Total synthesis and cytotoxicity of the marine natural product malevamide D and a photoreactive analog

• Werner Telle,
• Gerhard Kelter,
• Heinz-Herbert Fiebig,
• Peter G. Jones and
• Thomas Lindel

Beilstein J. Org. Chem. 2014, 10, 316–322, doi:10.3762/bjoc.10.29

• liberated the free acid 12, which was coupled with the trifluoroacetate of dolaproine ester 13, liberated from the N-Boc-protected analog [2]. With the subsequent coupling step affording TBDPS-protected malevamide D (14), we initially had difficulties. It proved to be crucial to remove excess of TFA from

Synthesis of nucleotide–amino acid conjugates designed for photo-CIDNP experiments by a phosphotriester approach

• Tatyana V. Abramova,
• Olga B. Morozova,
• Vladimir N. Silnikov and
• Alexandra V. Yurkovskaya

Beilstein J. Org. Chem. 2013, 9, 2898–2909, doi:10.3762/bjoc.9.326

• ) and L-tryptophanol (13). i) N,N’-Dicyclohexylcarbodiimide (DCC), N-hydroxysuccinimide (NHS), 1,4-dioxane, then 2(2-aminoethoxy)ethanol); ii) 2(2-aminoethoxy)ethanol), triethylamine (TEA), 1,4-dioxane; iii) p-chlorophenyl dichlorophosphate, 1,2,4-triazole, pyridine (Py); iv) ethyl trifluoroacetate, TEA

Recent advances in transition metal-catalyzed Csp²-monofluoro-, difluoro-, perfluoromethylation and trifluoromethylthiolation

• Grégory Landelle,
• Armen Panossian,
• Sergiy Pazenok,
• Jean-Pierre Vors and
• Frédéric R. Leroux

Beilstein J. Org. Chem. 2013, 9, 2476–2536, doi:10.3762/bjoc.9.287

• trifluoroacetic acid as the source of CF3− [80]. Ag2O was chosen as an additive to promote the decarboxylation, and to accelerate the reductive elimination step by precipitation of AgI. To circumvent the use of moisture-sensitive sodium trifluoroacetate, M. Beller et al. employed a combination of methyl

• trifluoroacetate (MTFA) and cesium fluoride to generate the trifluoroacetate anion which decarboxylated under the reaction conditions (Figure 5). In most cases, the system does not necessitate the use of amine ligands excepted when aryl bromides are used instead of aryl iodides [81]. Aryl and heteroaryl products

Synthetic scope and DFT analysis of the chiral binap–gold(I) complex-catalyzed 1,3-dipolar cycloaddition of azlactones with alkenes

• María Martín-Rodríguez,
• Luis M. Castelló,
• Carmen Nájera,
• José M. Sansano,
• Olatz Larrañaga,
• Abel de Cózar and
• Fernando P. Cossío

Beilstein J. Org. Chem. 2013, 9, 2422–2433, doi:10.3762/bjoc.9.280

• ) complexes 3 and 4, identified and characterized by Puddephatt’s group [X = trifluoroacetate (TFA)] [29][30][31], were obtained from NaAuCl4 and dimethyl sulfide and the corresponding amount of the chiral Binap ligand. Finally, the anion interchange was promoted by the addition of an equivalent amount of

A one-pot synthesis of 3-trifluoromethyl-2-isoxazolines from trifluoromethyl aldoxime

• Raoni S. B. Gonçalves,
• Michael Dos Santos,
• Guillaume Bernadat,
• Danièle Bonnet-Delpon and
• Benoit Crousse

Beilstein J. Org. Chem. 2013, 9, 2387–2394, doi:10.3762/bjoc.9.275

• available reagents have been employed under metal-free conditions. A group [27] reported that the hypervalent iodine reagents (diacetoxyiodo)benzene (DIB) and phenyliodine bis(trifluoroacetate) (PIFA) could successfully promote the oxidation of aldoximes to the corresponding nitrile oxide. Those reagents

Structure of 1,5-benzodiazepinones in the solid state and in solution: Effect of the fluorination in the six-membered ring

• Marta Pérez-Torralba,
• Rosa M. Claramunt,
• M. Ángeles García,
• Concepción López,
• M. Carmen Torralba,
• M. Rosario Torres,
• Ibon Alkorta and
• José Elguero

Beilstein J. Org. Chem. 2013, 9, 2156–2167, doi:10.3762/bjoc.9.253

• trifluoroacetate sample and then the chemical shifts were recalculated to the CFCl3 [δ (CF3COONH4+)] = –72.0 ppm) The six 1,5-benzodiazepinones discussed in this paper together with clobazam. The X-ray structures of 3a (TUPSAZ), 5a (EFARUA). In TUPSAZ there is a disordered water molecule. ORTEP plot (30

Practical synthesis of indoles and benzofurans in water using a heterogeneous bimetallic catalyst

• Cybille Rossy,
• Eric Fouquet and
• François-Xavier Felpin

Beilstein J. Org. Chem. 2013, 9, 1426–1431, doi:10.3762/bjoc.9.160

• was obtained when a trifluoroacetate function was used as protecting group, albeit in modest yield. The loss of the trifluoroacetate group likely occurred during the workup process. It should be noted that unprotected aniline exclusively led to the uncyclized Sonogashira adduct. Surprisingly a much

Establishing the concept of aza-[3 + 3] annulations using enones as a key expansion of this unified strategy in alkaloid synthesis

• Aleksey I. Gerasyuto,
• Zhi-Xiong Ma,
• Grant S. Buchanan and
• Richard P. Hsung

Beilstein J. Org. Chem. 2013, 9, 1170–1178, doi:10.3762/bjoc.9.131

• ] annulation reaction is described here. Use of piperidinium trifluoroacetate salt as the catalyst and toluene as the solvent appears to be critical for a successful annulation. We also demonstrated for the first time that microwave irradiation can accelerate aza-[3 + 3] annulation reactions. An attempt to

• intermediate 1b. We were elated to observe that the use of 100 mol % of piperidinium CSA salt in toluene at 120 °C provided 100% conversion with 60% yield of cycloadduct 11 (Table 1, entry 4). Further optimizations using trifluoroacetate salt (Table 1, entries 5–8) revealed that the yield could be improved to

• trifluoroacetate and camphorsulfonic acid salts, as compared to the chloride and acetate salts, can be attributed to the rate at which they promote vinyl iminium ion formation through a “balanced act” [12]. The difference in reactivity is related to the dissociation capacity of the respective amine salts. Since

Study on the total synthesis of velbanamine: Chemoselective dioxygenation of alkenes with PIFA via a stop-and-flow strategy

• Huili Liu,
• Kuan Zheng,
• Xiang Lu,
• Xiaoxia Wang and
• Ran Hong

Beilstein J. Org. Chem. 2013, 9, 983–990, doi:10.3762/bjoc.9.113

• Recently, Tellitu, Dominguez, and co-workers reported an intramolecular oxyamidation of alkene 11 with phenyliodine(III)-bis(trifluoroacetate) (PIFA) (Scheme 3) [46]. The lactam 12 was originally assigned as an unstable intermediate, which should be subsequently reduced to pyrrolidine 13. It was

• 11 with phenyliodine(III)-bis(trifluoroacetate) (PIFA) by Tellitu, Dominguez and co-workers [46]. Copper-catalyzed amination of aryliodide. Revised PIFA-promoted cyclization of amide 11. PIFA-promoted cyclization to synthesize lactone. “Stop-and-flow” strategy for the stepwise dioxygenation of

Synthesis of trifunctional cyclo-β-tripeptide templates

• Frank Stein,
• Tahir Mehmood,
• Tilman Plass,
• Javid H. Zaidi and
• Ulf Diederichsen

Beilstein J. Org. Chem. 2012, 8, 1576–1583, doi:10.3762/bjoc.8.180

• purification. DC (EtOAc/n-pentane 2:3 + 1% AcOH): Rf = 0.73. (S)-7-Azido-3-(tert-butoxycarbonylamino)heptanoic acid (3). A solution of silver trifluoroacetate (219 mg, 990 µmol, 0.110 equiv) in triethylamine (3.79 mL, 27.0 mmol, 3.00 equiv) was slowly added to a solution of (S)-tert-butyl 7-azido-1-diazo-2

Binaphthyl-anchored antibacterial tripeptide derivatives with hydrophobic C-terminal amino acid variations

• John B. Bremner,
• Paul A. Keller,
• Stephen G. Pyne,
• Mark J. Robertson,
• K. Sakthivel,
• Kittiya Somphol,
• Dean Baylis,
• Jonathan A. Coates,
• John Deadman,
• Dharshini Jeevarajah and
• David I. Rhodes

Beilstein J. Org. Chem. 2012, 8, 1265–1270, doi:10.3762/bjoc.8.142

• achieved by exposure to trifluoroacetic acid, followed by trifluoroacetate/chloride ion exchange on treatment with an excess of HCl in diethyl ether, and finally evaporation to afford the salts 2a–g in good overall yields. The structures of the final compounds were supported by 1H and 13C NMR spectroscopy

Chiral gold(I) vs chiral silver complexes as catalysts for the enantioselective synthesis of the second generation GSK-hepatitis C virus inhibitor

• María Martín-Rodríguez,
• Carmen Nájera,
• José M. Sansano,
• Abel de Cózar and
• Fernando P. Cossío

Beilstein J. Org. Chem. 2011, 7, 988–996, doi:10.3762/bjoc.7.111

• chiral ligand (Ra,R)-8 the enantioselectivities were low or moderate in the examples concerning AgClO4 and AgTFA (TFA = trifluoroacetate anion), respectively (Table 1, entries 5 and 7). Surprisingly, the reaction involving this chiral ligand 8 combined with AgSbF6 afforded a good yield of the

An overview of the key routes to the best selling 5-membered ring heterocyclic pharmaceuticals

• Marcus Baumann,
• Ian R. Baxendale,
• Steven V. Ley and
• Nikzad Nikbin

Beilstein J. Org. Chem. 2011, 7, 442–495, doi:10.3762/bjoc.7.57

• reaction conditions and gave rise to numerous by-products. An improved route was developed for the compounds large scale manufacture. The refined process route (Scheme 56) starts with a sequential bis-acylation of hydrazine with ethyl trifluoroacetate and chloroacetyl chloride [85]. The resulting hydrazide

Formation of epoxide-amine oligo-adducts as OH-functionalized initiators for the ring-opening polymerization of ε-caprolactone

• Julia Theis and
• Helmut Ritter

Beilstein J. Org. Chem. 2010, 6, 938–944, doi:10.3762/bjoc.6.105

• a pulsed nitrogen laser (25 Hz, 337 nm) were accelerated to 25 kV, the molecular masses being recorded in linear mode. Dithranol was used as a matrix and sodium trifluoroacetate (NaTFA) as ionization reagent. The samples were dissolved in THF. Molecular weights and molecular weight distributions

En route to photoaffinity labeling of the bacterial lectin FimH

• Thisbe K. Lindhorst,
• Michaela Märten,
• Andreas Fuchs and
• Stefan D. Knight

Beilstein J. Org. Chem. 2010, 6, 810–822, doi:10.3762/bjoc.6.91

• -aminoethyl mannoside 6 (Scheme 1) [23]. This led to the orthogonally protected mannoside amino acid tert-butyl esters 7 and 8. The tert-butyl ester groups were then cleaved under acidic conditions and the resulting acids ligated with the biotin derivative biotinylamidopropylammonium trifluoroacetate. These

• concentrated under reduced pressure. The resulting crude product was combined with HATU (150 mg, 0.43 mmol), (+)-biotinylamidopropylammonium trifluoroacetate (170 mg, 0.41 mmol) and dried for 30 min under vacuum. DMF (5 mL) and DIPEA (350 μL, 2.63 mmol) were then added under a nitrogen atmosphere. The reaction

• , 0.28 mmol) and (+)-biotinylamidopropylammonium trifluoroacetate (109 mg, 0.26 mmol), and dried for 30 min under vacuum. DMF (4 mL) and DIPEA (220 μL, 1.65 mmol) were then added under a nitrogen atmosphere. The reaction mixture was stirred overnight at RT, the solvent removed in vacuo and the residue

Synthesis and crossover reaction of TEMPO containing block copolymer via ROMP

• Olubummo Adekunle,
• Susanne Tanner and
• Wolfgang H. Binder

Beilstein J. Org. Chem. 2010, 6, No. 59, doi:10.3762/bjoc.6.59

• solution) in a ratio of 100:10:1. Dithranol (1,8-dihydroxy-9(10H)-anthracetone, Aldrich 97%) was used as the matrix. Sodium trifluoroacetate (Aldrich, 98%), silver trifluoroacetate (Aldrich, 99.99%) or lithium trifluoroacetate (Aldrich, 99.8%) were added for ion formation, with sodium trifluoroacetate as

Synthesis of glycosylated β³-homo-threonine conjugates for mucin-like glycopeptide antigen analogues

• Florian Karch and
• Anja Hoffmann-Röder

Beilstein J. Org. Chem. 2010, 6, No. 47, doi:10.3762/bjoc.6.47

• was cooled to 0 °C. A solution of 0.11 equiv silver trifluoroacetate in 2.3 equiv NMM was added, and the mixture was stirred for 16 h while it was allowed to warm to room temperature. After evaporation of THF, the aqueous layer was diluted with saturated aqueous NaHCO3 and Et2O was added. The organic

Pd-catalyzed decarboxylative Heck vinylation of 2-nitrobenzoates in the presence of CuF₂

• Lukas J. Gooßen,
• Bettina Zimmermann and
• Thomas Knauber

Beilstein J. Org. Chem. 2010, 6, No. 43, doi:10.3762/bjoc.6.43

• trifluoroacetate and by 5 mol % silver salts yielding 2,6-dimethoxybenzene in 75% and 99% yield, respectively. This finding further supports our theory that the catalyst cycle outlined by Myers for electron-rich benzoic acids, in which silver(I) acts as only an oxidant and is not involved in the decarboxylation

Symmetrical and unsymmetrical α,ω-nucleobase amide-conjugated systems

• Sławomir Boncel,
• Maciej Mączka,
• Krzysztof K. K. Koziol,
• Radosław Motyka and
• Krzysztof Z. Walczak

Beilstein J. Org. Chem. 2010, 6, No. 34, doi:10.3762/bjoc.6.34

• -dioxo-3,4-dihydropyrimidin-1(2H)-yl]tetrahydro-furan-2-yl}methoxy)-4-oxobutanoic acid (1g) [22]. The amine subunits employed were 3-[5-nitro-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl]propan-1-aminium trifluoroacetate (2g) [23], 6-[5-nitro-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl]hexan-1-aminium

• trifluoroacetate (2h) [23] and 1-[(2R,4S,5R)-5-(aminomethyl)-4-hydroxytetrahydrofuran-2-yl]-5-methylpyrimidine-2,4-(1H,3H)-dione (2l) [24]. The synthesis of the amine subunit 2j was carried out according to the known procedure [25]. The unprotected hydroxyl group in sugar moieties, as expected, was entirely

Self-association of an indole based guanidinium-carboxylate-zwitterion: formation of stable dimers in solution and the solid state

• Carolin Rether,
• Wilhelm Sicking,
• Roland Boese and
• Carsten Schmuck

Beilstein J. Org. Chem. 2010, 6, No. 3, doi:10.3762/bjoc.6.3

• -guanidinium trifluoroacetate (7): Trifluoroacetic acid (3 mL) was added to the ethyl 7-[N,N’-bis-(tert-butoxycarbonyl)guanidino]-1H-indole-2-carboxylate (6, 170 mg, 0.39 mmol), and the reaction mixture was stirred at room temperature for 2 h. The excess trifluoroacetic acid was removed in vacuo to give 7 as a

• , 161.1; IR (KBr): ν = 3298 (w), 3193 (w), 3101 (w), 2955 (w), 1699 (m), 1671 (s), 1255 (s) cm−1; HR-MS (ESI) calcd for [M+H]+: 247.1190; found 247.1215. 7-Guanidinio-1H-indole-2-carboxylate (2): To a solution of the trifluoroacetate salt 7 (130 mg, 0.53 mmol) in water/THF (1/4; 15 mL) LiOH·H2O (223 mg

Recent progress on the total synthesis of acetogenins from Annonaceae

• Nianguang Li,
• Zhihao Shi,
• Yuping Tang,
• Jianwei Chen and
• Xiang Li

Beilstein J. Org. Chem. 2008, 4, No. 48, doi:10.3762/bjoc.4.48

• . The iodide 266 was coupled with the higher-order vinylcyanocuprate to afford olefin 267, which could be converted to the epoxide 268. Addition of (R)-lithio-2-(OTBS)-3-butyne afforded the trifluoroacetate 269, then 269 was converted into the butenolide 270. Cleavage of the SEM protecting group

The first preparative solution phase synthesis of melanotan II

• Vladimir V. Ryakhovsky,
• Georgy A. Khachiyan,
• Nina F. Kosovova,
• Elena F. Isamiddinova and
• Andrey S. Ivanov

Beilstein J. Org. Chem. 2008, 4, No. 39, doi:10.3762/bjoc.4.39

• the guanidine group in arginine, it was deactivated as the monohydrochloride salt over the course of 4 steps, and then as trifluoroacetate for another 2 steps. A similar method for arginine deactivation had been applied earlier in the first solution-phase synthesis of ACTH [30]. The assembly of the

• all acid-labile groups with excess of trifluoroacetic acid (TFA) yielded the tris-trifluoroacetate salt of deprotected linear hexapeptide 11 with all prerequisites for cyclization. The cyclization step, involving the ε-amino group of lysine and γ-carboxy group of aspartic acid, was performed using an

Synthesis of deep- cavity fluorous calix[4]arenes as molecular recognition scaffolds

• Maksim Osipov,
• Qianli Chu,
• Steven J. Geib,
• Dennis P. Curran and
• Stephen G. Weber

Beilstein J. Org. Chem. 2008, 4, No. 36, doi:10.3762/bjoc.4.36

• . Correspondingly, 3b was treated with silver trifluoroacetate [32] in the presence of iodine providing iodide 5 in 72% yield on a 1 mmol scale (Scheme 2). Results for the iodination were scale dependent; near quantitative yields could be obtained on 0.1 mmol scale preparations, while 1 mmol scale preparations

Diels- Alder reactions using 4,7-dioxygenated indanones as dienophiles for regioselective construction of oxygenated 2,3-dihydrobenz[f]indenone skeleton

• Natsuno Etomi,
• Takuya Kumamoto,
• Waka Nakanishi and
• Tsutomu Ishikawa

Beilstein J. Org. Chem. 2008, 4, No. 15, doi:10.3762/bjoc.4.15

• indanetrione 8, but attempts with bromoindanone 18 resulted in no reaction even under reflux. Utilization of a milder oxidant phenyliodosyl bis(trifluoroacetate) (PIFA) [33] for the oxidation of phenolic indanone 20, derived from 18 by selective demethylation with magnesium iodide (MgI2) [34], gave

Transition- metal/Lewis acid free synthesis of acyl benzothiophenes via C-C bond forming reaction

• Sarbani Pal,
• Mohammad Ashrafuddin Khan,
• P. Bindu and
• P. K. Dubey

Beilstein J. Org. Chem. 2007, 3, No. 35, doi:10.1186/1860-5397-3-35

• acid plays a role of covalent catalyst which leads to the generation of acyl bis(trifluoroacetyl)phosphate from the acylation precursor acyl trifluoroacetate generated in situ.[33] The acyl bis(trifluoroacetyl)phosphate then acetylates the benzothiophene ring in the presence of phosphoric acid to