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

• Abstract Here we describe the use of a new open-source software package and a Raspberry Pi® computer for the simultaneous control of multiple flow chemistry devices and its application to a machine-assisted, multi-step flow preparation of pyrazine-2-carboxamide – a component of Rifater®, used in the

• treatment of tuberculosis – and its reduced derivative piperazine-2-carboxamide. Keywords: automation; flow chemistry; hydration; hydrogenation; sustainable processing; Introduction Enabling synthesis technologies such as flow chemistry are becoming commonplace in modern laboratories (for recent reviews

• of flow chemistry in synthesis see [1] and [2]). As more groups start to use this technology, there is an increasing demand to expand the capabilities of laboratory apparatus, in particular for the seamless integration of different types of apparatus from different manufacturers so that they can be

Continuous flow nitration in miniaturized devices

• Amol A. Kulkarni

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

• presented herein and discussed in view of their advantages, limitations and applicability of the information towards scale-up. Selected recent patents that disclose scale-up methodologies for continuous flow nitration are also briefly reviewed. Keywords: continuous flow; flow chemistry; nitration; nitric

Continuous-flow Heck synthesis of 4-methoxybiphenyl and methyl 4-methoxycinnamate in supercritical carbon dioxide expanded solvent solutions

• Phei Li Lau,
• Ray W. K. Allen and
• Peter Styring

Beilstein J. Org. Chem. 2013, 9, 2886–2897, doi:10.3762/bjoc.9.325

• ; flow chemistry; Heck; palladium; supercritical carbon dioxide; Introduction The use of cross-coupling reactions between organometallic reagents and organic halides as a straightforward method of carbon–carbon bond formation has gained much popularity over the past three decades. The development of

• system over homogeneously catalysed reactions using complexes with elaborate ligand design, it would also make purification simpler. Results and Discussion Two reactions were studied using continuous flow chemistry as shown in Scheme 1. In both cases 4-iodoanisole was used as the aryl halide. The alkene

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

• inert plastic flow tubes provided flexibility, scale-up production, and improved safety of operation. Using flow chemistry, the conversion of alcohols to fluorides was achieved by Seeberger and Ley, independently (Scheme 2) [44][45][46][47]. Usually, gem-difluorination of ketones by DAST is known to be

• that can be well-controlled and accelerated using flow microreactor systems The success of continuous flow chemistry in organic synthesis has enlarged rapidly last decade. There have been numerous examples using flow microreactors with improvement of chemical conversions and selectivities compared to

Investigating the continuous synthesis of a nicotinonitrile precursor to nevirapine

• Ashley R. Longstreet,
• Suzanne M. Opalka,
• Brian S. Campbell,
• B. Frank Gupton and
• D. Tyler McQuade

Beilstein J. Org. Chem. 2013, 9, 2570–2578, doi:10.3762/bjoc.9.292

• other value added structures that contain complex pyridines. The route terminates in a batch crystallization yielding high purity CAPIC. This outcome is expected to facilitate regulatory implementation of the overall process. Keywords: continuous; flow chemistry; HIV; Knoevenagel; nevirapine

• , flow chemistry allows chemists to expand their window of process operability by working at elevated temperatures and pressures to increase reaction rates and decrease catalyst loadings [30][31][32][33]. Unlike scaling-up batch reactions, which requires additional optimization, scaling-up flow processes

A combined continuous microflow photochemistry and asymmetric organocatalysis approach for the enantioselective synthesis of tetrahydroquinolines

• Erli Sugiono and
• Magnus Rueping

Beilstein J. Org. Chem. 2013, 9, 2457–2462, doi:10.3762/bjoc.9.284

• dihydropyridine as hydrogen source providing the desired products in good yields and with excellent enantioselectivities. Keywords: asymmetric transfer hydrogenation; binolphosphate; continuous-flow reactors; flow chemistry; microreactors; organocatalysis; photochemistry; Introduction Tetrahydroquinolines [1][2

• ][11][12][13][14][15][16][17]. In the past years, continuous-flow chemistry has received considerable attention and microstructured continuous-flow devices have emerged as useful devices for different chemical reactions [18][19][20][21][22]. Microreactor technology offers numerous practical advantages

Synthesis of homo- and heteromultivalent carbohydrate-functionalized oligo(amidoamines) using novel glyco-building blocks

• Felix Wojcik,
• Sinaida Lel,
• Alexander G. O’Brien,
• Peter H. Seeberger and
• Laura Hartmann

Beilstein J. Org. Chem. 2013, 9, 2395–2403, doi:10.3762/bjoc.9.276

• heteromultivalent glycosylation patterns by combining building blocks presenting different mono- and disaccharides. Keywords: continuous flow; flow chemistry: flow synthesis; glycoligands; multivalency; photochemistry; solid-phase synthesis; thiol–ene; thioglycosides; Introduction Multivalent carbohydrate ligand

Micro-flow synthesis and structural analysis of sterically crowded diimine ligands with five aryl rings

• Shinichiro Fuse,
• Nobutake Tanabe,
• Akio Tannna,
• Yohei Konishi and
• Takashi Takahashi

Beilstein J. Org. Chem. 2013, 9, 2336–2343, doi:10.3762/bjoc.9.268

• ligands exerted high polymerization activity in the ethylene homopolymerization and copolymerization of ethylene with polar monomers. Keywords: amidine formation; diimine; flow chemistry; polymerization; Introduction The design of a ligand is a key step in the development of new catalysts because the

Flow synthesis of phenylserine using threonine aldolase immobilized on Eupergit support

• Jagdish D. Tibhe,
• Hui Fu,
• Timothy Noël,
• Qi Wang,
• Jan Meuldijk and
• Volker Hessel

Beilstein J. Org. Chem. 2013, 9, 2168–2179, doi:10.3762/bjoc.9.254

• Jagdish D. Tibhe Hui Fu Timothy Noel Qi Wang Jan Meuldijk Volker Hessel Micro Flow Chemistry and Process Technology, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, the Netherlands 10.3762/bjoc.9.254 Abstract Threonine

• was achieved at 20 minute residence time. Finally, the productivity of the reactor was calculated, extrapolated to parallel run units, and compared with data collected previously. Keywords: Eupergit; flow chemistry; immobilized enzyme; threonine aldolase; Introduction Enzymes are bio-based catalysts

Temperature measurements with two different IR sensors in a continuous-flow microwave heated system

• Jonas Rydfjord,
• Fredrik Svensson,
• Magnus Fagrell,
• Jonas Sävmarker,
• Måns Thulin and
• Mats Larhed

Beilstein J. Org. Chem. 2013, 9, 2079–2087, doi:10.3762/bjoc.9.244

• chemistry applications. Keywords: continuous-flow; flow chemistry; heating; microwave; organic synthesis; temperature; Introduction In organic synthesis, being able to accurately determine the reaction temperature is often of utmost importance [1][2][3]. When using conventional heating the reaction

Flow synthesis of a versatile fructosamine mimic and quenching studies of a fructose transport probe

• Matthew B. Plutschack,
• D. Tyler McQuade,
• Giulio Valenti and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2013, 9, 2022–2027, doi:10.3762/bjoc.9.238

• NBDM, enabling us to measure key photophysical properties that will facilitate future uptake studies. Keywords: flow chemistry; fructose mimic; gluts; NBDM; Introduction The impact of dietary fructose on human health is not well-understood. A growing body of work suggests that those eating diets high

• flow chemistry challenge. The output from the oxime step contains excess hydroxylamine and salts carried from the first step that poisoned the packed-bed catalyst we screened. In theory, continuous purification could remove these materials but existing strategies do not enable removal of water soluble

Microflow photochemistry: UVC-induced [2 + 2]-photoadditions to furanone in a microcapillary reactor

• Sylvestre Bachollet,
• Kimitada Terao,
• Shin Aida,
• Yasuhiro Nishiyama,
• Kiyomi Kakiuchi and
• Michael Oelgemöller

Beilstein J. Org. Chem. 2013, 9, 2015–2021, doi:10.3762/bjoc.9.237

• chemistry; furanone; microflow chemistry; photochemistry; Introduction Continuous-flow chemistry has recently emerged as a new methodology in organic chemistry [1][2][3][4]. The combination of microstructured dimensions and flow operations has also proven advantageous for photochemical applications [5][6

• test tube. The microcapillary unit had a 9-times larger surface-to-volume ratio, which resulted in a more efficient harvest of the available light. The results contribute to the growing field of ‘microflow photochemistry’ [5][6][7][8][9] and ‘green flow chemistry’ [42][43][44][45]. It is hoped that

• photoreactor equipped with low wattage UVC-lamps. Conversion rates and isolated yields were compared to analogue batch reactions in a quartz test tube. In all cases examined, the microcapillary reactor furnished faster conversions and improved product qualities. Keywords: cycloaddition; cyclobutane; flow

One-step synthesis of pyridines and dihydropyridines in a continuous flow microwave reactor

• Mark C. Bagley,
• Vincenzo Fusillo,
• Robert L. Jenkins,
• M. Caterina Lubinu and
• Christopher Mason

Beilstein J. Org. Chem. 2013, 9, 1957–1968, doi:10.3762/bjoc.9.232

• -substituted propargyl aldehydes undergo Hantzsch dihydropyridine synthesis in preference to Bohlmann–Rahtz reaction in a very high yielding process that is readily transferred to continuous flow processing. Keywords: Bohlmann–Rahtz; continuous flow processing; ethynyl ketones; flow chemistry; Hantzsch

• microwave-assisted transformations under flow processing have greatly expanded the range of chemistries scaled up and evaluated using this technology [1][9][16][33][34][35][36][37][38][39][40][41][42]. With all of these developments, it is becoming increasingly clear that flow chemistry, and to some degree

• microwave flow chemistry, is realizing its potential towards the next evolutionary step in synthetic chemistry [43]. In 2005 we described a new continuous flow reactor design for microwave-assisted synthesis that operates in the optimum standing-wave cavity of a proprietary instrument [44]. The principal

Continuous flow photocyclization of stilbenes – scalable synthesis of functionalized phenanthrenes and helicenes

• Quentin Lefebvre,
• Marc Jentsch and
• Magnus Rueping

Beilstein J. Org. Chem. 2013, 9, 1883–1890, doi:10.3762/bjoc.9.221

• backbone functionalized phenanthrenes and helicenes of various sizes in good yields. Keywords: continuous-flow reactor; flow chemistry; helicenes; light-driven cyclization reaction; photocyclization; stilbenes; Introduction Phenanthrenes are versatile intermediates toward polycyclic aromatic hydrocarbons

Raman spectroscopy as a tool for monitoring mesoscale continuous-flow organic synthesis: Equipment interface and assessment in four medicinally-relevant reactions

• Trevor A. Hamlin and
• Nicholas E. Leadbeater

Beilstein J. Org. Chem. 2013, 9, 1843–1852, doi:10.3762/bjoc.9.215

• industry on production scales. In a research and development setting, there has been increasing interest in using flow chemistry on smaller scales. To this end, a wide range of companies now produce equipment for both micro- and mesofluidic flow chemistry [1][2]. Some of the advantages of these devices are

• increased experimental safety, easy scale-up and thorough mixing of reagents [3][4][5][6][7]. It is not surprising, therefore, that a wide range of synthetic chemistry transformations have been reported using this equipment [8][9]. When it comes to evaluating the outcome of reactions performed using flow

• chemistry and optimizing reaction conditions, one option is to use inline product analysis. This opens the avenue for fast, reliable assay in comparison with the traditional approach in which performance is evaluated based on offline product analysis. When interfaced with microreactors, inline analysis has

Integrating reaction and analysis: investigation of higher-order reactions by cryogenic trapping

• Skrollan Stockinger and
• Oliver Trapp

Beilstein J. Org. Chem. 2013, 9, 1837–1842, doi:10.3762/bjoc.9.214

• ; cycloaddition; Diels–Alder reaction; flow chemistry; gas chromatography; on-column reaction gas chromatography; Introduction The combination of synthesis and analysis in a single experiment offers many advantages. Time-consuming steps, i.e. work-up and separation of the reaction products, can be minimized, and

Ethyl diazoacetate synthesis in flow

• Mariëlle M. E. Delville,
• Jan C. M. van Hest and
• Floris P. J. T. Rutjes

Beilstein J. Org. Chem. 2013, 9, 1813–1818, doi:10.3762/bjoc.9.211

• ); flow chemistry; microreactor technology; Introduction Diazo compounds are frequently used versatile building blocks in organic chemistry [1][2]. From this class of compounds diazomethane and ethyl diazoacetate (1, EDA) are arguably the synthetically most useful ones. Due to the potentially explosive

Flow Giese reaction using cyanoborohydride as a radical mediator

• Takahide Fukuyama,
• Takuji Kawamoto,
• Mikako Kobayashi and
• Ilhyong Ryu

Beilstein J. Org. Chem. 2013, 9, 1791–1796, doi:10.3762/bjoc.9.208

• 70 °C in combination with a residence time of 10–15 minutes gave good yields of the desired addition products. Keywords: continuous flow system; cyanoborohydride; flow chemistry; iodoalkanes; microreactor; tin-free Giese reaction; Introduction Organo halides are among the most useful precursors to

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

• application of a monolithic form of triphenylphosphine to the Ramirez gem-dibromoolefination reaction using flow chemistry techniques is reported. A variety of gem-dibromides were synthesised in high purity and excellent yield following only removal of solvent and no further off-line purification. It is also

• possible to perform the Appel reaction using the same monolith and the relationship between the mechanisms of the two reactions is discussed. Keywords: bromination; flow chemistry; Ramirez gem-dibromoolefination reaction; solid-supported reagent; triphenylphosphine monolith; Introduction The advantages

• of applying flow chemistry processing to organic synthesis have been extensively demonstrated in the literature, increasing the safety, efficiency and reproducibility of many organic chemistry reactions, causing this technology to be accepted as an important new tool to aid the modern research

[3 + 2]-Cycloadditions of nitrile ylides after photoactivation of vinyl azides under flow conditions

• Stephan Cludius-Brandt,
• Lukas Kupracz and
• Andreas Kirschning

Beilstein J. Org. Chem. 2013, 9, 1745–1750, doi:10.3762/bjoc.9.201

• from the corresponding vinyl azide. Keywords: azirines; cycloaddition; flow chemistry; flow reactors; inductive heating; nitrile ylides; photochemistry; vinyl azides; Introduction Recently, photochemistry has seen a renaissance despite the fact that under batch conditions specialized reaction vessels

• photochemical process can efficiently be achieved. These facts led us to initiate an investigation on the photochemical activation of vinyl azides and the trapping of the intermediate nitrile ylides 3 [19] by different dipolarophiles exploiting the advantages of photo flow-chemistry [20][21]. Here, we report on

Gallium-containing polymer brush film as efficient supported Lewis acid catalyst in a glass microreactor

• Rajesh Munirathinam,
• Roberto Ricciardi,
• Richard J. M. Egberink,
• Jurriaan Huskens,
• Michael Holtkamp,
• Herbert Wormeester,
• Uwe Karst and
• Willem Verboom

Beilstein J. Org. Chem. 2013, 9, 1698–1704, doi:10.3762/bjoc.9.194

• model substrate, and for the formation of oxazoles by ring closure of ortho-hydroxy oximes. The catalytic activity of the microreactor could be maintained by periodic reactivation by treatment with GaCl3. Keywords: dehydration of oximes; flow chemistry; gallium; microreactors; Lewis acid catalysis

Chemistry in flow systems III

• Andreas Kirschning

Beilstein J. Org. Chem. 2013, 9, 1696–1697, doi:10.3762/bjoc.9.193

• Andreas Kirschning Leibniz University of Hannover, Schneiderberg 1B, 30167 Hannover, Germany 10.3762/bjoc.9.193 Keywords: flow chemistry; The third Thematic Series on flow chemistry published in the Beilstein Journal of Organic Chemistry demonstrates the emerging importance of transforming

• these aspects can be found in this third Thematic Series on flow chemistry. I am thankful to all my colleagues who contributed with their excellent research to this issue. The Beilstein Team is acknowledged for the handling of the manuscripts and referee reports in a very pleasant and professional

The rapid generation of isothiocyanates in flow

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 1613–1619, doi:10.3762/bjoc.9.184

• chemical transformation which typically eliminates the requirements for any conventional work-up or purification of the reaction stream. Keywords: chloroxime; dipolar cycloaddition; flow chemistry; flow synthesis; immobilised reagents; isothiocyanate; nitrile oxide; Introduction Flow based chemical

• ]. Indeed, flow chemistry is moving from an academic curiosity to become a common tool in many synthesis laboratories paralleling the emergence and adoption of another enabling technology, the microwave reactor [17]. An area which has benefited significantly from the many recent developments in our

• understanding of flow chemistry is the synthesis of reactive precursors and handling of sensitive intermediates [18][19][20][21][22][23]. However, despite the breadth of chemistries already explored there are certain functional transformations notably absent, one particular class of important building blocks

Efficient continuous-flow synthesis of novel 1,2,3-triazole-substituted β-aminocyclohexanecarboxylic acid derivatives with gram-scale production

• Sándor B. Ötvös,
• Ádám Georgiádes,
• István M. Mándity,
• Lóránd Kiss and
• Ferenc Fülöp

Beilstein J. Org. Chem. 2013, 9, 1508–1516, doi:10.3762/bjoc.9.172

• safe and straightforward way. The obtained 1,2,3-triazole-substituted β-aminocyclohexanecarboxylates can be regarded as interesting precursors for drugs with possible biological effects. Keywords: β-amino acids; click chemistry; continuous-flow; copper; flow chemistry; triazoles; Introduction In

• to be environmentally benign technologies [48]. In consequence of these benefits, flow chemistry-based techniques have exerted a significant impact on modern synthetic chemistry, ranging from laboratory-based experiments to industrial-scale production. Here, we describe a safe and efficient CF

Controlled synthesis of poly(3-hexylthiophene) in continuous flow

• Helga Seyler,
• Jegadesan Subbiah,
• David J. Jones,
• Andrew B. Holmes and
• Wallace W. H. Wong

Beilstein J. Org. Chem. 2013, 9, 1492–1500, doi:10.3762/bjoc.9.170

• : conjugated polymers; continuous-flow synthesis; controlled polymerization; flow chemistry; organic solar cell materials; Introduction Poly(3-hexylthiophene), P3HT, is the most investigated material in bulk heterojunction (BHJ) organic solar cells (OSC) [1]. The reasons for its dominance in the field include