeferens Au4

• Elena N. Sigida,
• Yuliya P. Fedonenko,
• Alexander S. Shashkov,
• Nikolay P. Arbatsky,
• Evelina L. Zdorovenko,
• Svetlana A. Konnova,
• Vladimir V. Ignatov and
• Yuriy A. Knirel

Beilstein J. Org. Chem. 2016, 12, 636–642, doi:10.3762/bjoc.12.62

• residue (~65%), are shown in italics. Keywords: Azospirillum halopraeferens; bacterial polysaccharide structure; lipopolysaccharide; O-specific polysaccharide; Smith degradation; triflic acid solvolysis; Introduction Rhizobacteria of the genus Azospirillum are isolated from a wide variety of

Friedel–Crafts-type reaction of pyrene with diethyl 1-(isothiocyanato)alkylphosphonates. Efficient synthesis of highly fluorescent diethyl 1-(pyrene-1-carboxamido)alkylphosphonates and 1-(pyrene-1-carboxamido)methylphosphonic acid

• Anna Wrona-Piotrowicz,
• Janusz Zakrzewski,
• Anna Gajda,
• Tadeusz Gajda,
• Anna Makal,
• Arnaud Brosseau and
• Rémi Métivier

Beilstein J. Org. Chem. 2015, 11, 2451–2458, doi:10.3762/bjoc.11.266

• useful method for the synthesis of aromatic secondary thioamides [1][2][3][4][5][6]. Our group [7] and others [8] have recently described an efficient modification of this method by using trifluoromethanesulfonic (triflic) acid as a promoter. Furthermore, we reported a simple procedure for the oxidative

Synthesis of D-fructose-derived spirocyclic 2-substituted-2-oxazoline ribosides

• Madhuri Vangala and
• Ganesh P. Shinde

Beilstein J. Org. Chem. 2015, 11, 2289–2296, doi:10.3762/bjoc.11.249

• -protected 1,2-O-isopropylidene-β-D-fructofuranose derivatives with triflic acid (1.5 equiv) using nitriles (10 equiv) at −20 °C to rt in DCM [37]. Although fructopyranoses were shown to react with acetonitrile, propionitrile and benzonitrile, only one example of the corresponding fructofuranose with

The synthesis of active pharmaceutical ingredients (APIs) using continuous flow chemistry

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2015, 11, 1194–1219, doi:10.3762/bjoc.11.134

• order to avoid downstream incompatibilities. The initial step was a Friedel–Crafts acylation of isobutylbenzene (10) with propionic acid (11) in the presence of excess triflic acid (12). The transformation was found to work very effectively and the acid catalyst was also tolerated in the subsequent 1,2

• the existing manufacturing routes which have been highly refined and optimised [49][50][51]. Although modern reagents such as hypervalent iodine and triflic acid represent very valuable additions to the chemists’ repertoire they are also inherently expensive and difficult to source at scale. In

Novel carbocationic rearrangements of 1-styrylpropargyl alcohols

• Christine Basmadjian,
• Fan Zhang and
• Laurent Désaubry

Beilstein J. Org. Chem. 2015, 11, 1017–1022, doi:10.3762/bjoc.11.114

• degraded in presence of triflic acid (entries 10 and 11, Table 2). Thus, the presence of methanol seems necessary for the cyclization to occur, perhaps by stabilizing an intermediate. Replacement of dichloroethane by nitromethane slightly decreased the yield of 22, and suppressed the formation of furan 23

Diastereoselective and enantioselective conjugate addition reactions utilizing α,β-unsaturated amides and lactams

• Katherine M. Byrd

Beilstein J. Org. Chem. 2015, 11, 530–562, doi:10.3762/bjoc.11.60

• circumvent the issues raised by the Hii study [241], they added 1 equiv of triflic acid to 1.5 equiv of aniline to create the anilinium salt. The addition of the acid, along with the use of 133 as the chiral Lewis acid complex provided the 1,4-addition products in good to excellent yields and excellent

A general metal-free approach for the stereoselective synthesis of C-glycals from unactivated alkynes

• Shekaraiah Devari,
• Manjeet Kumar,
• Ramesh Deshidi,
• Masood Rizvi and
• Bhahwal Ali Shah

Beilstein J. Org. Chem. 2014, 10, 2649–2653, doi:10.3762/bjoc.10.277

• glucal. As expected [40][41], the reaction on heating at 70 °C for 3 h gave the iodinated phenylacetylene (Scheme 3, reaction 1 & Figure S1, Supporting Information File 1). Thus, the triflic acid generated in situ consequent to the formation of trimethylsilylacetylene activates the tri-O-acetyl-D-glucal

(CF₃CO)₂O/CF₃SO₃H-mediated synthesis of 1,3-diketones from carboxylic acids and aromatic ketones

• JungKeun Kim,
• Elvira Shokova,
• Victor Tafeenko and
• Vladimir Kovalev

Beilstein J. Org. Chem. 2014, 10, 2270–2278, doi:10.3762/bjoc.10.236

• application of the proposed protocol allowed for the synthesis of selected polysubstituted pyrazoles in a one-pot procedure directly from acids and ketones. Keywords: Claisen condensation; 1,3-diketones; heterocycles; triflic acid; trifluoroacetic acid anhydride; Introduction 1,3-Diketones represent one of

• partially self-acylated under the reaction conditions. A probable mechanism of the reaction of ketone acylation by acids in TFAA/TfOH media may be that after the acyl trifluoroacetates are generated in situ, triflic acid becomes involved in the enolization of ketones and increases the acylating ability of

• chemistry. Experimental General procedure for the synthesis of diketones: A solution of carboxylic acid (1 mmol), ketone (1 mmol, if required) and TFAA (0.85 mL, 6 mmol) in dichloromethane (1 mL) was stirred for 15 min at rt. The required quantity of triflic acid (usually 44 μL, 0.5 mmol) was then added

A new approach for the synthesis of bisindoles through AgOTf as catalyst

• Jorge Beltrá,
• M. Concepción Gimeno and
• Raquel P. Herrera

Beilstein J. Org. Chem. 2014, 10, 2206–2214, doi:10.3762/bjoc.10.228

• indole (4a) and aldehyde 5a, one with HOTf (1 mol %) and the other with AgOTf (1 mol %), showing that the reaction rate of the process catalyzed by triflic acid is higher (after 6 h the reaction is finished). This is also in agreement with the results observed by Hartwig and co-workers [54]. These

• findings indicate that AgOTf is the mean catalyst of the process, because although triflic acid could participate in the activation process, it would be consumed in the reaction with the produced AgOH to regenerate AgOTf. Conclusion In summary, we have reported for the first time an unprecedented approach

Allenylphosphine oxides as simple scaffolds for phosphinoylindoles and phosphinoylisocoumarins

• G. Gangadhararao,
• Ramesh Kotikalapudi,
• M. Nagarjuna Reddy and
• K. C. Kumara Swamy

Beilstein J. Org. Chem. 2014, 10, 996–1005, doi:10.3762/bjoc.10.99

• in isolation. Analogous products could also be isolated using the P(III) precursor (OCH2CMe2CH2O)PCl (see Supporting Information File 1 for details). In our attmept to obtain phosphorus-free 2-alkylindole from 17 in the presence of triflic acid (as a solvent; 100 °C) led to a mixture of products in

New developments in gold-catalyzed manipulation of inactivated alkenes

• Michel Chiarucci and
• Marco Bandini

Beilstein J. Org. Chem. 2013, 9, 2586–2614, doi:10.3762/bjoc.9.294

• PPh3AuOTf in the addition of various nucleophiles to alkenes, demonstrating how the gold complex and triflic acid can exhibit complementary efficiency [17]. This finding suggests that although Brønsted acid co-catalysis is a possible competing process, under suitable conditions the gold-catalyzed pathway is

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

• substituted Grignard reagent 1.26. A Friedel–Crafts type acylation promoted by either triflic acid or polyphosphoric acid (PPA) furnishes the tricyclic structure 1.28 which upon N-demethylation affords clarinex (1.22). One of the top-selling classes of pharmaceuticals containing the pyridine ring are the