Coupled chemo(enzymatic) reactions in continuous flow

• Ruslan Yuryev,
• Simon Strompen and
• Andreas Liese

Beilstein J. Org. Chem. 2011, 7, 1449–1467, doi:10.3762/bjoc.7.169

• D-28 by a transketolase-catalyzed reaction with added D,L-25. Catalase was used to regenerate the reduced cofactor FADH by oxidation with oxygen. In order to decrease enzyme deactivation caused by shear forces, a bubble-free aeration through a silicon membrane was implemented. A space-time yield of

• biofilm membrane reactor (Scheme 24) [52][53]. Cells of Pseudomonas sp. were grown in a biofilm attached to the inner surface of a silicon tube, through which a nutrient solution was constantly pumped. In a specially designed hermetic reaction compartment the tube was partially submerged into liquid 73

Scaling up of continuous-flow, microwave-assisted, organic reactions by varying the size of Pd-functionalized catalytic monoliths

• Ping He,
• Stephen J. Haswell,
• Paul D. I. Fletcher,
• Stephen M. Kelly and
• Andrew Mansfield

Beilstein J. Org. Chem. 2011, 7, 1150–1157, doi:10.3762/bjoc.7.133

• any observable change in the reaction conversion. Results and Discussion Synthesis of silica monolith and Pd-supported silica monolith catalyst The reaction parameters, such as polymer concentration, acid strength, water content, amount of silicon alkoxide, reaction temperature and reaction time, all

Intramolecular hydroamination of alkynic sulfonamides catalyzed by a gold–triethynylphosphine complex: Construction of azepine frameworks by 7-exo-dig cyclization

• Hideto Ito,
• Tomoya Harada,
• Hirohisa Ohmiya and
• Masaya Sawamura

Beilstein J. Org. Chem. 2011, 7, 951–959, doi:10.3762/bjoc.7.106

• mixture. The tube was sealed with a cap equipped with a Teflon-coated silicon rubber septum. The tube was taken from the glove box, and was placed in a water bath (25 °C). After the reaction was complete (as monitored by TLC), the reaction mixture was passed through a pad of silica gel and was

Homoallylic amines by reductive inter- and intramolecular coupling of allenes and nitriles

• Peter Wipf and
• Marija D. Manojlovic

Beilstein J. Org. Chem. 2011, 7, 824–830, doi:10.3762/bjoc.7.94

• reagent to allylzirconocenes, transient allylzinc intermediates can be successfully added to phosphoryl- and sulfonylimines to provide homoallylic amines in good yields and diastereoselectivities [15]. Of particular interest was the reaction of tin- or silicon-substituted allenes that furnish bis-metallic

Gold-catalyzed alkylation of silyl enol ethers with ortho-alkynylbenzoic acid esters

• Haruo Aikawa,
• Tetsuro Kaneko,
• Naoki Asao and
• Yoshinori Yamamoto

Beilstein J. Org. Chem. 2011, 7, 648–652, doi:10.3762/bjoc.7.76

• ; Findings Silyl enol ethers have been widely used in organic synthesis as effective carbon nucleophiles for the construction of carbon frameworks [1][2][3][4]. Generally, they react with a variety of electrophiles to give carbonyl compounds as products due to cleavage of the silicon–oxygen bond. For example

• complex 8 as a leaving compound [43][44][45][46]. In the case of ordinary substitution reactions with alkyl halides (path a in Scheme 1), generated halide ions would attack the silyl group, due to their strong affinities with the silicon atom, and cleave the silicon–oxygen bond of 7. However, in the

Stereogenic boron in 2-amino-1,1-diphenylethanol-based boronate–imine and amine complexes

• Sebastian Schlecht,
• Walter Frank and
• Manfred Braun

Beilstein J. Org. Chem. 2011, 7, 615–621, doi:10.3762/bjoc.7.72

• hetero elements has been investigated thoroughly for compounds with stereogenic sulfur [1], phosphorus [2], nitrogen [3] and silicon atoms [4]. By comparison, stereogenic tetrahedral-coordinated boron has been studied to a much lesser extent. This is partly because it was incorporated in a chiral

Unusual behavior in the reactivity of 5-substituted-1H-tetrazoles in a resistively heated microreactor

• Bernhard Gutmann,
• Toma N. Glasnov,
• Tahseen Razzaq,
• Walter Goessler,
• Dominique M. Roberge and
• C. Oliver Kappe

Beilstein J. Org. Chem. 2011, 7, 503–517, doi:10.3762/bjoc.7.59

• = 0.0832 × 10−3 s−1 at 240 °C (Figure 3). Control experiments in a microwave reaction vial constructed from strongly microwave absorbing silicon carbide (SiC), which shields the vessel contents from the electromagnetic field and therefore mimics a conventionally heated autoclave experiment, provided

• at 215 nm. The experiments were carried out either in a standard 10 mL Pyrex tube or a vessel made from sintered silicon carbide and gave identical results. Bechamp reduction (Table 1) A 0 M, 0.25 M, 0.5 M and 1 M aqueous HCl solution in ethanol was prepared from conc. HCl and ethanol. A sample of 1

Reciprocal polyhedra and the Euler relationship: cage hydrocarbons, C_nH_n and closo-boranes [B_xH_x]²⁻

• Michael J. McGlinchey and
• Henning Hopf

Beilstein J. Org. Chem. 2011, 7, 222–233, doi:10.3762/bjoc.7.30

• polycycloalkanes have been constructed from other elemental species: Clusters containing lithium, transition metals, silicon, phosphorus, arsenic, bismuth, lead, etc. have been characterized [61][62][63][64], and their architectures continue to delight us. The existence of molecules of such exquisite symmetry

Self-assembly and semiconductivity of an oligothiophene supergelator

• Pampa Pratihar,
• Suhrit Ghosh,
• Vladimir Stepanenko,
• Sameer Patwardhan,
• Ferdinand C. Grozema,
• Laurens D. A. Siebbeles and
• Frank Würthner

Beilstein J. Org. Chem. 2010, 6, 1070–1078, doi:10.3762/bjoc.6.122

• air. Silicon cantilevers (Olympus Corporation, Japan) with a resonance frequency of ~300 kHz and spring constant of ~42 N/m were used. A solution of T1 in methylcyclohexane (MCH) with a concentration of 2 × 10−3 M was spin-coated onto highly oriented pyrolytic graphite (HOPG) at 6000 rpm. The sample

Kinetics and mechanism of vanadium catalysed asymmetric cyanohydrin synthesis in propylene carbonate

• Michael North and
• Marta Omedes-Pujol

Beilstein J. Org. Chem. 2010, 6, 1043–1055, doi:10.3762/bjoc.6.119

• silicon species [82] or the formation of cyanide anions. The most effective catalysts possess both Lewis acidity and Lewis basicity and so can simultaneously activate both the aldehyde and TMSCN [1]. We have recently shown [52] that a Hammett analysis correlating the rate of reaction of meta- and para

• largely be located on silicon as shown in Figure 8a. This was found to be the case (ρ = +0.4) for asymmetric cyanohydrin synthesis catalysed by bimetallic aluminium(salen) complex 6 in the presence of triphenylphosphine oxide [83][84], indicating that most of the catalysis in this case was due to

Formation of epoxide-amine oligo-adducts as OH-functionalized initiators for the ring-opening polymerization of ε-caprolactone

• Julia Theis and
• Helmut Ritter

Beilstein J. Org. Chem. 2010, 6, 938–944, doi:10.3762/bjoc.6.105

• provided with a magnetic stirring bar was loaded with diglycidyl ether of bispenol A (1) (1.702 g, 5.00 mmol) and 4-nitroanisole (2) (0.766 g, 5.00 mmol). The solids were dissolved in 4-methyl-1-cyclohexene (2.404 g, 25.0 mmol). After the addition of 10% Pd/C (125 mg) the tube was sealed with a silicon

Pyridinium based amphiphilic hydrogelators as potential antibacterial agents

• Sayanti Brahmachari,
• Sisir Debnath,
• Sounak Dutta and
• Prasanta Kumar Das

Beilstein J. Org. Chem. 2010, 6, 859–868, doi:10.3762/bjoc.6.101

• few hours under vacuum before imaging. The morphology of the dried gel of compound 2 was also studied using AFM (Veeco, model AP0100) in the non-contact mode. A piece of gel was mounted on a silicon wafer and dried for a few hours under vacuum before imaging. Fluorescence spectroscopy The emission

Aromatic and heterocyclic perfluoroalkyl sulfides. Methods of preparation

• Vladimir N. Boiko

Beilstein J. Org. Chem. 2010, 6, 880–921, doi:10.3762/bjoc.6.88

• analogues continues to grow. Previous reviews in this area are either dated [19] or focus on specialist aspects such as perfluoroalkyl radicals [20][21][22], fluorinated carbanions [23], organometallic compounds [24][25], perfluoroalkyl sulfenyl halides [26], perfluoroalkyl silicon reagents [27][28][29][30

CAAC Boranes. Synthesis and characterization of cyclic (alkyl) (amino) carbene borane complexes from BF₃ and BH₃

• Julien Monot,
• Louis Fensterbank,
• Max Malacria,
• Emmanuel Lacôte,
• Steven J. Geib and
• Dennis P. Curran

Beilstein J. Org. Chem. 2010, 6, 709–712, doi:10.3762/bjoc.6.82

• boron [6][7][13]. Most of the first generation carbene-boranes have been made from N-heterocyclic carbenes in which the carbene carbon is stabilized by two donating nitrogen atoms (imidazolylidene, triazolylidene, etc) or other heteroatoms (phosphorous, silicon, oxygen) [14][15][16][17][18]. An

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

•  2a shows a typical XPS wide-scan spectrum of the bare silica support which was unloaded. The spectrum contains the expected peaks from silicon (Si 2s and Si 2p) and oxygen (O 1s, O 2s and the O KLL Auger series). The small C 1s peak shows the presence of typical hydrocarbon surface contaminations

• ]:[O] = 0.152 (nitrogen can be considered as label for the organic adsorption layer and oxygen the label for the silicon support). The coupling of PVAm with the fluorophore group 1 introduces an additional amount of carbonyl groups (carbon atoms of the cyclic amide in structure 1-P) into the organic

Synthesis, electronic properties and self-assembly on Au{111} of thiolated (oligo)phenothiazines

• Adam W. Franz,
• Svetlana Stoycheva,
• Michael Himmelhaus and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2010, 6, No. 72, doi:10.3762/bjoc.6.72

• presence of a gold-coated silicon wafer. Monolayer formation is confirmed by ellipsometry and the results compared to those obtained by force field and DFT calculations. Keywords: cyclic voltammetry; ellipsometry; phenothiazines; SAM; thiols; Introduction Functional organic π-systems [1] are of great

• reveals a large difference of ΔE = 132 mV for the current peaks of the oxidation and the reduction wave. Presumably, the expected third and fourth oxidations coincide and give rise to a combined quasi-reversible peak. Self-assembly and ellipsometry SAMs on a Au{111}-coated silicon wafer substrate were

• of a gold-coated silicon wafer was used to prepare self-assembled monolayers, which were unambiguously characterized by ellipsometry and accompanying force field and DFT calculations. The chemical trigger of gradual thiol liberation enables better control of film formation and adsorption kinetics

Self-assembled ordered structures in thin films of HAT5 discotic liquid crystal

• Piero Morales,
• Jan Lagerwall,
• Paolo Vacca,
• Sabine Laschat and
• Giusy Scalia

Beilstein J. Org. Chem. 2010, 6, No. 51, doi:10.3762/bjoc.6.51

• with an Instec temperature controller allowed the characterization of the phase transitions and the assessment of the orientation of the molecules in thicker samples. AFM investigations were carried out with Quesant Nomad atomic force microscope in tapping mode with super-sharp silicon probes of force

A review of new developments in the Friedel–Crafts alkylation – From green chemistry to asymmetric catalysis

• Magnus Rueping and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2010, 6, No. 6, doi:10.3762/bjoc.6.6

• silicon-based Lewis acids were used as catalysts (Scheme 26). Chan and co-workers developed an efficient Au(III)-catalyzed FC arylation of cinnamyl alcohols 64 and electron-rich arenes such as 2,6-dimethylphenol 65. The authors found that this transformation can be catalyzed by various transition metals

Preparation and Diels–Alder/cross coupling reactions of a 2-diethanolaminoboron- substituted 1,3-diene

• Liqiong Wang,
• Cynthia S. Day,
• Marcus W. Wright and
• Mark E. Welker

Beilstein J. Org. Chem. 2009, 5, No. 45, doi:10.3762/bjoc.5.45

• 2 is by far the most reactive main group element substituted diene we have made in the boron or silicon substituted series to date. What is perhaps even more surprising to us is that this diene 2 is even more reactive than the most reactive cobaloxime substituted diene we ever prepared in our

• citraconic acid derived dienophiles. This diethanolamine boronyl diene 2 once again reacted under much milder conditions and with better regioselectivity than highly reactive silicon substituted dienes we have also reported previously [11]. Lastly, in order to prove that diethanolamine boronyl diene 2 could

Structural studies on encapsulation of tetrahedral and octahedral anions by a protonated octaaminocryptand cage

• I. Ravikumar,
• P. S. Lakshminarayanan,
• E. Suresh and
• Pradyut Ghosh

Beilstein J. Org. Chem. 2009, 5, No. 41, doi:10.3762/bjoc.5.41

• atoms of HSO4− (O8, O10 for N5 and O10, O21 for N8). The rest of the ammonium hydrogen atoms are also involved in effective N–H···O contacts with the hydrogen sulfate as depicted in Figure 6. Description of the Crystal Structure, [(H8L1)8+(HSiF6−)]3(SiF62−)·(HSiF6−)·15H2O (3). Silicon hexafluoride salt

Radical carbonylations using a continuous microflow system

• Takahide Fukuyama,
• Md. Taifur Rahman,
• Naoya Kamata and
• Ilhyong Ryu

Beilstein J. Org. Chem. 2009, 5, No. 34, doi:10.3762/bjoc.5.34

• mixer and a tabular residence time unit. Using V-65 as a radical initiator, we were able to carry out typical tin- or silicon-based radical carbonylation reactions leading to aldehydes, unsymmetrical ketones, and a lactam, in a continuous microflow system. Experimental Typical procedure for radical

Recent progress on the total synthesis of acetogenins from Annonaceae

• Nianguang Li,
• Zhihao Shi,
• Yuping Tang,
• Jianwei Chen and
• Xiang Li

Beilstein J. Org. Chem. 2008, 4, No. 48, doi:10.3762/bjoc.4.48

Ru-catalyzed dehydrogenative coupling of carboxylic acids and silanes - a new method for the preparation of silyl ester

• Guo-Bin Liu and
• Hong-Yun Zhao

Beilstein J. Org. Chem. 2008, 4, No. 27, doi:10.3762/bjoc.4.27

• nucleophilically-labile silyl ester bonds in the main chain are being studied as a new type of degradable functional polymers with the potential for an extremely broad range of degradation behavior through variation in the functionalities attached to the silicon atom. In the design of degradable materials, the

• physical and mechanical properties must be considered for performance in serving the expected function, while degradation rate and degradation products are also very important. Since the lability of a silyl ester linkage is dramatically affected by the substituents attached to the silicon atom, poly(silyl

The use of silicon- based tethers for the Pauson- Khand reaction

• Adrian P. Dobbs,
• Ian J. Miller and
• Saša Martinović

Beilstein J. Org. Chem. 2007, 3, No. 21, doi:10.1186/1860-5397-3-21

• range of silicon-based tethers and promoters have been investigated for use in the development of a silyl-tethered Pauson-Khand reaction. Background Since its discovery in 1973, the Pauson-Khand (P-K) reaction has become one of the principal methods for the construction of cyclopentenones.[1][2

• ] Temporary tethers have long been used to convert an intermolecular reaction to an intramolecular one and thus favour reaction. Silicon is by far the most popular choice of element when considering forming a temporary tether to link two reaction components.[3] This popularity is due to several factors. First

• , the acyclic silicon containing chains are simple to synthesise, such as through the formation of either silyl ethers or acetals, may contain a wide range of functionalities and are stable to a range of different reaction conditions and purification techniques. Second, the silicon tethers remain inert

Allylsilanes in the synthesis of three to seven membered rings: the silylcuprate strategy

• Asunción Barbero,
• Francisco J. Pulido and
• M. Carmen Sañudo

Beilstein J. Org. Chem. 2007, 3, No. 16, doi:10.1186/1860-5397-3-16

• silylcuprate with electrophiles ("the silylcuprate strategy") provides new routes for the synthesis of functionalised allylsilanes, which undergo highly stereocontrolled silicon-assisted intramolecular cyclizations leading to three to seven membered ring-formation. Background Organosilicon compounds and in

• under Lewis acid catalysis. [10] Thus, silicon assisted cyclization of oxoallylsilanes 3–8 in the presence of TiCl4 or EtAlCl2 results in the formation of 3-methylene-1-cyclopentanols 11–14 with a high degree of stereocontrol (Scheme 3). [7] The cis stereochemistry observed in 11 might indicate a

• carbocations β to silicon (the so-called β-effect). A unique feature of the reaction is the invariable formation of an exocyclic double bond by loss of the silicon group. The methylenecyclopentanol moiety is present in the skeleton of some naturally occurring terpene families. Recent work has shown that the