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

Crystal engineering of analogous and homologous organic compounds: hydrogen bonding patterns in trimethoprim hydrogen phthalate and trimethoprim hydrogen adipate

• Packianathan Thomas Muthiah,
• Savarimuthu Francis,
• Urszula Rychlewska and
• Beata Warżajtis

Beilstein J. Org. Chem. 2006, 2, No. 8, doi:10.1186/1860-5397-2-8

• dihydrate [12], TMP-trifluoroacetate [15], TMP-formate [16], TMP-hydrogen glutarate [17], TMP-nitrate [18], TMP-salicylate methanol solvate [19] etc,. In the crystal structures of TMP-terephthalate-terephthalic acid [13], TMP-3-carboxy-4-hydroxybenzenesulfonate dihydrate [14] and TMP-sulfate trihydrate [20

• structures of trimethoprim-salicylate methanol solvate [18], trimethoprim-trifluoroacetate [15], pyrimethamine-hydrogen phthalate [21] etc,. The characteristic hydrogen-bonded rings observed in the structure aggregate into a supramolecular ladder consisting of a pair of chains, each of which is built up of