Design and synthesis of fused polycycles via Diels–Alder reaction and ring-rearrangement metathesis as key steps

• Sambasivarao Kotha and
• Ongolu Ravikumar

Beilstein J. Org. Chem. 2015, 11, 1259–1264, doi:10.3762/bjoc.11.140

• -sensitive reagents or catalysts were performed in degassed solvents. Dry tetrahydrofuran (THF) and dry ether were obtained by distillation over sodium benzophenone ketyl freshly prior to use. Dichloromethane (DCM) and toluene were distilled over P2O5 and DMF over CaH2. Sodium sulfate was dried in an oven at

Interactions between tetrathiafulvalene units in dimeric structures – the influence of cyclic cores

• Huixin Jiang,
• Virginia Mazzanti,
• Christian R. Parker,
• Søren Lindbæk Broman,
• Jens Heide Wallberg,
• Karol Lušpai,
• Adam Brincko,
• Henrik G. Kjaergaard,
• Anders Kadziola,
• Peter Rapta,
• Ole Hammerich and
• Mogens Brøndsted Nielsen

Beilstein J. Org. Chem. 2015, 11, 930–948, doi:10.3762/bjoc.11.104

• -radiaannulenes exhibit low-energy CT absorptions. Experimental General Methods – Synthesis. Chemicals were purchased from Aldrich, Fluka, and GSF Chemicals and used as received. THF was distilled over the Na/benzophenone couple. Solvents were of HPLC grade and used as received. Thin layer chromatography (TLC

Probing multivalency in ligand–receptor-mediated adhesion of soft, biomimetic interfaces

• Stephan Schmidt,
• Hanqing Wang,
• Daniel Pussak,
• Simone Mosca and
• Laura Hartmann

Beilstein J. Org. Chem. 2015, 11, 720–729, doi:10.3762/bjoc.11.82

• -functionalized SCPs. Carboxy groups on the SCP were introduced by a radical grafting process where incubation of the PEG microgels with benzophenone and acrylic acid lead to poly(acrylic acid) grafts on the PEG backbone. Using this model system, we could already show that the mechanical flexibility of the

• (Scheme 1). It is known that benzophenone can absorb the energy of photons to excite the electron in its carbonyl group from ground state (S0) to the excited state (S1) or (S2) depending on the wavelength used. Subsequently, the excited electron can go to the triple state (T1) through intersystem crossing

• (ISC). At the T1 state, the benzophenone molecule has an excited electron which is highly reactive, and can abstract a hydrogen atom from the PEG backbone. The abstracted hydrogen atom generates a radical on the PEG-backbone and a semipinacol radical on the benzophenone carbonyl group [16]. In the

Trifluoromethyl-substituted tetrathiafulvalenes

• Olivier Jeannin,
• Frédéric Barrière and
• Marc Fourmigué

Beilstein J. Org. Chem. 2015, 11, 647–658, doi:10.3762/bjoc.11.73

• from Na/benzophenone. CH3CN and CH2Cl2 were distilled over P2O5 and MeOH over Mg/I2. Column chromatography was performed on silica gel. 1H, 13C and 19F NMR spectra were obtained on a Bruker Avance DRX500 spectrometer at 500.04 MHz for 1H, 470.28 MHz for 19F and 125.75 MHz for 13C. Chemical shifts were

Photocatalytic nucleophilic addition of alcohols to styrenes in Markovnikov and anti-Markovnikov orientation

• Martin Weiser,
• Sergej Hermann,
• Alexander Penner and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2015, 11, 568–575, doi:10.3762/bjoc.11.62

• °C, using a 250 mW high-power LED (λ = 530 nm) as light source while stirring. Preliminary experiments with substrate 1 revealed that formation of benzophenone was nearly completely prevented by carefully degassing the reaction mixture. A previous report of Neunteufel and Arnold considered the

Attempts to prepare an all-carbon indigoid system

• Şeref Yildizhan,
• Henning Hopf and
• Peter G. Jones

Beilstein J. Org. Chem. 2015, 11, 363–372, doi:10.3762/bjoc.11.42

• direct conjugation, whereby a third such system is excluded from interaction [3]. Typical examples are 2-vinyl-buta-1,3-diene ([3]dendralene, 3-methylene-penta-1,4-diene), benzophenone or urea. Whereas the hydrocarbon parent systems, the [n]dendralenes, have long been a neglected class of oligoenes [4

An unusually stable chlorophosphite: What makes BIFOP–Cl so robust against hydrolysis?

• Roberto Blanco Trillo,
• Jörg M. Neudörfl and
• Bernd Goldfuss

Beilstein J. Org. Chem. 2015, 11, 313–322, doi:10.3762/bjoc.11.36

• application as a chiral ligand to be used in, for example, Pd catalysis [13][14][15]. Experimental All reactions were carried out under an inert argon atmosphere and in heated glassware using standard Schlenk techniques. Anhydrous solvents were obtained by distillation from sodium benzophenone ketyl. The NMR

(2R,1'S,2'R)- and (2S,1'S,2'R)-3-[2-Mono(di,tri)fluoromethylcyclopropyl]alanines and their incorporation into hormaomycin analogues

• Armin de Meijere,
• Sergei I. Kozhushkov,
• Dmitrii S. Yufit,
• Christian Grosse,
• Marcel Kaiser and
• Vitaly A. Raev

Beilstein J. Org. Chem. 2014, 10, 2844–2857, doi:10.3762/bjoc.10.302

• -threonine (4) and (2S,3R)-β-methylphenylalanine (3), using the Belokon' approach with (S)- and (R)-2-[(N-benzylprolyl)amino]benzophenone [(S)- and (R)-10] as reusable chiral auxiliaries have been developed. Three new fluoromethyl analogues of the naturally occurring octadepsipeptide hormaomycin (1) with

• from (S)- and (R)-2-[(N-benzylprolyl)amino]benzophenone [(S)- and (R)-10] as reusable chiral auxiliaries with the racemic iodides 11a–c, employing the protocol of Larionov and de Meijere [7], in each case led to a mixture of diastereomeric products, which were separated by column chromatography

• corresponding (2S,1'S,2'R)- [see Scheme 3, derived from (S)-10] and (2R,1'S,2'R)-3-(2'-fluoromethylcyclopropyl)alanines [derived from (R)-10] in good to excellent yields. The chiral auxiliary was recovered as the hydrochloride of 2-[(N-benzylprolyl)amino]benzophenone (~95%). (R)-allo-Threonine (4) is

Design and synthesis of novel bis-annulated caged polycycles via ring-closing metathesis: pushpakenediol

• Sambasivarao Kotha and
• Mirtunjay Kumar Dipak

Beilstein J. Org. Chem. 2014, 10, 2664–2670, doi:10.3762/bjoc.10.280

• nitrogen by using oven-dried glassware and syringes. THF and Et2O were distilled from sodium/benzophenone under nitrogen immediately prior to use. Dichloromethane was distilled over P2O5. TLC was performed by using (10 × 5 cm) glass plates coated with Acme’s silica gel GF254 (containing 13% calcium sulfate

Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids

• Roman Matthessen,
• Jan Fransaer,
• Koen Binnemans and
• Dirk E. De Vos

Beilstein J. Org. Chem. 2014, 10, 2484–2500, doi:10.3762/bjoc.10.260

• was first described by Wawzonek, converting benzophenone and acetophenone to benzylic acid and 2-hydroxy-2-phenylpropionic acid, respectively [79]. This offers an electrochemical route for several commercially relevant α-aryl propionic acids, used as non-steroidal anti-inflammatory drugs (NSAIDs) [80

Scalable synthesis of 5,11-diethynylated indeno[1,2-b]fluorene-6,12-diones and exploration of their solid state packing

• Bradley D. Rose,
• Peter J. Santa Maria,
• Aaron G. Fix,
• Chris L. Vonnegut,
• Lev N. Zakharov,
• Sean R. Parkin and
• Michael M. Haley

Beilstein J. Org. Chem. 2014, 10, 2122–2130, doi:10.3762/bjoc.10.219

• the UV–vis spectrum (Table 3). To see if this was a computational artifact, the same calculations were performed for fluorenone and benzophenone, where it has previously been established that the S0→S1 transition corresponds to π→π* and n→π*, respectively [29][30]. The calculations correctly predict

• the ordering of the states for fluorenone and benzophenone. To validate this experimentally, UV–vis spectra were gathered in solvents of differing polarity. We anticipated that if the S0→S1 transition corresponds to a n→π* transition, the energy separating the S0 and S1 states would be measurably

Photorelease of phosphates: Mild methods for protecting phosphate derivatives

• Sanjeewa N. Senadheera,
• Abraham L. Yousef and
• Richard S. Givens

Beilstein J. Org. Chem. 2014, 10, 2038–2054, doi:10.3762/bjoc.10.212

• triplet sensitized photolysis in the presence of benzophenone (BP), a well-established triplet sensitizer, at 254 nm under O2-free conditions was Φdis = 0.022. These combined results demonstrate that the reactive excited state is a triplet that is partially quenched by O2 under ambient conditions

• disappearance quantum efficiency (Table 2). 4. Triplet sensitization experiment. A quartz tube was charged with 14a (2.0 mg, 0.0059 mmol) and benzophenone (20 mg, 0.11 mmol), and the contents were dissolved in acetonitrile (10 mL) to which was added water (100 µL) to make a 1% aqueous solution. The solution was

• degassed with argon and irradiated with 6-RPR 2540 Å bulbs. Sample aliquots (0.2 mL) were taken after 0, 2, 5, 7, and 10 min of photolysis and analyzed by HPLC on a C18 analytical column with a mobile phase containing 70% acetonitrile and 30% water. The detection wavelength was 323 nm. The benzophenone had

An economical and safe procedure to synthesize 2-hydroxy-4-pentynoic acid: A precursor towards ‘clickable’ biodegradable polylactide

• Quanxuan Zhang,
• Hong Ren and
• Gregory L. Baker

Beilstein J. Org. Chem. 2014, 10, 1365–1371, doi:10.3762/bjoc.10.139

• methods All reactions, if not stated otherwise, were performed in oven-dried glassware under nitrogen atmosphere. THF and dioxane were dried over sodium/benzophenone and distilled before use. All other reagents and solvents were ACS grade and used as received unless specified. Melting points were measured

Homochiral BINOL-based macrocycles with π-electron-rich, electron-withdrawing or extended spacing units as receptors for C₆₀

• Marco Caricato,
• Silvia Díez González,
• Idoia Arandia Ariño and
• Dario Pasini

Beilstein J. Org. Chem. 2014, 10, 1308–1316, doi:10.3762/bjoc.10.132

• ], 3a [28], 4a [28] and p-toluenesulfonic acid 4-dimethylaminopyridinium salt (PTSA-DMAP) [45] were prepared according to literature procedures. THF (Na, benzophenone) and CH2Cl2 (CaH2) were dried before use. Analytical thin-layer chromatography was performed on silica gel, chromophore loaded, and with

Homogeneous and heterogeneous photoredox-catalyzed hydroxymethylation of ketones and keto esters: catalyst screening, chemoselectivity and dilution effects

• Axel G. Griesbeck and
• Melissa Reckenthäler

Beilstein J. Org. Chem. 2014, 10, 1143–1150, doi:10.3762/bjoc.10.114

• cyclic ketones as substrates (Scheme 3). Even benzophenone, a notorious pinacol forming substrate, gave moderate yields of the hydroxymethylation product 7. Among the aromatic ketones, para-fluoroacetophenone was the most reactive ketone. Excellent yields were obtained for 2-pentanone where the product

Visible-light-induced, Ir-catalyzed reactions of N-methyl-N-((trimethylsilyl)methyl)aniline with cyclic α,β-unsaturated carbonyl compounds

• Dominik Lenhart and
• Thorsten Bach

Beilstein J. Org. Chem. 2014, 10, 890–896, doi:10.3762/bjoc.10.86

• tricyclic product 4 employing 4,4’-bis(dimethylamino)benzophenone (3) as the catalyst [38]. In this case, the amine was used in large excess (15 equiv) and the chiral menthyl group was derived from (−)-menthol. It was later found that the reaction proceeds with a higher yield (73%) if acetone was employed

Addition of H-phosphonates to quinine-derived carbonyl compounds. An unexpected C9 phosphonate–phosphate rearrangement and tandem intramolecular piperidine elimination

• Łukasz Górecki,
• Artur Mucha and
• Paweł Kafarski

Beilstein J. Org. Chem. 2014, 10, 883–889, doi:10.3762/bjoc.10.85

• chromatography, for details see Supporting Information File 1). C9 position modification, phosphonate–phosphate rearrangement Oxidation of the C9 hydroxy group of quinine to the corresponding ketone, quininone, was performed with potassium tert-butoxide and benzophenone (Scheme 4) [34]. Using toluene as the

Zirconoarylation of alkynes through p-chloranil-promoted reductive elimination of arylzirconates

• Xiaoyu Yan,
• Chao Chen and
• Chanjuan Xi

Beilstein J. Org. Chem. 2014, 10, 528–534, doi:10.3762/bjoc.10.48

• commercially available and were used without further purification. Tetrahydrofuran (THF) was refluxed and freshly distilled from dark purple solutions of sodium and benzophenone under nitrogen atmosphere. 1H NMR and 13C NMR spectra were recorded on 300 MHz and 400 MHz NMR spectrometers with TMS as internal

Synthesis and stereochemical assignments of diastereomeric Ni(II) complexes of glycine Schiff base with (R)-2-(N-{2-[N-alkyl-N-(1-phenylethyl)amino]acetyl}amino)benzophenone; a case of configurationally stable stereogenic nitrogen

• Hiroki Moriwaki,
• Daniel Resch,
• Hengguang Li,
• Iwao Ojima,
• Ryosuke Takeda,
• José Luis Aceña and
• Vadim A. Soloshonok

Beilstein J. Org. Chem. 2014, 10, 442–448, doi:10.3762/bjoc.10.41

• its (SCRN) absolute configuration. Accordingly, the second product, diastereomer 6b, has (SCSN) configuration. The X-ray structure of 5b revealed the complex is not fully planar as expected. The benzophenone chelate ring system deviates from planarity by 14.4° (0.16 e.s.d.). The torsion angle of Ni2

• –O5–C10–C29 is −10.9° further indicating a deviation from planarity. One of the rings in the benzophenone chelate is rotated 85.8° (0.36 e.s.d.) out of the plane presumably due to sterics. This rotation minimizes the Ar–H···H–Ar repulsion as well as repulsion with methylene group of the glycine moiety

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

• 200 times less active than the natural product 1. Lower cytotoxicity may be associated with solubility problems. We will now search for more water-soluble, photoactivatable analogs of 1. Nunes and coworkers had synthesized a benzophenone-labelled derivative of the analog HTI-286, which competes with 3

Substrate dependent reaction channels of the Wolff–Kishner reduction reaction: A theoretical study

• Shinichi Yamabe,
• Guixiang Zeng,
• Wei Guan and
• Shigeyoshi Sakaki

Beilstein J. Org. Chem. 2014, 10, 259–270, doi:10.3762/bjoc.10.21

• (Ph)2 in 85% yield from benzophenone hydrazone Ph2C=N–NH2 and potassium tert-butoxide KOt-Bu in DMSO [10]. Grundon et al. obtained the product also in 85% yield in toluene [11]. These non-aqueous experimental results indicate that the tert-butoxide ion directly participates in the proton shifts. As a

• (OCH2CH2)2OH [9]. Reactions from the benzophenone hydrazone to the diphenylmethane in aprotic solvents such DMSO [10] and toluene [11] are discussed. Even if proton sources are absent, paths similar to VIIIph (hydrazone) → IXPh(TS4) → XPh → XIPh(TS5) → XIIPh (diimine) → XIIIPh(TS6) →XIVPh (carbanion) may

A unified approach to the important protein kinase inhibitor balanol and a proposed analogue

• Tapan Saha,
• Ratnava Maitra and
• Shital K. Chattopadhyay

Beilstein J. Org. Chem. 2013, 9, 2910–2915, doi:10.3762/bjoc.9.327

• natural product. Based on the information [48][49] that balanol binds to the ATP-docking site of protein kinase, all the three distinct domains present in the natural product such as the benzophenone core [50][51][52], the azepine core [53][54][55][56][57][58][59] and the p-hydroxybenzamide [60][61] unit

• unified precursor of balanol (1) and an azepin ring-modified balanol 3. Derivative 4 could be obtained through esterification between the carboxylic acid 5 and the allylic alcohol 6. We thus focused on the synthesis of the two key fragments 5 and 6. The synthesis of the benzophenone unit has previously

• effected a smooth conversion to the new benzylic alcohol 10. The latter was oxidized with tetrapropylammonium perruthenate to provide the benzophenone derivative 11 in good yield. Subsequent cleavage of the 1,3-dioxane unit followed by oxidation of the resulting aldehyde 12 furnished carboxylic acid 13 in

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

• , SB RAS, Institutskaya 3a, Novosibirsk 630090, Russia 10.3762/bjoc.9.326 Abstract Conjugates of 2’-deoxyguanosine, L-tryptophan and benzophenone designed to study pathways of fast radical reactions by the photo Chemically Induced Dynamic Nuclear Polarization (photo-CIDNP) method were obtained by the

• experiments, has a disadvantage of a relatively low absorbance at a wavelength of 308 nm at physiological pH. As an alternative, in our investigations water soluble carboxylic derivatives of benzophenone (namely, 4-carboxy-, 3-carboxy- and 3,3’,4,4’-tetracarboxybenzophenone) were used as efficient

One-pot cross-enyne metathesis (CEYM)–Diels–Alder reaction of gem-difluoropropargylic alkynes

• Santos Fustero,
• Paula Bello,
• Javier Miró,
• María Sánchez-Roselló,
• Günter Haufe and
• Carlos del Pozo

Beilstein J. Org. Chem. 2013, 9, 2688–2695, doi:10.3762/bjoc.9.305

• purified prior to use: THF, diethyl ether and toluene were distilled from sodium/benzophenone; dichloromethane and acetonitrile were distilled from calcium hydride. The reactions were monitored with the aid of thin-layer chromatography (TLC) on 0.25 mm precoated silica gel plates. Visualization was carried

Towards stereochemical control: A short formal enantioselective total synthesis of pumiliotoxins 251D and 237A

• Jie Zhang,
• Hong-Kui Zhang and
• Pei-Qiang Huang

Beilstein J. Org. Chem. 2013, 9, 2358–2366, doi:10.3762/bjoc.9.271

• (THF) was distilled prior to use from sodium benzophenone ketyl. Dichloromethane was distilled from phosphorus pentoxide. Silica gel (zhifu, 300–400 mesh) from Yantai silica gel factory (China) was used for column chromatography, eluting (unless otherwise stated) with ethyl acetate/petroleum ether (PE