Copper-catalyzed stereoselective conjugate addition of alkylboranes to alkynoates

• Takamichi Wakamatsu,
• Kazunori Nagao,
• Hirohisa Ohmiya and
• Masaya Sawamura

Beilstein J. Org. Chem. 2015, 11, 2444–2450, doi:10.3762/bjoc.11.265

• , 0.289 mmol) and (9-BBN-H)2 (33.6 mg, 0.138 mmol) were placed in a vial containing a magnetic stirring bar. The vial was sealed with a Teflon®-coated silicon rubber septum, and the vial was evacuated and filled with argon. 1,4-Dioxane (0.4 mL) was added to the vial, and the mixture was stirred at 60 °C

• for 1 h to prepare an alkylborane 2a. Meanwhile, CuOAc (1.5 mg, 0.0125 mmol), P(OPh)3 (6.9 μL, 0.025 mmol) and t-BuOK (1.4 mg, 0.0125 mmol) were placed in another vial. The vial was sealed with a Teflon®-coated silicon rubber septum, evacuated, and then filled with argon. After 1,4-dioxane (0.6 mL

Size-controlled and redox-responsive supramolecular nanoparticles

• Raquel Mejia-Ariza,
• Gavin A. Kronig and
• Jurriaan Huskens

Beilstein J. Org. Chem. 2015, 11, 2388–2399, doi:10.3762/bjoc.11.260

• images were taken with a Carl Zeiss Merlin scanning electron microscope. The samples were prepared by drop-casting 10 μL of a SNP solution onto a silicon wafer. After 60 s, excess of water was removed by filter paper. The particle dimensions are obtained from SEM images with ImageJ software. For each

Olefin metathesis in air

• Lorenzo Piola,
• Fady Nahra and
• Steven P. Nolan

Beilstein J. Org. Chem. 2015, 11, 2038–2056, doi:10.3762/bjoc.11.221

• conducted in water [31][32]. They discovered that Ru(H2O)6(tos)2 could polymerize 7-oxanorbonene 1 in water under air (Scheme 1). In 1991, Marciniec and Pietraszuck reported the catalytic activity of RuCl2(PPh3)3 in the self-metathesis of silicon-contaning olefins. The reactions were performed with 1 mol

Polythiophene and oligothiophene systems modified by TTF electroactive units for organic electronics

• Alexander L. Kanibolotsky,
• Neil J. Findlay and
• Peter J. Skabara

Beilstein J. Org. Chem. 2015, 11, 1749–1766, doi:10.3762/bjoc.11.191

• -type semiconductor in OFETs using two solvents for spin-coating – chloroform and chlorobenzene [93]. A bottom contact, bottom gate device configuration was used with an n-doped silicon gate and a SiO2 dielectric layer. After annealing at 120 °C, AFM imaging indicated a closely packed grain-like surface

A hybrid electron donor comprising cyclopentadithiophene and dithiafulvenyl for dye-sensitized solar cells

• Gleb Sorohhov,
• Chenyi Yi,
• Michael Grätzel,
• Silvio Decurtins and
• Shi-Xia Liu

Beilstein J. Org. Chem. 2015, 11, 1052–1059, doi:10.3762/bjoc.11.118

• unit. Keywords: donor–acceptor systems; dye-sensitized solar cells; electrochemistry; intramolecular charge transfer; Knoevenagel reaction; tetrathiafulvalene; Introduction Dye-sensitized solar cells (DSSCs) have been intensively investigated as an alternative to silicon-based solar cells [1][2][3][4

Is organic chemistry science – and does this question make any sense at all?

• Andreas Kirschning and
• Thomas A. C. Reydon

Beilstein J. Org. Chem. 2015, 11, 893–896, doi:10.3762/bjoc.11.100

• origin of chirality in bio(macro)molecules and thus in life [12]; the question why biomolecules on earth are based on carbon backbones and not on silicon; the question whether one could imagine other forms of molecular architectures that make up self-repeating systems that develop under evolutionary

Adsorption mechanism and valency of catechol-functionalized hyperbranched polyglycerols

• Stefanie Krysiak,
• Qiang Wei,
• Klaus Rischka,
• Andreas Hartwig,
• Rainer Haag and
• Thorsten Hugel

Beilstein J. Org. Chem. 2015, 11, 828–836, doi:10.3762/bjoc.11.92

• backbone), 39.13 (COCH2CH2C), 37.57 (COCH2CH2C), 32.31 (COCH2CH2C), 31.30 (COCH2CH2C), 24.46 (CCH2CH3 of starter), 7.26 (CCH2CH3 of starter) ppm. TiO2 surface TiO2 slides were prepared by sputtering titanium onto silicon wafers. The sputter process was performed using a commercially available radio

• GMBH, Kirchheim, Germany) and afterwards rinsed with ultrapure water. Tip functionalization The molecule is functionalized to the tip through covalent bonds in a similar manner as previously described [2]. Silicon nitride cantilevers (MLCT, Bruker SPM probes, Camarillo, USA) were first activated in an

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

• high enantioselectivities. Though carbon nucleophiles are used in the majority of the copper-catalyzed ECA reactions of α,β-unsaturated amides and lactams, Procter and co-workers have expanded this methodology to the addition of silicon [96]. This reaction is particularly useful because the silyl group

• can be transformed into a number of functional groups [97]. In Procter’s work, they used a Cu(I)–NHC (N-heterocyclic carbene) system to catalyze the asymmetric transfer of silicon from PhMe2SiBpin [98][99] to α,β-unsaturated amides and lactams through activation of the Si–B bond [96] (Scheme 10

• ). Scheme 10 shows selected examples of the α,β-unsaturated lactams and amides that were used for the 1,4-silylation. Overall, the reactions were achieved in both high yields and enantioselectivities with a variety of substrates. In addition to silicon, much work has been done on the asymmetric 1,4-additon

Synthesis and surface grafting of a β-cyclodextrin dimer facilitating cooperative inclusion of 2,6-ANS

• Lars W. Städe,
• Thorbjørn T. Nielsen,
• Laurent Duroux,
• Reinhard Wimmer,
• Kyoko Shimizu and
• Kim L. Larsen

Beilstein J. Org. Chem. 2015, 11, 514–523, doi:10.3762/bjoc.11.58

• fluorescence spectroscopy that the inclusion of the fluorescent guest into both cavities of the β-CD dimer is maintained when grafted onto a solid surface. Keywords: 2,6-ANS; β-cyclodextrin dimer; silicon dioxide; surface grafting; total internal reflection fluorescence spectroscopy; Introduction Since the

• accessibility for inclusion-complex formation [13]. The research presented here aims to bring the cooperative effects of β-CD dimers to solid silicon dioxide surfaces. Modification of these surfaces allows the introduction of the extraordinary binding affinity and selectivity of CD dimers to silicon wafer

• technology and allows the potential cooperative effects to be exploited within chromatographic applications by grafting to silica gels. Further, silicon dioxide surfaces in the form of quartz and glass allow the detection and monitoring of binding events by optical techniques such as fluorescence

The Shono-type electroorganic oxidation of unfunctionalised amides. Carbon–carbon bond formation via electrogenerated N-acyliminium ions

• Alan M. Jones and
• Craig E. Banks

Beilstein J. Org. Chem. 2014, 10, 3056–3072, doi:10.3762/bjoc.10.323

• of the generated reactive intermediates and assist in the formation of the desired products. Tin, silicon or sulfur-based electroauxiliaries have proved useful in this endeavour. Yoshida and co-workers developed an organothio electroauxiliary that is selectively cleaved under anodic oxidation

• conditions [32][33]. Although the introduction of an electroauxiliary requires an additional synthetic step to prepare, the resulting carbon–tin, carbon–silicon or carbon–sulfur bond has a less positive oxidation potential than an unfunctionalised carbamate. Therefore, exquisite control can be exerted on the

• –silicon bond (when an electroauxiliary is present) or direct carbon–hydrogen bond fission to afford the α-methoxylated product (Scheme 10) [67][68]. The direct anodic oxidation reaction to afford the N-acyliminium ion can be intercepted with a carbon nucleophile enantioselectively when a chiral auxiliary

Organic chemistry on surfaces: Direct cyclopropanation by dihalocarbene addition to vinyl terminated self-assembled monolayers (SAMs)

• Malgorzata Adamkiewicz,
• David O’Hagan and
• Georg Hähner

Beilstein J. Org. Chem. 2014, 10, 2897–2902, doi:10.3762/bjoc.10.307

• -SiCl3 and silicon substrate). In the latter chemical modification of the reactive groups of the pre-coated SAM has to be efficient enough such that a reasonable conversion can be obtained, with chemical specificity and lack of surface degradation. In this respect ‘click’ reactions have become attractive

• reported the formation of high quality vinyl-terminated SAMs generated from the vapour phase by adsorption of octadecyltrichlorosilanes onto silicon wafers [16]. With access to these SAMs it became an objective to explore functional group modification of the vinyl double bond. Carbon–carbon bond formation

• characterised by XPS, contact angle measurements and ellipsometry (see Supporting Information File 1). With XPS elements such as silicon, carbon and oxygen were expected in all cases [16]. In each case control reactions were also carried out on the C18-methyl (Me)-terminated SAMs, to ensure that only the vinyl

Solution processable diketopyrrolopyrrole (DPP) cored small molecules with BODIPY end groups as novel donors for organic solar cells

• Diego Cortizo-Lacalle,
• Calvyn T. Howells,
• Upendra K. Pandey,
• Joseph Cameron,
• Neil J. Findlay,
• Anto Regis Inigo,
• Tell Tuttle,
• Peter J. Skabara and
• Ifor D. W. Samuel

Beilstein J. Org. Chem. 2014, 10, 2683–2695, doi:10.3762/bjoc.10.283

• Keithley 2400 source-measure unit and a Steuernagel AM 1.5 G solar simulator at 100 mW cm−2. The illumination intensity was verified and calibrated with an NREL calibrated mono-silicon detector with KG5 filter. External quantum efficiency (EQE) measurements were performed with an incident photon to charge

The effect of permodified cyclodextrins encapsulation on the photophysical properties of a polyfluorene with randomly distributed electron-donor and rotaxane electron-acceptor units

• Aurica Farcas,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert,
• Flavian Farcas,
• Iuliana Stoica and
• Anton Airinei

Beilstein J. Org. Chem. 2014, 10, 2145–2156, doi:10.3762/bjoc.10.222

• -shaped silicon cantilever with a resonance peak of 88 kHz. For image acquisition from different areas (squares with scanning length, Lsc, ranging from 1 μm to 20 μm), the Nova v.1.26.0.1443 for Solver software was used. The root mean square roughness (Sq) was calculated for all the investigated areas

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

• with symmetry (three mirror symmetry planes about the silicon), (2) bulky alkyl groups with symmetry, and (3) dimethyl-substituted possessing only one mirror plane of symmetry about the silicon. When looking further for trends, we compared two parameters to see if any of them ultimately yielded packing

Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

Influence of cyclodextrin on the UCST- and LCST-behavior of poly(2-methacrylamido-caprolactam)-co-(N,N-dimethylacrylamide)

• Alexander Burkhart and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 1951–1958, doi:10.3762/bjoc.10.203

• accomplished using a TP1 turbidity photometer in a temperature range of 5 to 70 °C. During continuous stirring, the transparency of the sample was determined by a voltage-controlled semiconductor or laser and a silicon photodiode at a wavelength of 590 nm and a heating or cooling rate of 1 °C min−1. The

Biantennary oligoglycines and glyco-oligoglycines self-associating in aqueous medium

• Svetlana V. Tsygankova,
• Alexander A. Chinarev,
• Alexander B. Tuzikov,
• Nikolai Severin,
• Alexey A. Kalachev,
• Juergen P. Rabe,
• Alexandra S. Gambaryan and
• Nicolai V. Bovin

Beilstein J. Org. Chem. 2014, 10, 1372–1382, doi:10.3762/bjoc.10.140

• (Digital Instruments, USA). Commercial silicon nitride cantilevers with force constants of 0.06, 0.12, and 0.32 Nm−1 were used for the measurements in contact mode in liquid cell. Cantilevers with a resonance frequency of about 300 kHz and a force constant of 42 Nm−1 were used for the SFM tapping mode in

Molecular recognition of surface-immobilized carbohydrates by a synthetic lectin

• Melanie Rauschenberg,
• Eva-Corrina Fritz,
• Christian Schulz,
• Tobias Kaufmann and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2014, 10, 1354–1364, doi:10.3762/bjoc.10.138

• HisHis towards immobilized NANA in comparison with the glycosides of glucose (Glc), galactose (Gal) and mannose (Man) (Figure 1). In this study, we exploit the epoxide ring opening reaction of amine-tethered carbohydrates on epoxide-terminated SAMs [42] to print carbohydrate microarrays on silicon and

• silicon oxide surfaces can be obtained in only one step from an epoxy-terminated trimethoxysilane. The most common approaches to fabricate epoxide SAMs is by dip-coating or vapor condensation. However, this leads to the formation of thick films of aggregated molecular layers with undefined surface

• morphology [47][48][49][50]. Therefore, the epoxide SAMs were prepared by the method of Julthongpiput et al. because well-defined monolayers of epoxides on glass and silicon substrates can be obtained by using (3-glycidoxypropyl)trimethoxysilane in toluene [42]. The successful surface modification was

Amino acid motifs in natural products: synthesis of O-acylated derivatives of (2S,3S)-3-hydroxyleucine

• Oliver Ries,
• Martin Büschleb,
• Markus Granitzka,
• Dietmar Stalke and
• Christian Ducho

Beilstein J. Org. Chem. 2014, 10, 1135–1142, doi:10.3762/bjoc.10.113

• , nitrogen = blue, silicon = grey, and hydrogen = white. The other hydrogen atoms are omitted for clarity. Synthesis of stereoisomerically pure amino alcohol 5 [32] and of derivative 6 suitable for X-ray crystallography. Synthesis of (2S,3S)-3-hydroxyleucine building blocks 13a,b useful for N-derivatization

Integration of enabling methods for the automated flow preparation of piperazine-2-carboxamide

• Richard J. Ingham,
• Claudio Battilocchio,
• Joel M. Hawkins and
• Steven V. Ley

Beilstein J. Org. Chem. 2014, 10, 641–652, doi:10.3762/bjoc.10.56

• product. Using a Mettler–Toledo FlowIR™ fitted with a detector with a silicon window (required for visualising the nitrile region of the spectrum, which is blocked by the standard diamond window) the change from nitrile to amide can be observed, providing real-time feedback on the state of the reaction

Direct and indirect single electron transfer (SET)-photochemical approaches for the preparation of novel phthalimide and naphthalimide-based lariat-type crown ethers

• Dae Won Cho,
• Patrick S. Mariano and
• Ung Chan Yoon

Beilstein J. Org. Chem. 2014, 10, 514–527, doi:10.3762/bjoc.10.47

• organosilanes. Among a number of n-electron donors, those that contain α-trialkylsilyl substituents 17 have been observed to undergo ready SET oxidation to generate silicon stabilized cation radicals 18 (Scheme 4). Studies by Yoshida and coworkers [55][56][57][58][59][60][61] have shown that α-silyl cation

• delocalization arising by the orbital overlap, lowers the σC-Si bond dissociation energy and makes the silicon center more electropositive. Consequently, short-lived α-silyl cation radicals typically undergo fast, silophile-promoted desilylation to form the carbon centered free radicals 19 (Scheme 4). Based on

Continuous flow nitration in miniaturized devices

• Amol A. Kulkarni

Beilstein J. Org. Chem. 2014, 10, 405–424, doi:10.3762/bjoc.10.38

• ). The selectivity of the desired product 37 was improved under flow conditions. A continuous flow silicon-glass microreactor equipped with multiple functionalities such as multistream micromixer, reaction channel, large-area cooling chamber, and five integrated miniature temperature sensors was used

• the mixed acids in the conventional approach, the authors used fuming nitric acid. The experimental setup comprised three independent pumps for toluene, fuming nitric acid, and ice-water. The reaction took place in a silicon microreactor consisting of nine reaction channels in parallel (0.25 mm

Deoxygenative gem-difluoroolefination of carbonyl compounds with (chlorodifluoromethyl)trimethylsilane and triphenylphosphine

• Fei Wang,
• Lingchun Li,
• Chuanfa Ni and
• Jinbo Hu

Beilstein J. Org. Chem. 2014, 10, 344–351, doi:10.3762/bjoc.10.32

• activation of the C–Cl bond by PPh3 (Path B). In Path A, PPh3 firstly coordinates the silicon atom of TMSCF2Cl to form activated penta-coordinated silicon species 8 [41] and activates both the C–Si and the C–Cl bond. Next, the release of CF2 leads to silylphosphonium salt 9. Finally, the fragmentation of 9

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

• obtained as the by-product (Scheme 15, Table 6) [249]. The desilylation of the initially formed silicon peroxide followed by cyclization of the hydroperoxide accompanied by the attack on the electrophilic center is another example of the use of the Isayama–Mukaiyama reaction for the synthesis of cyclic

• ) from 2-(3,5,5-trimethyl-1,2-dioxolan-3-yl)acetic acid (151) (Scheme 37) [267]. Dioxolane 155 that contains a free hydroxy group was synthesized by the oxidative desilylation of silicon-containing peroxide 124 with n-Bu4NF and H2O2 (Scheme 38) [259]. Dioxolane 158 with the aminoquinoline antimalarial

Flow microreactor synthesis in organo-fluorine chemistry

• Hideki Amii,
• Aiichiro Nagaki and
• Jun-ichi Yoshida

Beilstein J. Org. Chem. 2013, 9, 2793–2802, doi:10.3762/bjoc.9.314

• most efficient reagents for peptide bond formation. Seeberger and co-workers demonstrated the use of a silicon-based microreactor for the effective synthesis of peptides (Scheme 8) [68]. The condensation reaction completed in only 3 min at 90 °C to afford the dipeptide in high yield. Under the