Chiral Cu(II)-catalyzed enantioselective β-borylation of α,β-unsaturated nitriles in water

• Lei Zhu,
• Taku Kitanosono,
• Pengyu Xu and
• Shū Kobayashi

Beilstein J. Org. Chem. 2015, 11, 2007–2011, doi:10.3762/bjoc.11.217

• Lei Zhu Taku Kitanosono Pengyu Xu Shu Kobayashi Department of Chemistry, School of Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, Japan 10.3762/bjoc.11.217 Abstract The promising performance of copper(II) complexes was demonstrated for asymmetric boron conjugate addition to α,β

• substrates were suitable despite being insoluble in water. Keywords: carbon–boron bond formation; catalytic asymmetric synthesis; chiral copper(II) catalysis; β-hydroxy nitriles; Introduction In recent years, optically active organoboranes have attracted considerable attraction as versatile synthons for

Synthesis of constrained analogues of tryptophan

• Elisabetta Rossi,
• Valentina Pirovano,
• Marco Negrato,
• Giorgio Abbiati and
• Monica Dell’Acqua

Beilstein J. Org. Chem. 2015, 11, 1997–2006, doi:10.3762/bjoc.11.216

• only using copper(II) triflate as catalyst (Table 1, entry 5). Unsatisfactory results were obtained also in the presence of gold(III) and gold(I) catalysts (Table 1, entries 8 and 9). Only in the presence of a cationic gold(I) complex the diastereoisomeric cycloadducts 3a and 3'a were isolated in 20

Effective ascorbate-free and photolatent click reactions in water using a photoreducible copper(II)-ethylenediamine precatalyst

• Redouane Beniazza,
• Natalia Bayo,
• Florian Molton,
• Carole Duboc,
• Stéphane Massip,
• Nathan McClenaghan,
• Dominique Lastécouères and
• Jean-Marc Vincent

Beilstein J. Org. Chem. 2015, 11, 1950–1959, doi:10.3762/bjoc.11.211

• water in the absence of sodium ascorbate is an active area of current research with strong potential for applications in bioconjugation. The water-soluble and photoreducible copper(II)–EDA (EDA = ethylenediamine) complex 1, which has two 4-benzoylbenzoates acting as both counterion and photosensitizer

• Gautier and coworkers based on a water-soluble Cu(I)–NHC complex, which could be used under ascorbate-free and open air conditions for the CuAAC ligation of oxidation-sensitive peptides in buffered aqueous media [10]. Recently, we developed the photoreducible copper(II) complexes 2 and 3 incorporating a

• organic solvents, typically MeOH, THF or toluene. It should be noted that within the last four years, other photoreducible copper(II)-based catalytic systems applied to click chemistry have been reported [15][16][17][18][19][20][21][22][23][24][25][26][27], in particular for the preparation of polymers

The facile construction of the phthalazin-1(2H)-one scaffold via copper-mediated C–H(sp²)/C–H(sp) coupling under mild conditions

• Wei Zhu,
• Bao Wang,
• Shengbin Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2015, 11, 1624–1631, doi:10.3762/bjoc.11.177

• combination of Cu(OAc)2 and Li2CO3 in DMF under an oxygen atmosphere (Table 1, entry 1). As shown in Table 1, various bases, copper(II) salts and solvents were screened for the best reaction conditions. With Cu(OAc)2 as the transition metal and DMF as the solvent at 90 °C under oxygen atmosphere, we tested

• recovered in good yield. Based on previous works [22][23][25], a copper(II)-mediated C–H functionalization pathway is proposed in Scheme 5. A base-promoted cupration of the relatively acidic C–H of ethynylbenzene provides ethynylcopper intermediate M1. The following bidentate chelation with 1a yields

Star-shaped tetrathiafulvalene oligomers towards the construction of conducting supramolecular assembly

• Masahiko Iyoda and
• Masashi Hasegawa

Beilstein J. Org. Chem. 2015, 11, 1596–1613, doi:10.3762/bjoc.11.175

• ]. Reflecting its strong π-donor ability, 1 was oxidized spontaneously in solution to afford 1•+ under ambient conditions. Multifunctional TTF-crown ether-substituted phthalocyanine (Pc) 2a and its copper(II) complex 2b were reported by Amabilino, Rowan, Nolte, and co-workers in 2005 [40]. The giant molecule 2a

Synthesis and spectroscopic properties of β-triazoloporphyrin–xanthone dyads

• Dileep Kumar Singh and
• Mahendra Nath

Beilstein J. Org. Chem. 2015, 11, 1434–1440, doi:10.3762/bjoc.11.155

• )-catalyzed Huisgen 1,3-dipolar cycloaddition reaction of copper(II) 2-azido-5,10,15,20-tetraphenylporphyrin or zinc(II) 2-azidomethyl-5,10,15,20-tetraphenylporphyrin with various alkyne derivatives of xanthones in DMF containing CuSO4 and ascorbic acid at 80 °C. Furthermore, these metalloporphyrins underwent

• ), 3-ethynyl-6-nitroxanthen-9-one (4), and 3-ethynyl-6-methoxyxanthen-9-one (5) were synthesized by using the literature procedures [39][40][47][48][49]. In addition, copper(II) 2-azido-5,10,15,20-tetraphenylporphyrin (1) [50] was synthesized in good yield after the treatment of copper(II) 2-amino

• and BF3·Et2O in 1,4-dioxane at 80 °C for 2 hours [51]. Initially, the copper(II) and zinc(II) derivatives of β-triazoloporphyrin–xanthone conjugates 6a,d,g and 7a,c were synthesized in 60–76% yields through a copper(I)-catalyzed Huisgen 1,3-dipolar cycloaddition reaction between copper(II) 2-azido

Synthesis of alpha-tetrasubstituted triazoles by copper-catalyzed silyl deprotection/azide cycloaddition

• Zachary L. Palchak,
• Paula T. Nguyen and
• Catharine H. Larsen

Beilstein J. Org. Chem. 2015, 11, 1425–1433, doi:10.3762/bjoc.11.154

• triazoles. A streamlined two-step approach to this uncommon class of hindered triazoles will accelerate exploration of their therapeutic potential. The superior activity of copper(II) triflate in the formation of triazoles from sensitive alkyne substrates extends to simple terminal alkynes. Keywords: azide

• was not stable in the presence of the copper(II) chloride catalyst, and triethylsilylacetylene did not convert cleanly to product. Triisopropylsilyl (TIPS) acetylene was found to be superior to tert-butyldimethylsilylacetylene as a source of silylated tetrasubstituted propargylic amines. Although TMS

• ) as well as copper(II) sources with an equal amount of sodium ascorbate as the reducing agent were tested in MeOH (Table 1, entries 6–14). All combinations of copper(II) salts with reductant provide higher GC yields (79–99%, Table 1, entries 9–14) than CuCl alone (65%, Table 1, entry 6) at 18 h

Intermolecular addition reactions of N-alkyl-N-chlorosulfonamides to unsaturated compounds

• Gerold Heuger and
• Richard Göttlich

Beilstein J. Org. Chem. 2015, 11, 1226–1234, doi:10.3762/bjoc.11.136

• using copper(I) chloride as the catalyst, which (after oxidation to copper(II) chloride) captures carbon radicals at a diffusion controlled rate [38]. Indeed using copper(I) chloride as the catalyst we obtained a yield of 60% of the addition product with sulfonamide 1a being the remaining side product

Design, synthesis and photochemical properties of the first examples of iminosugar clusters based on fluorescent cores

• Mathieu L. Lepage,
• Antoine Mirloup,
• Manon Ripoll,
• Fabien Stauffert,
• Anne Bodlenner,
• Raymond Ziessel and
• Philippe Compain

Beilstein J. Org. Chem. 2015, 11, 659–667, doi:10.3762/bjoc.11.74

• bearing a tetraethylene glycol chain tethered to the boron center via an ethynyl bond proved difficult. The use of copper(I) bromide dimethyl sulfide complex [63] at room temperature led to a complex mixture of products. Better results were obtained with copper(II) sulfate and sodium ascorbate under

Diastereoselective and enantioselective conjugate addition reactions utilizing α,β-unsaturated amides and lactams

• Katherine M. Byrd

Beilstein J. Org. Chem. 2015, 11, 530–562, doi:10.3762/bjoc.11.60

• group has developed several methods for Diels–Alder and aldol reactions that employed chiral bis(oxazoline) copper(II) complexes [180]. Starting in 1999, Evans and co-workers published a series of papers which reported the Mukaiyama–Michael addition to various α,β-unsaturated Michael acceptors [181][182

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

Sequential decarboxylative azide–alkyne cycloaddition and dehydrogenative coupling reactions: one-pot synthesis of polycyclic fused triazoles

• Kuppusamy Bharathimohan,
• Thanasekaran Ponpandian,
• A. Jafar Ahamed and
• Nattamai Bhuvanesh

Beilstein J. Org. Chem. 2014, 10, 3031–3037, doi:10.3762/bjoc.10.321

• methodology is more convenient to produce the complex polycyclic molecules in a simple way. Keywords: copper(II) acetate; decarboxylative CuAAC; dehydrogenative coupling; fused triazoles; one-pot synthesis; Introduction The copper-catalyzed Huisgen [3 + 2] cycloaddition (or copper-catalyzed azide–alkyne

(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

• ]. Although (R)-threonine is less expensive (21–37 € for 5 g) than the target amino acid, the conversion requires five steps, and the overall yield is not better than 72%. The Belokon' protocols are among the best to access enantiomerically pure non-proteogenic amino acids. Nickel(II) or copper(II) complexes

Host–guest-driven color change in water: influence of cyclodextrin on the structure of a copper complex of poly((4-hydroxy-3-(pyridin-3-yldiazenyl)phenethyl)methacrylamide-co-dimethylacrylamide)

• Nils Retzmann,
• Gero Maatz and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 2480–2483, doi:10.3762/bjoc.10.259

• experiments. Keywords: cyclodextrin; copolymer; copper(II) sulfate; supramolecular; water complex; Introduction In recent years, the interest in stimuli-responsive polymers increased exponentially [1]. Many polymers have been described, showing sensitivity towards e.g. light, pH and heat [2][3][4

• :50 vol % in methanol/water solution. UV–vis absorption spectra of (orange) the solved copolymer 7 with the induced shifts by addition of (red) copper(II) sulfate and (blue) γ-CD in an aqueous methanol medium. Number average particle size distribution of 7 obtained by DLS experiments. Synthesis of N

A small azide-modified thiazole-based reporter molecule for fluorescence and mass spectrometric detection

• Stefanie Wolfram,
• Hendryk Würfel,
• Stefanie H. Habenicht,
• Christine Lembke,
• Phillipp Richter,
• Eckhard Birckner,
• Rainer Beckert and
• Georg Pohnert

Beilstein J. Org. Chem. 2014, 10, 2470–2479, doi:10.3762/bjoc.10.258

• mM) of BPT (1) or the other reporter molecules (5 mM stock in DMSO), 9 µL (0.1 mM) TBTA solution (1.7 mM stock in DMSO/tert-butanol, 1:4, v/v) and 3 µL (20 mM) freshly prepared ascorbic acid solution (1.00 M in water). Samples were vortexed and 1 µL (1 mM) copper(II) sulfate solution (from a 50 mM

• (1.7 mM stock in DMSO/tert-butanol, 1:4, v/v) and 1 µL (20 mM) of a freshly prepared ascorbic acid solution (1.00 M in water). Samples were vortexed and 1 µL (1 mM) copper(II) sulfate solution (50 mM in water) was added. Samples were vortexed again and stored on ice for 1 hour. SDS-PAGE and in-gel

Exploration of C–H and N–H-bond functionalization towards 1-(1,2-diarylindol-3-yl)tetrahydroisoquinolines

• Michael Ghobrial,
• Marko D. Mihovilovic and
• Michael Schnürch

Beilstein J. Org. Chem. 2014, 10, 2186–2199, doi:10.3762/bjoc.10.226

• , as decomposition was observed due to partial cleavage of the Boc group. Addition of 1 equiv of copper(II) acetate facilitated the reaction and 51% of the desired product 6a were obtained (Table 2, entry 1). Further screening of reaction parameters (e.g., prolonged reaction time and other acids such

• applying copper or iron as the catalyst (Table 5). When performing the reaction under copper(II) nitrate catalysis, a good yield of 83% of 7a was obtained when 1-phenylindole (5a) was used as N-arylindole coupling partner (Table 5, entry 1). On the other hand, a significant decrease in product yield was

• purification of the final product extremely difficult. Hence, it was decided to change to another sequence instead of further optimizing this procedure. Converting 8 into 1 – final step of routes E and F Starting materials 8 were subjected to standard indolation conditions, using copper(II) nitrate as catalyst

Visible light photoredox-catalyzed deoxygenation of alcohols

• Daniel Rackl,
• Viktor Kais,
• Peter Kreitmeier and
• Oliver Reiser

Beilstein J. Org. Chem. 2014, 10, 2157–2165, doi:10.3762/bjoc.10.223

• acids (Supporting Information File 1) it was found that 6e could be selectively prepared by copper(II) chloride-catalyzed benzoylation of diol 8 with anhydride 9, which in turn can be generated from its acid 5 by treatment with acetic anhydride (Scheme 6). Since acetic anhydride is technically being

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

• -Bromination with copper(II) bromide [20] gave 8 (96%, direct bromination of 6 gave poor yields). The TBS group was removed in 30% aqueous methanol containing 10–20% methylene chloride and several molar equivalents of potassium hydrogen sulfate to provide hydroxy bromo ketone 9 (yield, 75%) [21], which was

• with Friedel–Crafts acylation of 1-methoxynaphthalene (11) yielding 1-acetyl-4-methoxynaphthalene (12, 73%). α-Bromination with copper(II) bromide gave 13 (44%) which was converted to the phosphate ester using tetramethylammonium diethyl phosphate in dimethoxyethane (DME) at room temperature to give

One-pot stereoselective synthesis of α,β-differentiated diamino esters via the sequence of aminochlorination, aziridination and intermolecular S_N2 reaction

• Yiwen Xiong,
• Ping Qian,
• Chenhui Cao,
• Haibo Mei,
• Jianlin Han,
• Guigen Li and
• Yi Pan

Beilstein J. Org. Chem. 2014, 10, 1802–1807, doi:10.3762/bjoc.10.189

• with α,β-unsaturated esters as starting materials. On the initial reaction step the cinnamic ester underwent a copper(II) trifluoromethanesulfonate-catalyzed aminohalogenation reaction with TsNCl2 as nitrogen source. After being quenched by saturated sodium sulfite, the resulting mixture was stirred

Multicomponent reactions in nucleoside chemistry

• Mariola Koszytkowska-Stawińska and
• Włodzimierz Buchowicz

Beilstein J. Org. Chem. 2014, 10, 1706–1732, doi:10.3762/bjoc.10.179

• clay or silica gel), the use of the CeCl3/NaI catalyst system for the synthesis of intermediates 113 provided the best results in terms of reaction yield and time. The next step leading to final products 114, i.e., the reductive dehydrazination of compounds 113 with alumina-supported copper(II) sulfate

On the mechanism of photocatalytic reactions with eosin Y

• Michal Majek,
• Fabiana Filace and
• Axel Jacobi von Wangelin

Beilstein J. Org. Chem. 2014, 10, 981–989, doi:10.3762/bjoc.10.97

• with arenediazonium salts are often more selective than traditional methods such as copper(II)-mediated Meerwein arylations [11] or protocols employing stoichiometric iron(II) or titanium(III) reductants in aqueous media [12][13][14]. This renaissance of arene diazonium chemistry has recently led to

Towards allosteric receptors – synthesis of β-cyclodextrin-functionalised 2,2’-bipyridines and their metal complexes

• Christopher Kremer,
• Gregor Schnakenburg and
• Arne Lützen

Beilstein J. Org. Chem. 2014, 10, 814–824, doi:10.3762/bjoc.10.77

• (I) ions as effectors. Copper(I) ions indeed form complexes very fast. However, the complexes of 1 and 3 are obviously prone to rapid oxidation to copper(II) species. These are paramagnetic complexes which cannot be analysed by NMR spectroscopy. Since this technique would be our preferred analytical

Polyglycerol-functionalized nanodiamond as a platform for gene delivery: Derivatization, characterization, and hybridization with DNA

• Li Zhao,
• Yuki Nakae,
• Hongmei Qin,
• Tadamasa Ito,
• Takahide Kimura,
• Hideto Kojima,
• Lawrence Chan and
• Naoki Komatsu

Beilstein J. Org. Chem. 2014, 10, 707–713, doi:10.3762/bjoc.10.64

• solution of ND-PG-N3 (10 mg) in water (2.0 mL). Copper(II) sulfate pentahydrate (8.0 mg) in water (0.5 mL) and sodium ascorbate (10 mg) in water (0.5 mL) were added into the mixture with vigorous stirring. The resulting brown suspension was bath-sonicated for 10 min and then stirred at room temperature for

• ) NaN3, 90 °C, overnight; iv) copper(II) sulfate pentahydrate, sodium ascorbate, rt, 96 h. Hydrodynamic diameter and zeta potential of nanoparticles in Milli-Q water. Acknowledgements This work was financially supported by the Science and Technology Incubation Program in Advanced Region (JST

Copper–phenanthroline catalysts for regioselective synthesis of pyrrolo[3′,4′:3,4]pyrrolo[1,2-a]furoquinolines/phenanthrolines and of pyrrolo[1,2-a]phenanthrolines under mild conditions

• Rupankar Paira,
• Tarique Anwar,
• Maitreyee Banerjee,
• Yogesh P. Bharitkar,
• Shyamal Mondal,
• Sandip Kundu,
• Abhijit Hazra,
• Prakas R. Maulik and
• Nirup B. Mondal

Beilstein J. Org. Chem. 2014, 10, 692–700, doi:10.3762/bjoc.10.62

• azomethine ylides, generated in situ from the parent furo[3,2-h]quinoliniums/phenanthroliums, in presence of a copper(II) chloride–phenanthroline catalytic system. The methodology combines general applicability with high yields. Keywords: copper(II) chloride–phenanthroline; 1,3-dipolar cycloaddition; furo

• after an extensive screening, we found copper(II) chloride–phenanthroline as the best catalytic pair for this purpose. Herein we wish to present the results of our recent synthetic efforts to synthesize a series of unique pentacyclic pyrrolo[3′,4′:3,4]pyrrolo[1,2-a]furoquinolines/phenanthrolines using

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

• copper(II) chloride under air (Scheme 27) [69]. However, with respect to the reaction reported in Scheme 26, also affording isoquinolines of general formula 48, a diverse arrangement of substituents can be achieved. The proposed reaction mechanism takes into account the recent applications of an oxygen