The Eschenmoser coupling reaction under continuous-flow conditions

• Sukhdeep Singh,
• J. Michael Köhler,
• Andreas Schober and
• G. Alexander Groß

Beilstein J. Org. Chem. 2011, 7, 1164–1172, doi:10.3762/bjoc.7.135

• yields. We have used a flow chemistry system to promote the Eschenmoser coupling under enhanced reaction conditions in order to convert the demanding precursors such as S-alkylated secondary thioamides and thiolactames in an efficient way. Under pressurized reaction conditions at about 220 °C, the

• desired Eschenmoser coupling products were obtained within 70 s residence time. The reaction kinetics was investigated and 15 examples of different building block combinations are given. Keywords: activation energy; episulfide; flow chemistry; keto imine; kinetics; S-alkylation; sulfide contraction

• minimum residence time. For small scale synthesis flow chemistry is of great advantage to realize these conditions on the laboratory bench safely [18]. Results and Discussion For the reaction optimization we have focused on a straightforward procedure that finally prevents the isolation of the S-alkylated

A practical microreactor for electrochemistry in flow

• Kevin Watts,
• William Gattrell and
• Thomas Wirth

Beilstein J. Org. Chem. 2011, 7, 1108–1114, doi:10.3762/bjoc.7.127

• different reactions can be carried out successfully using simple protocols. Keywords: diaryliodonium compounds; electrochemistry; flow chemistry; microreactor; Introduction Electrochemical reactions offer a clean route to the formation of anion and cation radical species from neutral organic molecules

Chemistry in flow systems II

• Andreas Kirschning

Beilstein J. Org. Chem. 2011, 7, 1046–1047, doi:10.3762/bjoc.7.119

• did not live up to the original hype. No one can predict the future impact of flow chemistry, but it is an enabling technology that was introduced to the laboratories of synthetic organic chemists around ten years ago and has flourished for about half a decade now. We can draw a parallel with

• highlight three areas. First of all, we have the application to photochemistry, which has the chance of experiencing a renaissance particularly in an industrial environment. Second, flow chemistry lends itself naturally to the synthesis and direct application of reactive intermediates or reactive reagents

• reactor is exposed to these extreme conditions. You are invited to explore this Thematic Series and you will see contributions from some of the most prominent and creative groups in the world working in the field of flow chemistry. Not surprisingly this series has significantly increased in size since the

Continuous flow hydrogenation using polysilane-supported palladium/alumina hybrid catalysts

• Hidekazu Oyamada,
• Takeshi Naito and
• Shū Kobayashi

Beilstein J. Org. Chem. 2011, 7, 735–739, doi:10.3762/bjoc.7.83

• . The catalyst retained high activity for at least 8 h under neat conditions. Keywords: flow chemistry; hydrogenation; polysilane; palladium; reduction; Findings Catalytic hydrogenation is one of the most important methods for the reduction of C–C double and triple bonds, and other functional groups

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

• explanations for these highly unusual rate accelerations are presented. In addition, general aspects of reactor degradation, corrosion and contamination effects of importance to continuous flow chemistry are discussed. Keywords: flow chemistry; heterogeneous catalysis; microreactors; palladium; process

• order to conduct highly exothermic reactions safely [1][2][3][4][5][6][7][8][9]. More recently, following the concepts of “Process Intensification” and “Novel Process Windows” [10][11][12], flow chemistry executed in high-temperature and/or high-pressure regimes have become increasingly popular [13

• effects in flow chemistry are also discussed. Results and Discussion Flow degradation of 5-benzhydryl-1H-tetrazole As a model system for tetrazole formation the microwave-assisted cycloaddition of diphenylacetonitrile (1) with NaN3 was studied (Scheme 1). After considerable experimentation [25] an optimum

Looking forward to volume six

• Jonathan Clayden

Beilstein J. Org. Chem. 2010, 6, No. 1, doi:10.3762/bjoc.6.1

• way within the journal, these papers can be viewed together using the “thematic series” tool on the website. Recent series have covered the topical themes of flow chemistry [1], supramolecular chemistry [2] and liquid crystals [3], and further series on carbohydrate chemistry and on organofluorine

Continuous flow enantioselective arylation of aldehydes with ArZnEt using triarylboroxins as the ultimate source of aryl groups

• Julien Rolland,
• Xacobe C. Cambeiro,
• Carles Rodríguez-Escrich and
• Miquel A. Pericàs

Beilstein J. Org. Chem. 2009, 5, No. 56, doi:10.3762/bjoc.5.56

• transferred to the reacting carbonyl compound. It is to be mentioned that other strategies for the preparation of mixed alkylarylzinc species from cheap organometallic reagents have been developed in recent times and could probably be also used for the same purpose [33][34][35]. Flow chemistry [36][37][38][39

Controlling hazardous chemicals in microreactors: Synthesis with iodine azide

• Johan C. Brandt and
• Thomas Wirth

Beilstein J. Org. Chem. 2009, 5, No. 30, doi:10.3762/bjoc.5.30

• reaction conditions in microreactors. Keywords: azide; flow chemistry; hazardous reagents; microreactor; rearrangement; Introduction Microstructured devices have already found their way into organic synthesis, because they offer various advantages over traditional large-scale chemistry performed in

Continuous flow based catch and release protocol for the synthesis of α-ketoesters

• Alessandro Palmieri,
• Steven V. Ley,
• Anastasios Polyzos,
• Mark Ladlow and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2009, 5, No. 23, doi:10.3762/bjoc.5.23

• impacting on the way we assemble molecules. Of these, flow chemistry technologies are becoming especially important [3][4][5][6][7][8][9][10][11][12][13][14]. For many years, our group [15][16][17][18][19][20][21][22] has been focussed on using immobilised systems [23][24][25][26][27][28][29] to more

• -ketoester product 4 by flowing aqueous acetic acid (step 4) through the in-line column. The overall route constitutes a new flow chemistry example of the catch-react-and-release concept that we have used successfully in other synthesis programmes [101][102][103]. The nitroolefinic esters 1 were originally

• Uniqsis FlowSyn™ unit to achieve multi-step organic synthesis under continuous flow-chemistry conditions. This was accomplished by adapting the device to incorporate immobilised reagents packed in flow tubes, enabling clean transformations without recourse to conventional product work-up or purification

Asymmetric reactions in continuous flow

• Xiao Yin Mak,
• Paola Laurino and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2009, 5, No. 19, doi:10.3762/bjoc.5.19

• materials as solid-supports for catalysts and reagents have been found to be particularly well-suited for flow chemistry [34][35][36]. These rigid structures have large surface areas, leading to improved mass-transfer between the supported catalyst with the liquid phase and do not suffer from large pressure

A biphasic oxidation of alcohols to aldehydes and ketones using a simplified packed- bed microreactor

• Andrew Bogdan and
• D. Tyler McQuade

Beilstein J. Org. Chem. 2009, 5, No. 17, doi:10.3762/bjoc.5.17

• 100 trials without showing any loss of catalytic activity. Keywords: alcohol oxidation; flow chemistry; heterogeneous catalysis; microreactors; TEMPO; Introduction Microreactors have gained attention because they can help run chemical transformations more efficiently, more selectively, and with a

• functionalized with a range of catalysts and works well as packing material for flow chemistry [39]. In this report, we demonstrate the immobilization of TEMPO and its use in a flow system using the Anelli-Montanari protocol for the oxidation of primary and secondary alcohols [30][40]. Our simplified reactor is