Block copolymers from ionic liquids for the preparation of thin carbonaceous shells

• Sadaf Hanif,
• Bernd Oschmann,
• Dmitri Spetter,
• Muhammad Nawaz Tahir,
• Wolfgang Tremel and
• Rudolf Zentel

Beilstein J. Org. Chem. 2017, 13, 1693–1701, doi:10.3762/bjoc.13.163

• -transform infrared (FTIR) spectroscopy was conducted on a Jasco FT/IR 4100 spectrometer with an attenuated total reflectance (ATR) unit. The SEC measurements were carried out at 40 °C with a solution of HFIP with 3 g L−1 K+TFA− as eluent. Modified silica was used as stationary phase and a refractive index

• ), 4.51 (br, polymer backbone), 2.91 (m, polymer backbone), 2.80 (s, CH2-CH2 of NAS), 1.23 (m, CTA dodecyl chain), 0.85 (t, dodecyl-CH3 of CTA); FTIR ν: 2969 (w), 2255 (w), 1808 (m), 1732 (s, C=O, reactive ester), 1553 (s), 1204 (m), 1161 cm−1 (m); SEC (eluent: HFIP): 23 098 g mol−1, PDI = 1.17. Synthesis

• , CTA dodecyl chain), 0.85 (t, dodecyl-CH3 of CTA); FTIR ν: 2969 (w), 2255 (w), 1691 (m), 1645 (m, C=O, amide of dopamine), 1553 (s), 1434 (m), 1160 (m), 1020 cm−1 (m); SEC (eluent: HFIP): 23 180 g mol−1, PDI = 1.22. Synthesis of in situ functionalized TiO2 nanoparticles: 400 mg of catechol containing

A strategic approach to [6,6]-bicyclic lactones: application towards the CD fragment of DHβE

• Tue Heesgaard Jepsen,
• Emil Glibstrup,
• François Crestey,
• Anders A. Jensen and
• Jesper Langgaard Kristensen

Beilstein J. Org. Chem. 2017, 13, 988–994, doi:10.3762/bjoc.13.98

• reaction by applying basic (K2CO3, LiOH) and acidic (TFA, BF3) conditions but unfortunately this caused complete decomposition of the starting material upon heating. However, the cyclization was successful by heating 25 at 80 °C in the slightly acidic hexafluoro-2-propanol (HFIP). HFIP seemed exactly

• acidic enough to mediate the reaction without causing decomposition. Although 25 was fully converted into a single product the targeted compound 26 proved to be extremely difficult to isolate and purify. The compound as the free amine was very volatile and co-evaporated with different solvents (HFIP

• or AcOH. xii) Pd(OH)2, H2, EtOAc or MeOH or AcOH. Second strategy towards the CD fragment. i) 4-Bromobut-1-ene, K2CO3, acetone, 70 °C. ii) n-BuLi, THF, −78 °C, 1 h, then ClCO2Et, −78 °C, 1 h. iii) LiI, AcOH, 50 °C. iv) PdCl2(PPh3)2, Ag2CO3, THF, 50 °C. v) LiOH, H2O, THF, rt. vi) HFIP, 80 °C

Transition-metal-catalyzed synthesis of phenols and aryl thiols

• Yajun Liu,
• Shasha Liu and
• Yan Xiao

Beilstein J. Org. Chem. 2017, 13, 589–611, doi:10.3762/bjoc.13.58

• hydroxylated oxime could be readily converted to o-acylphenol or o-aminomethylphenol. In 2016, Sunoj and co-workers disclosed the first meta-hydroxylation of arenes using a tethered -CN directing group [68]. The conversion proceeded at 70 °C in hexafluoro-2-propanol (HFIP) in the presence of Pd(OAc)2, PhI(TFA

• investigation revealed that HFIP participated in the catalytic cycle before the activation of C–H bond. 1.2.2.2 Carboxylic acid, ketone and their derivatives as directing groups: In 2009, the Yu group used Pd(OAc)2 and accomplished the direct ortho-hydroxylation of benzoic acid [69]. Their developed protocol

cis-Diastereoselective synthesis of chroman-fused tetralins as B-ring-modified analogues of brazilin

• Dimpee Gogoi,
• Runjun Devi,
• Pallab Pahari,
• Bipul Sarma and
• Sajal Kumar Das

Beilstein J. Org. Chem. 2016, 12, 2816–2822, doi:10.3762/bjoc.12.280

• using 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) as reaction medium as well as the reaction promoter. The first choice of HFIP was based on its recently found ability to promote high-yielding IFCEA cyclization of benzylic epoxides [29]. Unfortunately, however, refluxing a solution of (±)-6a in HFIP for 4

• h (entry 1, Table 1) led to the formation of a mixture of two major isolable compounds, out of which one was the expected product (±)-5 (50%) and the remaining one was hexafluoroisopropyl ether (generated from the nucleophilic addition of HFIP on the benzylic position). Meanwhile, we found that

Inhibition of peptide aggregation by means of enzymatic phosphorylation

• Kristin Folmert,
• Malgorzata Broncel,
• Hans v. Berlepsch,
• Christopher H. Ullrich,
• Mary-Ann Siegert and
• Beate Koksch

Beilstein J. Org. Chem. 2016, 12, 2462–2470, doi:10.3762/bjoc.12.240

• of phosphorylation, time-dependent CD (circular dichroism) measurements were performed. To ensure comparable and reproducible starting conditions, a disaggregation and concentration validation assay using HFIP (1,1,1,3,3,3-hexafluoropropan-2-ol) was performed. Thus, all aggregates that may have

• of the phosphate group towards soluble random structures, chemically phosphorylated PCKFM6 was synthesized for control experiments. The peptide was dissolved in HFIP stock solution, as was unphosphorylated KFM6. For CD experiments PCKFM6 was prepared in two-fold higher concentration (30 µM) compared

• by dissolving the purified, Abz labeled peptide in HFIP (≈1 mg mL−1) and sonicating for 15 minutes to dissolve all aggregates. 50 µL of this solution were aliquoted and dried under nitrogen flow, before the residue was dissolved in 1 mL 50 mM Tris/HCl buffer containing 10 mM MgCl2 at pH 7.5. UV

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

• Bin Yu,
• Hui Xing,
• De-Quan Yu and
• Hong-Min Liu

Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98

• situ, giving the corresponding products with 93–99% ee. This modified protocol was also extended to electron-rich heteroarene substrates. Interestingly, hexafluoroisopropanol (HFIP) was found to be able to improve the enantioselectivity significantly. The authors also proposed a possible transition

Synthesis of novel N-cyclopentenyl-lactams using the Aubé reaction

• Madhuri V. Shinde,
• Rohini S. Ople,
• Ekta Sangtani,
• Rajesh Gonnade and
• D. Srinivasa Reddy

Beilstein J. Org. Chem. 2015, 11, 1060–1067, doi:10.3762/bjoc.11.119

• use of hexafluoroisopropanol (HFIP) can reduce the Lewis acid requirement. Accordingly, by varying a few conditions, we were able to optimize the reaction as summarized in Table 1. The optimized conditions are: 2.5 equiv of ketone, 4–5 equiv of HFIP and one equiv of BF3·OEt2 followed by hydrolysis

• ·OEt2 Boron trifluoride etherate (0.07 mL, 0.71 mmol) was added to a solution of azido alcohol 3 (0.10 g, 0.71 mmol) and ketones (2.0 mmol, 3 equiv) in HFIP (0.2 mL) cooled to 0 °C. The mixture was warmed to room temperature and stirred for 2–5 h. Upon completion, the reaction was quenched with 15% aq

Recent advances in the electrochemical construction of heterocycles

• Robert Francke

Beilstein J. Org. Chem. 2014, 10, 2858–2873, doi:10.3762/bjoc.10.303

• product distribution. Under aprotic conditions, the formation of 13 is favored, whereas in presence of HFIP (1,1,1,3,3,3-hexafluoroisopropanol) as a proton donor, product 14 is formed exclusively. On the basis of faradaic yields, cyclic voltammetry data and product distribution, the authors proposed the

Synthesis of rigid p-terphenyl-linked carbohydrate mimetics

• Maja Kandziora and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2014, 10, 1749–1758, doi:10.3762/bjoc.10.182

• -coupling of compound 16. Conditions: Pd(PPh3)2Cl2, 2 M Na2CO3, DMF, 80 °C, 3 d. Hydrogenolysis of compound 27 and samarium diiodide-mediated reaction leading to compounds 30 and 31. Conditions: a) H2, Pd/C, TFA, HFIP, iPrOH, 8 h, rt; b) SmI2 (0.1 M in THF), MeOH, 30 min, rt. HFIP = hexafluoro-2-propanol

Synthesis of the first examples of iminosugar clusters based on cyclopeptoid cores

• Mathieu L. Lepage,
• Alessandra Meli,
• Anne Bodlenner,
• Céline Tarnus,
• Francesco De Riccardis,
• Irene Izzo and
• Philippe Compain

Beilstein J. Org. Chem. 2014, 10, 1406–1412, doi:10.3762/bjoc.10.144

• ’-diisopropylcarbodiimide (DIC)-mediated acylation with bromoacetic acid, followed by amination with the propargyl amine. After the completion of synthesis, the oligomers were cleaved from the resin using a 4:1 solution of CH2Cl2/hexafluoroisopropanol (HFIP). Macrocyclizations of the linear N-substituted oligoglycines 6–8

• -yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate. (a) bromoacetic acid, DIPEA, CH2Cl2; (b) propargylamine (10 equiv), DMF; (c) bromoacetic acid, DIC, DMF; (d) CH2Cl2/HFIP (4:1); (e) HATU, DIPEA, DMF. Synthesis of DNJ clusters 10: (a) CuSO4·5H2O cat., sodium ascorbate, DMF/H2O (5:1), MW, 80 °C; (b

Synthesis of ethoxy dibenzooxaphosphorin oxides through palladium-catalyzed C(sp²)–H activation/C–O formation

• Seohyun Shin,
• Dongjin Kang,
• Woo Hyung Jeon and
• Phil Ho Lee

Beilstein J. Org. Chem. 2014, 10, 1220–1227, doi:10.3762/bjoc.10.120

• , HFIP, THF, toluene, TFA and MeOH (see Supporting Information File 1). With this preliminary result in hand, we investigated a variety of organic acids as ligands in an effort to improve the catalytic efficiency (Scheme 3). However, these attempts provided no improvement (Table 1, entries 2–4). Finally

Synthesis of five- and six-membered cyclic organic peroxides: Key transformations into peroxide ring-retaining products

• Alexander O. Terent'ev,
• Dmitry A. Borisov,
• Vera A. Vil’ and
• Valery M. Dembitsky

Beilstein J. Org. Chem. 2014, 10, 34–114, doi:10.3762/bjoc.10.6

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

• (Table 1, entry 1). This is probably due to the nucleophilic addition of methanol to the highly electrophilic trifluoroacetonitrile oxide. The utilization of the less nucleophilic alcohol hexafluoroisopropanol (HFIP) [33][34] led to the formation of a complex mixture (Table 1, entry 2). The oxidation of

• Marie Curie program, the Farmaguinhos/FioCruz, and PGQu for financial support. Central Glass Co. Ltd. is gratefully acknowledged for kindly providing fluoral hydrate and HFIP, as well as the IT department from Université Paris-Sud for providing computing resources. The authors would like thank M’bokeno

Peptoids and polyamines going sweet: Modular synthesis of glycosylated peptoids and polyamines using click chemistry

• Daniel Fürniss,
• Timo Mack,
• Frank Hahn,
• Sidonie B. L. Vollrath,
• Katarzyna Koroniak,
• Ute Schepers and
• Stefan Bräse

Beilstein J. Org. Chem. 2013, 9, 56–63, doi:10.3762/bjoc.9.7

• both resins, the peptoid synthesis was successful; the only differences are the functional groups on the C-terminus. After cleavage from Rink-amide resin with trifluoroacetic acid, an amide is obtained, whereas cleavage from 2-chlorotrityl chloride resin with hexafluoroisopropanol (HFIP) gives the

• by treatment with 33% hexafluoroisopropanol (HFIP) in dichloromethane and subsequent HPLC purification resulted in the fully glycosylated hexameric product 28 (Scheme 4). Conclusion In conclusion, we were able to improve protocols for the synthesis of tetra-O-acetyl protected sugars. Applying this

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

• peptide was cleaved from the resin using a 30% solution of HFIP in DCM (5.00 mL) for 45 min. Afterwards, the cleavage cocktail was filtered, the resin was washed (3 × 3 mL 30% HFIP in DCM) and all phases combined. The excess solvent was removed under a nitrogen stream and the crude product was

Synthesis of szentiamide, a depsipeptide from entomopathogenic Xenorhabdus szentirmaii with activity against Plasmodium falciparum

• Friederike I. Nollmann,
• Andrea Dowling,
• Marcel Kaiser,
• Klaus Deckmann,
• Sabine Grösch,
• Richard ffrench-Constant and
• Helge B. Bode

Beilstein J. Org. Chem. 2012, 8, 528–533, doi:10.3762/bjoc.8.60

• % hexafluoroisopropanol (HFIP) in dichloromethane (DCM) in order to preserve the side-chain protecting group. Following this, the peptide was cyclized in solution by using O-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate (HATU) and DIEA in DMF, assisted by microwave irradiation. Afterwards, the

• was cleaved with 3% hexafluoroisopropanol (HFIP; Carbolution Chemicals, Germany) in dichloromethane (DCM; VWR, Germany) and cyclized in solution (20 min, 25 W; 75 °C) by using O-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate (HATU; Carbolution Chemicals, Germany) and DIEA in

Kinetic evaluation of the solvolysis of isobutyl chloro- and chlorothioformate esters

• Malcolm J. D’Souza,
• Matthew J. McAneny,
• Dennis N. Kevill,
• Jin Burm Kyong and
• Song Hee Choi

Beilstein J. Org. Chem. 2011, 7, 543–552, doi:10.3762/bjoc.7.62

• chloroformate (neoPenOCOCl) [14] solvolyzes in the HFIP rich mixtures with a Wagner–Meerwein 1,2-methyl shift leading to the formation of a tertiary pentyl cation. In 13 of the more nucleophilic solvents the l/m ratio of 3.67 (Table 3) for neoPenOCOCl was found to be typical of a bimolecular AN + DN process [14

• type of alkyl group present. In Table 5, for solvolysis in the least nucleophilic and most highly ionizing solvent, 97% HFIP (w/w), a rate order of kMeSCOCl << kEtSCOCl < kiBuSCOCl << kiPrSCOCl is observed. This demonstrates that the hyperconjugative release during the formation of the developing

Chromo- and fluorophoric water-soluble polymers and silica particles by nucleophilic substitution reaction of poly(vinyl amine)

• Katja Hofmann,
• Ingolf Kahle,
• Frank Simon and
• Stefan Spange

Beilstein J. Org. Chem. 2010, 6, No. 79, doi:10.3762/bjoc.6.79

• both compounds, the shortest UV–vis absorption maxima were observed at λmax(1-M) = 568 nm and λmax(1-P) = 513 nm in HFIP. 1-M shows the longest wavelength UV–vis absorption band at λmax = 580 nm in DMSO, whereas 1-P has the strongest bathochromic shift in ethanol at λmax = 538 nm. These band shifts

• the longest-wavelength emission maximum in DMSO at λmax = 595 nm and 1-P in ethanol at λmax = 586 nm. The longest hypsochromic shifts of the fluorescence emission maximum were observed at λmax(1-M) = 577 nm in HFIP and λmax(1-P) = 561 nm in DMMA. These band shifts correspond to a small solvatochromic

• range of Δ(1-M) = 524 cm−1 and Δ(1-P) = 760 cm−1, respectively. Furthermore, for 1-M only a small Stokes shift (9–15 nm) is observed, whereas 1-P shows a larger one (26–63 nm), which reaches a maximum in strong HBD solvents (HFIP). Again, the solvent-dependent fluorescence emission maxima can be