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

The chemistry of isoindole natural products

• Klaus Speck and
• Thomas Magauer

Beilstein J. Org. Chem. 2013, 9, 2048–2078, doi:10.3762/bjoc.9.243

• in the total synthesis of 193 by Schmalz (Scheme 24) [149]. Reaction of lithiated 188 (three steps from commercially available 5-methylresorcinol) with the aldehyde 189 (double bromination of 3,5-dimethoxybenzaldehyde) gave the racemic alcohol 190. Oxidation to the benzophenone, installation of the

• for a more labile methoxymethyl ether at the benzophenone stage. The following prenylation and formylation proceeded smoothly under the same conditions to give 191b (Scheme 24). Cleavage of the MOM ethers afforded pestalone (192), which could be converted into 193 in a single step by treatment of 192

Total synthesis of (−)-epimyrtine by a gold-catalyzed hydroamination approach

• Thi Thanh Huyen Trinh,
• Khanh Hung Nguyen,
• Patricia de Aguiar Amaral and
• Nicolas Gouault

Beilstein J. Org. Chem. 2013, 9, 2042–2047, doi:10.3762/bjoc.9.242

• high quality were purchased from commercial suppliers and used without further purification. All reactions requiring anhydrous conditions were performed under an argon atmosphere by using oven-dried glassware. 1,2-DCE and THF were distilled from CaH2 and Na/benzophenone, respectively. 1H and 13C NMR

The application of a monolithic triphenylphosphine reagent for conducting Ramirez gem-dibromoolefination reactions in flow

• Kimberley A. Roper,
• Malcolm B. Berry and
• Steven V. Ley

Beilstein J. Org. Chem. 2013, 9, 1781–1790, doi:10.3762/bjoc.9.207

• withdrawing groups [47]. A selection of these ketones were therefore subjected to the flow Ramirez reaction conditions (Table 2). Unsurprisingly, unactivated ketones such as cyclohexanone and benzophenone gave no conversion to the desired dibromide using the standard conditions. However, with some

Electron self-exchange activation parameters of diethyl sulfide and tetrahydrothiophene

• Martin Goez and
• Martin Vogtherr

Beilstein J. Org. Chem. 2013, 9, 1448–1454, doi:10.3762/bjoc.9.164

• spin mixing becomes effective [30]. All these conditions are fulfilled by the 2,4,6-triphenylpyrylium cation TTP+. Compared to typical carbonyl sensitizers such as benzophenone or xanthone, its reduction potential (−0.29 V in acetonitrile versus SCE [31]) is more favorable by more than 2 V, yet its

Copper(II)-salt-promoted oxidative ring-opening reactions of bicyclic cyclopropanol derivatives via radical pathways

• Eietsu Hasegawa,
• Minami Tateyama,
• Ryosuke Nagumo,
• Eiji Tayama and
• Hajime Iwamoto

Beilstein J. Org. Chem. 2013, 9, 1397–1406, doi:10.3762/bjoc.9.156

• distilled with K2CO3. CH2Cl2 was treated with H2SO4, water, 5% NaOH, water, and CaCl2, and then distilled with CaH2. THF was distilled over sodium benzophenone under N2. Anhydrous DMF was purchased and used without distillation. Other reagents and solvents were purchased and used without further

Copper-catalyzed aerobic aliphatic C–H oxygenation with hydroperoxides

• Pei Chui Too,
• Ya Lin Tnay and
• Shunsuke Chiba

Beilstein J. Org. Chem. 2013, 9, 1217–1225, doi:10.3762/bjoc.9.138

• 3% yields, respectively, via the desired 1,4-dioxygenation, while benzophenone (7b) was also formed in 30% yield through fragmentation of the transient alkoxy radical (Scheme 4). Use of 40 mol % of NHPI slightly improved the yields of 1,4-dioxygenation products 2i and 3i (40% and 4% yields

Design and synthesis of tag-free photoprobes for the identification of the molecular target for CCG-1423, a novel inhibitor of the Rho/MKL1/SRF signaling pathway

• Jessica L. Bell,
• Andrew J. Haak,
• Susan M. Wade,
• Yihan Sun,
• Richard R. Neubig and
• Scott D. Larsen

Beilstein J. Org. Chem. 2013, 9, 966–973, doi:10.3762/bjoc.9.111

• high-resolution mass-spectral analysis. We selected benzophenone and azide as the PGs for incorporation into 2 based on synthetic ease and their complementary photoreactivities (benzophenone inserts into C–H bonds, azide into heteroatom–H bonds) [12]. Furthermore, we had previously established that

• benzophenone is tolerated on the benzamide ring with retention of the biological activity (3, Table 1) [23]. In addition to a PG, we needed a suitable linking functionality for attachment of a clickable acetylene group. Preliminary work (data not shown) established that an ether (versus amide) linker was

• superior with regard to maintenance of biological activity. A small set of model compounds was thus prepared to evaluate the impact of ether linker and PG placement on biological activity (see below in Table 1). Scheme 1 depicts the general synthesis of model benzophenone-probes 8. Boc-protected nipecotic

New core-pyrene π structure organophotocatalysts usable as highly efficient photoinitiators

• Sofia Telitel,
• Frédéric Dumur,
• Thomas Faury,
• Bernadette Graff,
• Mohamad-Ali Tehfe,
• Didier Gigmes,
• Jean-Pierre Fouassier and
• Jacques Lalevée

Beilstein J. Org. Chem. 2013, 9, 877–890, doi:10.3762/bjoc.9.101

• architectures (Scheme 2) [42][43][44] are linked PI–PI units (e.g., PI = pyrene) or PI-PI’ (e.g., PI = pyrene and PI’ = 2,2’-dimethoxy-2-phenylacetophenone) and PI moieties (e.g., PI = benzophenone, thioxanthone, 2,2’-dimethoxy-2-phenylacetophenone, pyrene) linked to a trifunctional core (truxene, triazine

Preparation and ring-opening reactions of N-diphenylphosphinyl vinyl aziridines

• Ashley N. Jarvis,
• Andrew B. McLaren,
• Helen M. I. Osborn and
• Joseph Sweeney

Beilstein J. Org. Chem. 2013, 9, 852–859, doi:10.3762/bjoc.9.98

• procedures. Light petroleum refers to the fraction boiling in the range 40 to 60 °C. Diethyl ether, THF and DME were distilled from sodium benzophenone ketyl; toluene from sodium; dichloromethane, triethylamine, diisopropylamine and acetonitrile from calcium hydride; and pyridine and diisopropylethylamine

Synthesis and stability study of a new major metabolite of γ-hydroxybutyric acid

• Ida Nymann Petersen,
• Jesper Langgaard Kristensen,
• Christian Tortzen,
• Torben Breindahl and
• Daniel Sejer Pedersen

Beilstein J. Org. Chem. 2013, 9, 641–646, doi:10.3762/bjoc.9.72

• , glassware was dried overnight in an oven at 150 °C and was allowed to cool in a desiccator over anhydrous KOH. Anhydrous reactions were carried out under nitrogen. THF was distilled from sodium wire with benzophenone as indicator. Dichloromethane and pyridine were dried and stored over 4 Å molecular sieves

Efficient synthesis of β’-amino-α,β-unsaturated ketones

• Isabelle Abrunhosa-Thomas,
• Aurélie Plas,
• Nishanth Kandepedu,
• Pierre Chalard and
• Yves Troin

Beilstein J. Org. Chem. 2013, 9, 486–495, doi:10.3762/bjoc.9.52

• synthetic method to the preparation of piperidine natural products. Experimental Organic solutions were dried over MgSO4 or Na2SO4, and filtered. When anhydrous solvents were used, they were prepared as follows: tetrahydrofuran (THF) was distilled under N2 from sodium benzophenone ketyl and used immediately

Electron and hydrogen self-exchange of free radicals of sterically hindered tertiary aliphatic amines investigated by photo-CIDNP

• Martin Goez,
• Isabell Frisch and
• Ingo Sartorius

Beilstein J. Org. Chem. 2013, 9, 437–446, doi:10.3762/bjoc.9.46

• anthraquinone (AQ) and xanthone (XA) or benzophenone (BP) were investigated by time-resolved photo-CIDNP (photochemically induced dynamic nuclear polarization) experiments. By varying the radical-pair concentration, it was ensured that these measurements respond only to self-exchange reactions of the free amine

• ) and triisopropylamine (TIPA). The hindrance is due to a stereoelectronic effect with DABCO [21], and due to overcrowding with TIPA [22]. As sensitizers, we have chosen 9,10-anthraquinone (AQ) on one hand and xanthone (XA) or benzophenone (BP) on the other; with triethylamine, these are typical

• -resolved CIDNP in sensitized (sensitizers xanthone (XA), benzophenone (BP), or anthraquinone (AQ)) photoreactions of 1,4-diazabicyclo[2.2.2]octane (DABCO). Shown are the relative CIDNP intensities (integrals) Irel (DABCO) of the 12 equivalent amine protons (s, 2.64 ppm) as functions of the delay t between

De novo synthesis of D- and L-fucosamine containing disaccharides

• Daniele Leonori and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2013, 9, 332–341, doi:10.3762/bjoc.9.38

• Ar atmosphere by using standard Schlenk techniques. THF and Et2O were distilled from purple Na/benzophenone diketyl; CH2Cl2, pyridine and BF3·Et2O were distilled from CaH2. Deionized water was obtained from an in-house purification system. The compounds purified by flash chromatography were further

Asymmetric synthesis of γ-chloro-α,β-diamino- and β,γ-aziridino-α-aminoacylpyrrolidines and -piperidines via stereoselective Mannich-type additions of N-(diphenylmethylene)glycinamides across α-chloro-N-sulfinylimines

• Gert Callebaut,
• Sven Mangelinckx,
• Pieter Van der Veken,
• Karl W. Törnroos,
• Koen Augustyns and
• Norbert De Kimpe

Beilstein J. Org. Chem. 2012, 8, 2124–2131, doi:10.3762/bjoc.8.239

• mixture. Unfortunately, all attempted purification techniques (column chromatography, preparative TLC, acid-base extraction) to remove benzophenone and some other minor impurities from the crude reaction mixture, failed to provide the pure N-deprotected syn-β,γ-aziridino-α-aminocarboxylamide 9b

• a benzophenone imine functionality, in the presence of an N-p-toluenesulfinyl moiety, of diamino esters with H3PO4/H2O/THF [17][40]. In a subsequent step, syn-γ-chloro-α,β-diaminocarboxylamide 10b was chemoselectively cyclized to the corresponding N-sulfinyl-β,γ-aziridino-α-aminocarboxylamide 11b

• hydrolysis of the benzophenone imine functionality proceeds readily and prevents the formation of the corresponding trans-imidazolidine. Conclusion In conclusion, it was demonstrated that new chiral syn-γ-chloro-α,β-diaminocarboxylamides are formed in acceptable to good yields and with excellent