Diastereoselective synthesis of 3,4-dihydro-2H-pyran-4-carboxamides through an unusual regiospecific quasi-hydrolysis of a cyano group

• Mikhail Yu. Ievlev,
• Oleg V. Ershov,
• Mikhail Yu. Belikov,
• Angelina G. Milovidova,
• Viktor A. Tafeenko and
• Oleg E. Nasakin

Beilstein J. Org. Chem. 2016, 12, 2093–2098, doi:10.3762/bjoc.12.198

• derivatives 3 we carried out the reaction of specially prepared 6-imino-2,7-dioxabicyclo[3.2.1]octane-3,3,4-tricarbonitrile 3h [21] with dry trifluoroacetic acid under anhydrous conditions (Table 2, entry 6). The successful implementation of this process and isolation of product 2h with good yield indicate

Three-component synthesis of highly functionalized aziridines containing a peptide side chain and their one-step transformation into β-functionalized α-ketoamides

• Lena Huck,
• Juan F. González,
• Elena de la Cuesta and
• J. Carlos Menéndez

Beilstein J. Org. Chem. 2016, 12, 1772–1777, doi:10.3762/bjoc.12.166

• acidic conditions either failed to give any reaction at room temperature or afforded complex mixtures when heated. After some experimentation, we finally discovered that treatment of compound 2e with trifluoroacetic acid in dichloromethane at 45 °C gave an excellent yield of the β-trifluoroacetamido-α

• trifluoroacetate liberated in the previous step, to give 6. Alternatively, loss of a molecule of methanol from starting compound 2 would lead to intermediate 5 (see Scheme 3), whose reaction with trifluoroacetic acid would furnish 9. Neber-type chemistry would afford the oxonium species 10, which would finally be

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

• oxidative fragmentation at the bridgehead position of adamantanes 157a,b. The reaction employed the trifluoroperacetic acid (TFPAA)/trifluoroacetic acid (TFAA) system and afforded compounds 158a,b in high yields (Scheme 46) [300]. This method for the insertion of an oxygen atom was applied to the oxidation

Methylpalladium complexes with pyrimidine-functionalized N-heterocyclic carbene ligands

• Dirk Meyer and
• Thomas Strassner

Beilstein J. Org. Chem. 2016, 12, 1557–1565, doi:10.3762/bjoc.12.150

• group uses a mixture of trifluoroacetic acid (TFA) and its anhydride (TFAA) as solvents. It has the advantage that the formed ester can be separated and hydrolyzed, followed by recycling of the free acid which potentially can be reused in the process [24][25][26][27][28][29][30]. Contrary to the

• CDCl3, where two different signals for the m-pyrimidine protons are observed. We recently reported that the dihalogenato complexes are active catalysts of the methane CH activation in trifluoroacetic acid [34]. Under the reaction conditions it seems likely, that an exchange of the chloro against a

• ). We could also confirm the formation of the desired product by a solid state structure (Figure 4). Typical reaction conditions of the catalytic CH activation are 30 atmospheres of methane under strongly oxidizing conditions (potassium peroxodisulfate, trifluoroacetic acid and its anhydride), where

Synthesis of 2-substituted tetraphenylenes via transition-metal-catalyzed derivatization of tetraphenylene

• Shulei Pan,
• Hang Jiang,
• Yanghui Zhang,
• Yu Zhang and
• Dushen Chen

Beilstein J. Org. Chem. 2016, 12, 1302–1308, doi:10.3762/bjoc.12.122

• obtained in 20% yield (Table 5, entry 1). While the yield was improved to 42% in the presence of 2.0 equiv DMSO (Table 5, entry 2), it decreased when 4.0 equiv DMSO were used (Table 5, entry 3). Since the solubility of 1 in trifluoroacetic acid is low, we envisaged that the addition of co-solvents would

Multicomponent reactions: A simple and efficient route to heterocyclic phosphonates

• Mohammad Haji

Beilstein J. Org. Chem. 2016, 12, 1269–1301, doi:10.3762/bjoc.12.121

• -phosphonates: A one-pot three-component synthesis of N-arylisoquinolone-1-phosphonates 119 through the Kabachnik–Fields reaction of ethyl 2-(2-formyl-4,5-dimethoxyphenyl)acetate (116) with anilines 117 and triethyl phosphite in the presence of trifluoroacetic acid as catalyst has been reported by Borse et al

Synthesis, fluorescence properties and the promising cytotoxicity of pyrene–derived aminophosphonates

• Jarosław Lewkowski,
• Maria Rodriguez Moya,
• Anna Wrona-Piotrowicz,
• Janusz Zakrzewski,
• Renata Kontek and
• Gabriela Gajek

Beilstein J. Org. Chem. 2016, 12, 1229–1235, doi:10.3762/bjoc.12.117

• (3Ai) was obtained, when the Kabachnik–Fields reaction was carried out in the presence of a catalytic amount of trifluoroacetic acid in refluxing acetonitrile. The same procedure, i.e., the Kabachnik–Fields reaction in the presence of trifluoroacetic acid, but in refluxing methanol has been

A cross-metathesis approach to novel pantothenamide derivatives

• Jinming Guan,
• Matthew Hachey,
• Lekha Puri,
• Vanessa Howieson,
• Kevin J. Saliba and
• Karine Auclair

Beilstein J. Org. Chem. 2016, 12, 963–968, doi:10.3762/bjoc.12.95

• next reaction without further purification due to its low stability. The required amine 14 to be coupled to 13 was synthesized from Boc-protected β-alanine and pentylamine using a method reported by Hoegl et al. [11]. Deprotection of the Boc group with trifluoroacetic acid (TFA) provided the free amine

Gold-catalyzed direct alkynylation of tryptophan in peptides using TIPS-EBX

• Gergely L. Tolnai,
• Jonathan P. Brand and
• Jerome Waser

Beilstein J. Org. Chem. 2016, 12, 745–749, doi:10.3762/bjoc.12.74

• modified reaction conditions (10 mol % AuCl(SMe2), three equivalents TIPS-EBX (1a) and 2 mol % trifluoroacetic acid as co-catalyst) [39]. They also demonstrated that the obtained silylalkyne products can be easily deprotected with fluoride sources to allow bioconjugation via cycloaddition with azides

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

• hydrolysis of the lipopolysaccharide isolated by the phenol–water extraction from the halotolerant soil bacteria Azospirillum halopraeferens type strain Au4. The polysaccharide was studied by sugar and methylation analyses, selective cleavages by Smith degradation and solvolysis with trifluoroacetic acid

Simple activation by acid of latent Ru-NHC-based metathesis initiators bearing 8-quinolinolate co-ligands

• Julia Wappel,
• Roland C. Fischer,
• Luigi Cavallo,
• Christian Slugovc and
• Albert Poater

Beilstein J. Org. Chem. 2016, 12, 154–165, doi:10.3762/bjoc.12.17

• stirred methanol and dried. Noteworthy, hydrochloric acid is the only acid which activates the preinitiators under investigation. Addition of other acids (or acid liberating reagents) such as acetyl chloride or trifluoroacetic acid, were not able to promote the polymerization. Also the addition of

Diastereoselective Ugi reaction of chiral 1,3-aminoalcohols derived from an organocatalytic Mannich reaction

• Samantha Caputo,
• Andrea Basso,
• Lisa Moni,
• Renata Riva,
• Valeria Rocca and
• Luca Banfi

Beilstein J. Org. Chem. 2016, 12, 139–143, doi:10.3762/bjoc.12.15

• , by additional crystallization, affording these key intermediates in high ee and de (syn relative configuration, see Supporting Information File 1). The tert-butyl urethane was then deblocked with trifluoroacetic acid. Neutralization and extraction afforded crude aminoalcohols 5a–e, that were directly

Copper-catalyzed intermolecular oxyamination of olefins using carboxylic acids and O-benzoylhydroxylamines

• Brett N. Hemric and
• Qiu Wang

Beilstein J. Org. Chem. 2016, 12, 22–28, doi:10.3762/bjoc.12.4

• efficiencies were observed in the reactions with more acidic benzoic acids, indicating a correlation of their reactivity to their acidity which remains to be further clarified [44]. Furthermore, when trifluoroacetic acid was employed as an oxygen source, the free 1,2-amino alcohol 4g was isolated, possibly due

Selectively fluorinated cyclohexane building blocks: Derivatives of carbonylated all-cis-3-phenyl-1,2,4,5-tetrafluorocyclohexane

• Mohammed Salah Ayoup,
• David B. Cordes,
• Alexandra M. Z. Slawin and
• David O'Hagan

Beilstein J. Org. Chem. 2015, 11, 2671–2676, doi:10.3762/bjoc.11.287

• trifluoroacetic acid (TFA) or 6 M HCl in dioxane [10] gave the corresponding benzoic acids 11, 12, and 13 as illustrated in Scheme 1. Direct palladium catalysed formylation of aryl iodides 6/7 as a mixture was explored using Pd(PPh3)4, Bu4SnH and CO [11]. This generated benzaldehyde derivatives 14 and 15 in a 1:3

Carbon–carbon bond cleavage for Cu-mediated aromatic trifluoromethylations and pentafluoroethylations

• Tsuyuka Sugiishi,
• Hideki Amii,
• Kohsuke Aikawa and
• Koichi Mikami

Beilstein J. Org. Chem. 2015, 11, 2661–2670, doi:10.3762/bjoc.11.286

• microreactor, a new protocol for scalable aromatic trifluoromethylation was developed. From a mechanistic aspect, Vicic and co-workers explored the direct generation of CF3Cu from CF3CO2Cu. The use of (N-heterocyclic carbene)copper-trifluoroacetates prepared from trifluoroacetic acid (TFA) was investigated in

• , such as perfluoroalkyl acetates, trifluoroacetic acid, chlorodifluoroacetates, trifluoromethyl ketones and hemiaminals of trifluoroacetaldehyde, are attractive perfluoroalkyl anion sources for aromatic perfluoroalkylation reactions. The generation of perfluoroalkylcopper from perfluoroalkyl carboxylic

• determined by 19F NMR analysis using CF3CH2OH as an internal standard. C–H trifluoromethylation of arenes using trifluoroacetic acid. CF3Cu generated from chlorofluoroacetate and CuI. [18F]Trifluoromethyation with difluorocarbenes for PET. aRadiochemical yield determined by HPLC. Trifluoromethylation with

Easy access to heterobimetallic complexes for medical imaging applications via microwave-enhanced cycloaddition

• Nicolas Desbois,
• Sandrine Pacquelet,
• Adrien Dubois,
• Clément Michelin and
• Claude P. Gros

Beilstein J. Org. Chem. 2015, 11, 2202–2208, doi:10.3762/bjoc.11.239

• trifluoroacetic acid, followed by oxidation under the action of DDQ. Cu and Ga complexes were prepared by the strategy outlined in Scheme 2. The insertion of Cu into corrole 1 was easily achieved with Cu(OAc)2·H2O in THF during 15 min. To obtain the gallium corrole 8b, free-base azidocorrole 1 was dissolved in a

• first dissolved in trifluoroacetic acid (TFA) and stirred at room temperature overnight. A brown oil was obtained upon concentration. The residue was then purified by flash chromatography. Chelation of Cu2+ with propargyl NOTA 4 was performed in aqueous solution by Cu(ClO4)2·6H2O. Purification of Cu

Investigation on the reactivity of α-azidochalcones with carboxylic acids: Formation of α-amido-1,3-diketones and highly substituted 2-(trifluoromethyl)oxazoles

• Kandasamy Rajaguru,
• Arumugam Mariappan,
• Rajendran Suresh,
• Periasamy Manivannan and
• Shanmugam Muthusubramanian

Beilstein J. Org. Chem. 2015, 11, 2021–2028, doi:10.3762/bjoc.11.219

• Abstract The reaction of α-azidochalcones with carboxylic acids has been investigated resulting in the formation of α-amido-1,3-diketones under microwave irradiation via in situ formation of 2H-azirine intermediates. An interesting reaction is described wherein, with trifluoroacetic acid at lower

• two steps following a literature procedure [29]. Results and Discussion The investigation was initiated by treating α-azidochalcone 1a (R1 = 4-Br, R2 = 4-OMe) with trifluoroacetic acid (2a). This acid was allowed to react with the azidochalcone at room temperature for 30 minutes and a low yield of 3a

• -azidochalcone 1a (R1 = 4-Br, R2 = 4-OMe) with trifluoroacetic acid under microwave conditions [33] at 100 °C for 2 minutes to obtain diketone 3a (79%) as a solid without any side products (Scheme 1). The 1H NMR spectrum of 3a exhibits a methine proton doublet at 6.78 ppm. In the 13C NMR spectrum, two carbonyl

Latent ruthenium–indenylidene catalysts bearing a N-heterocyclic carbene and a bidentate picolinate ligand

• Thibault E. Schmid,
• Florian Modicom,
• Adrien Dumas,
• Etienne Borré,
• Loic Toupet,
• Olivier Baslé and
• Marc Mauduit

Beilstein J. Org. Chem. 2015, 11, 1541–1546, doi:10.3762/bjoc.11.169

• , we proceeded to synthesize complex 4b, featuring the 5-bromo-2-picolinate moiety. Using a similar methodology, the desired complex was obtained with 42% yield. The activation of the new picolinic complex 4a was initially evaluated in the presence of trifluoroacetic acid (TFA), a Brønsted acid easy to

Synthesis and evaluation of the biostability and cell compatibility of novel conjugates of nucleobase, peptidic epitope, and saccharide

• Dan Yuan,
• Xuewen Du,
• Junfeng Shi,
• Ning Zhou,
• Abdulgader Ahmed Baoum,
• Khalid Omar Al Footy,
• Khadija Omar Badahdah and
• Bing Xu

Beilstein J. Org. Chem. 2015, 11, 1352–1359, doi:10.3762/bjoc.11.145

• chain from the resin with 95% trifluoroacetic acid (TFA) without N-protecting groups. Later, NAS was obtained by reacting D-glucosamine hydrochloride with the fully protected NA. After cleaving the protecting group on amino acids with 95% TFA, we used reversed-phase high-performance liquid

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

• with trifluoroacetic acid (TFA) in the presence of pentamethylbenzene to generate mycocyclosin (135, 74%) (Scheme 19). Wurtz coupling: The Wurtz reaction is one of the oldest methods to form a C–C bond in organic synthesis. Baker and co-workers [138] have reported the synthesis of cyclophanes 137 and

• acetylenedicarboxylate (DMAD) to deliver compounds 332a,b (77%). These DA adducts were irradiated in diethyl ether/dichloromethane (5:1) to offer the corresponding bioxaquadricyclane 333, subsequent thermolysis gave the bioxepine 334 (81%). Finally, aromatization of bioxepine 334 with trifluoroacetic acid (TFA

Gold-catalyzed formation of pyrrolo- and indolo-oxazin-1-one derivatives: The key structure of some marine natural products

• Sultan Taskaya,
• Nurettin Menges and
• Metin Balci

Beilstein J. Org. Chem. 2015, 11, 897–905, doi:10.3762/bjoc.11.101

• reaction time, high yield, and easy isolation of the product 7 (entries 1 and 2, Table 1). We next investigated the isomerization of the double bond in 7, which was treated with trifluoroacetic acid (TFA) in chloroform at room temperature to give 3-methyl-1H-pyrrolo[2,1-c][1,4]oxazin-1-one (6) [27]. After

Discrete multiporphyrin pseudorotaxane assemblies from di- and tetravalent porphyrin building blocks

• Mirko Lohse,
• Larissa K. S. von Krbek,
• Sebastian Radunz,
• Suresh Moorthy,
• Christoph A. Schalley and
• Stefan Hecht

Beilstein J. Org. Chem. 2015, 11, 748–762, doi:10.3762/bjoc.11.85

• . After deprotection of the termini of the attached axles with trifluoroacetic acid (TFA), protonation of the free amines with HCl, and anion exchange with sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate (NaBArF), the target compounds A2 and A4 were obtained. The weakly coordinating BArF counter-ion

Multivalent polyglycerol supported imidazolidin-4-one organocatalysts for enantioselective Friedel–Crafts alkylations

• Tommaso Pecchioli,
• Manoj Kumar Muthyala,
• Rainer Haag and
• Mathias Christmann

Beilstein J. Org. Chem. 2015, 11, 730–738, doi:10.3762/bjoc.11.83

• . Therefore, a constant number of catalytic units for each degree of functionalization was maintained. Initially, we decided to perform the reaction using trans-cinnamaldehyde (12) as a model substrate and trifluoroacetic acid (TFA) as an additive. In a preliminary survey on the water influence, a catalyst

Self-assembly of heteroleptic dinuclear metallosupramolecular kites from multivalent ligands via social self-sorting

• Christian Benkhäuser and
• Arne Lützen

Beilstein J. Org. Chem. 2015, 11, 693–700, doi:10.3762/bjoc.11.79

• (3, 1 g, 5.1 mmol) and paraformaldehyde (323 mg, 10.8 mmol, 2.1 equiv) were mixed in a round-bottomed flask in the dark and cooled with an ice bath. Trifluoroacetic acid (15.2 mL, 133.2 mmol, 26 equiv) was added and the resulting mixture was stirred for 18 h in the dark. After that time the reaction

Synthesis of tripodal catecholates and their immobilization on zinc oxide nanoparticles

• Franziska Klitsche,
• Julian Ramcke,
• Julia Migenda,
• Andreas Hensel,
• Tobias Vossmeyer,
• Horst Weller,
• Silvia Gross and
• Wolfgang Maison

Beilstein J. Org. Chem. 2015, 11, 678–686, doi:10.3762/bjoc.11.77

• = hydroxybenzotriazole; TFA = trifluoroacetic acid, KOTMS = potassium trimethylsilanolate, DIEA = N,N-diisopropylethylamine. Synthesis of tripodal catecholate platforms 11 and 13 for surface functionalization. Supporting Information Supporting Information File 192: Experimental procedures, additional analytical data