Recent advances in transition metal-catalyzed Csp²-monofluoro-, difluoro-, perfluoromethylation and trifluoromethylthiolation

• Grégory Landelle,
• Armen Panossian,
• Sergiy Pazenok,
• Jean-Pierre Vors and
• Frédéric R. Leroux

Beilstein J. Org. Chem. 2013, 9, 2476–2536, doi:10.3762/bjoc.9.287

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

• photoreactor was developed involving post functionalization of alkene presenting oligomers by thioglycosides [26]. The flow system allows for precise control over the reaction conditions, is easy to scale up and provides efficient irradiation of the samples by virtue of a sub-millimeter path length. Continuous

One-pot sequential synthesis of isocyanates and urea derivatives via a microwave-assisted Staudinger–aza-Wittig reaction

• Diego Carnaroglio,
• Katia Martina,
• Giovanni Palmisano,
• Andrea Penoni,
• Claudia Domini and
• Giancarlo Cravotto

Beilstein J. Org. Chem. 2013, 9, 2378–2386, doi:10.3762/bjoc.9.274

• been optimized under microwave irradiation and the scale-up experiment has been conducted under conventional conditions in a Parr reactor. The final compounds were isolated after simple filtration in almost quantitative overall yields which makes this procedure facile and rapid to execute. Keywords

• a one-pot, sequential synthesis of urea derivatives from alkyl bromides. With the aim to verify the feasibility of the method under conventional heating, the protocol was tested in a Parr reactor (90 mL) for an easier scale-up. Results and Discussion The Staudinger–aza-Wittig reaction is extremely

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

• crowded diimine ligands 3b and 3c were prepared in one step in good yields using a micro-flow technique. One of the advantages of using microreactors is the ease of scale-up. It should be possible to scale-up our developed process by either continuous running or by increasing the number of the

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

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

• chemistry [1], colloidal science [2], natural product chemistry [3], medicinal chemistry [4][5][6], solid-phase peptide synthesis [7] and in the biosciences [8]. Despite the many advantages of this heating method, and the introduction of a wide range of instrumentation [1], the scale up of microwave

• -mediated reactions still poses a number of challenges, in particular as a result of a lack of uniform heating [9]. Scale-up using batch methodologies in open reaction vessels can give excellent yields but might not be appropriate for certain volatile or toxic reagents whereas continuous flow processing

• advantages for scale up, certainly in terms of process intensification or in combination with reagent and scavenger cartridges for multi-step synthesis [11], and is possible using conventionally heated micro- or mesofluidic flow devices [12][13], but is also feasible under microwave dielectric heating

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

• obtained along with its ribbon-like regioisomer 2r’ in a 1:1 ratio and 75% combined yield. In order to demonstrate the utility of the flow process we decided to scale up the synthesis of helical compound 2o. To our delight, we observed that the [5]helicene precursor 1o underwent photocyclization with

• substitution patterns are obtained in good to excellent yields. In addition our first attempts to scale up the flow photocyclization reactions were successful providing the opportunity for multi-gram syntheses. Flow-reactor setup used in the optimization study. Photocyclization of stilbene to phenanthrene

• . Photo-flow synthesis of [5]- and [6]helicenes. aFor experimental details see Supporting Information File 1. bReaction conditions: 1.1 equiv iodine, 20 equiv THF, UV-light, 2 h retention time. Scale up synthesis of the [5]helicene derivative 2o. Proof of principle and screening of reaction conditions

Topochemical control of the photodimerization of aromatic compounds by γ-cyclodextrin thioethers in aqueous solution

• Hai Ming Wang and
• Gerhard Wenz

Beilstein J. Org. Chem. 2013, 9, 1858–1866, doi:10.3762/bjoc.9.217

• photoproduct from aqueous solution by liquid/liquid extraction simplifies the scale up. Yields of photodimer based on the complex were nearly quantitative. The observed supramolecular catalysis was explained by the high pre-organization resulting from the tight packing of the two guests in the cavity, which

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

• 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

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

• direct analytical information about a reaction is obtained, including the formation of by-products and eventually even the reaction kinetics [1][2][3][4]. This information is important to design efficient flow-through experiments and to scale-up a reaction in a continuous process [5][6][7][8][9], which

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

• conditions, a production yield of 20 g EDA day−1 was achieved using a microreactor with an internal volume of 100 μL. Straightforward scale-up or scale-out of microreactor technology renders this method viable for industrial application. Keywords: diazo compounds; diazotization; ethyl diazoacetate (EDA

• immediately used for either batch [13][15] or continuous-flow [16][17] follow-up reactions. Straightforward scale-up or scale-out of microreactor technology renders this method viable for industrial application. Results and Discussion Flow synthesis Ethyl diazoacetate (1) was synthesized from glycine ethyl

A scalable synthesis of the (S)-4-(tert-butyl)-2-(pyridin-2-yl)-4,5-dihydrooxazole ((S)-t-BuPyOx) ligand

• Hideki Shimizu,
• Jeffrey C. Holder and
• Brian M. Stoltz

Beilstein J. Org. Chem. 2013, 9, 1637–1642, doi:10.3762/bjoc.9.187

• synthesis and revised plan. Scale-up synthesis of (S)-t-BuPyOx. Amidation reactions of picolinic acid. Cyclization screen. Supporting Information Materials and methods, auxiliary experimental details, and relevant NMR spectra are provided. Supporting Information File 382: Experimental details

Organocatalytic asymmetric selenofunctionalization of tryptamine for the synthesis of hexahydropyrrolo[2,3-b]indole derivatives

• Qiang Wei,
• Ya-Yi Wang,
• Yu-Liu Du and
• Liu-Zhu Gong

Beilstein J. Org. Chem. 2013, 9, 1559–1564, doi:10.3762/bjoc.9.177

• given yields are isolated yields, and the ee’s were determined by HPLC. X-ray crystallography of 4a catalyzed by (S)-3b. The plausible reaction mechanism. Scale up of the protocol and synthetic application. Optimization of reaction conditions.a Supporting Information Supporting Information File 348

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

• , the reaction temperature was lowered to room temperature by the joint use of both basic and acidic additives to improve the safety of the synthesis, as azides were to be handled as unstable reactants. Scale-up experiments were also performed, which led to the achievement of gram-scale production in a

• transfer [34], shorter reaction times [35][36][37], reduced reagent consumption [38][39][40], improved safety [41][42], and operational simplicity [43]. Furthermore, CF methodologies provide opportunities for a simple and rapid scale-up [44][45] and automation [46][47] of chemical processes. They also tend

• ] and conventional batch experiments [76]. In conventional batch-based chemistry, the scale-up of chemical reactions can be a challenge because the output depends on the batch size. The situation becomes even more complicated when unstable reactants such as azides are handled on a large scale. However

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

• optimization of large area devices is costly and often impossible to achieve. Continuous-flow synthesis enables straight-forward scale-up of materials compared to conventional batch reactions. In this study, poly(3-hexylthiophene), P3HT, was synthesized in a bench-top continuous-flow reactor. Precise control

• -flow synthesis methods offer several advantages over traditional batch methods [14][15][16][17][18]. The scale-up of reactions is not only straightforward in continuous processing, but there are also benefits in high reaction reproducibility through accurate parameter control, superior heating and

• comparable performance to both commercial and batch-synthesized samples. This study paves the way for the continuous-flow synthesis of other polymers using the KCTP method. With efficient synthesis of polymers possible in a benchtop flow reactor, scale-up of such materials will become straight forward

C–C Bond formation catalyzed by natural gelatin and collagen proteins

• Dennis Kühbeck,
• Basab Bijayi Dhar,
• Eva-Maria Schön,
• Carlos Cativiela,
• Vicente Gotor-Fernández and
• David Díaz Díaz

Beilstein J. Org. Chem. 2013, 9, 1111–1118, doi:10.3762/bjoc.9.123

• influence product yield and kinetics, affording the nitroaldol products in both aqueous and organic media under mild conditions. Significantly, the scale-up of the process between 4-nitrobenzaldehyde and nitromethane is successfully achieved at 1 g scale and in good yield. A comparative kinetic study with

• organic media under mild conditions, affording the nitroaldol product in variable yields depending on the aldehyde and nitroalkane nature. Moreover, the scale-up of the process between 4-nitrobenzaldehyde and nitromethane could also be achieved on a 1 g scale and in good yield. A comparative kinetics

From bead to flask: Synthesis of a complex β-amido-amide for probe-development studies

• Kevin S. Martin,
• Cristian Soldi,
• Kellan N. Candee,
• Hiromi I. Wettersten,
• Robert H. Weiss and
• Jared T. Shaw

Beilstein J. Org. Chem. 2013, 9, 260–264, doi:10.3762/bjoc.9.31

• compounds related to LLW62 was developed on Rink resin as part of a “one-bead, one-compound” combinatorial approach for on-bead screening purposes. The current synthesis is carried out in solution and is amenable to scale-up for follow-up studies on LLW62 and investigations of related structures. The key

Peptoids and polyamines going sweet: Modular synthesis of glycosylated peptoids and polyamines using click chemistry

• Daniel Fürniss,
• Timo Mack,
• Frank Hahn,
• Sidonie B. L. Vollrath,
• Katarzyna Koroniak,
• Ute Schepers and
• Stefan Bräse

Beilstein J. Org. Chem. 2013, 9, 56–63, doi:10.3762/bjoc.9.7

• azide during the scale-up of the reaction but this caused a decrease of the overall reaction yields. In all cases, the test reactions were performed starting from D-glucosamine hydrochloride as a model compound for the synthesis of 1,3,4,6-tetra-O-acetyl-N-azidoacetyl-D-glucosamine (Ac4GlcNAz = 1

Flow photochemistry: Old light through new windows

• Jonathan P. Knowles,
• Luke D. Elliott and
• Kevin I. Booker-Milburn

Beilstein J. Org. Chem. 2012, 8, 2025–2052, doi:10.3762/bjoc.8.229

• , in the lab it is often very difficult to scale up above a few grams in a classic immersion-well reactor (see below). It is perhaps then not surprising that synthetic chemists, as potential first-time users, avoid this medium. This in turn leads to the more fundamental problem: synthetic chemists do

• temperature gave high enantioselectivity. The low productivity of the 100 µL microreactor led the reaction to be transferred to an FEP macroflow reactor for further scale-up, which led to hugely increased productivity. This does, however, demonstrate the utility of microreactors for initial screening of

• reaction conditions prior to scale-up [54]. Later work demonstrated that the reaction could be extended to a number of aldehydes with good yields and high to excellent ee’s [55]. Photocatalysis in microreactors can also be applied to gas-phase reactions. For instance, the titanium dioxide photocatalysed

Efficient electroorganic synthesis of 2,3,6,7,10,11-hexahydroxytriphenylene derivatives

• Carolin Regenbrecht and
• Siegfried R. Waldvogel

Beilstein J. Org. Chem. 2012, 8, 1721–1724, doi:10.3762/bjoc.8.196

• density allows a scale-up of this electroorganic synthesis. Cyclic voltammetry Cyclic voltammetry studies show that triphenylene ketal 2a gets more easily oxidized at lower potentials than subunit 1a (Figure 1). The first reversible process at Eox = 1.22 V corresponds to the oxidation of 2a to a radical

Continuous-flow catalytic asymmetric hydrogenations: Reaction optimization using FTIR inline analysis

• Magnus Rueping,
• Teerawut Bootwicha and
• Erli Sugiono

Beilstein J. Org. Chem. 2012, 8, 300–307, doi:10.3762/bjoc.8.32

• pursued. Microreactor technology offers numerous advantages, including precise control of reaction variables, enhanced mixing quality, improved operational safety, reduced reagent consumption and ready scale-up of chemical processes. Due to the high surface-area-to-volume ratios of microstructured

A general and facile one-pot process of isothiocyanates from amines under aqueous conditions

• Nan Sun,
• Bin Li,
• Jianping Shao,
• Weimin Mo,
• Baoxiang Hu,
• Zhenlu Shen and
• Xinquan Hu

Beilstein J. Org. Chem. 2012, 8, 61–70, doi:10.3762/bjoc.8.6

• particularly for highly electron-deficient substrates. This novel and economical method is suitable for scale-up activities. Keywords: aqueous conditions; cyanuric acid; isothiocyanates; one-pot process; organic synthesis; primary amines; Introduction Isothiocyanates are a class of heteroallenic compounds

• . Moreover, to evaluate the procedure for the potential scaling-up capability, we used aniline as test substrate to scale up the synthesis in 1.0 mol scale. It became clear that the desired phenyl isothiocyanate could be conveniently isolated via vacuum distillation (Table 2, entry 9). This experiment

• wide range of primary alkyl and arylamines into their corresponding isothiocyanates in excellent yields and provides promise for further scale-up activities. Morevover, this method is advantageous over many other methods for the synthesis of highly electron-deficient aromatic isothiocyanates

Recent advances in direct C–H arylation: Methodology, selectivity and mechanism in oxazole series

• Cécile Verrier,
• Pierrik Lassalas,
• Laure Théveau,
• Guy Quéguiner,
• François Trécourt,
• Francis Marsais and
• Christophe Hoarau

Beilstein J. Org. Chem. 2011, 7, 1584–1601, doi:10.3762/bjoc.7.187

• direct arylation of oxazole was further improved for scale-up (Scheme 2) [34]. The C2-magnesation of oxazole was first performed with lithium tributylmagnesate at room temperature, and rapid evolution of the C2-magnesated oxazole to a ring-open isonitrile tautomer was evidenced by 1H NMR spectroscopy

Continuous-flow enantioselective α-aminoxylation of aldehydes catalyzed by a polystyrene-immobilized hydroxyproline

• Xacobe C. Cambeiro,
• Rafael Martín-Rapún,
• Pedro O. Miranda,
• Sonia Sayalero,
• Esther Alza,
• Patricia Llanes and
• Miquel A. Pericàs

Beilstein J. Org. Chem. 2011, 7, 1486–1493, doi:10.3762/bjoc.7.172

• ][58][59][60][61][62][63][64][65][66]. It offers as its main advantages facile automation and excellent heat and mass transfer, rendering the scale-up of a process a trivial task, in contrast with the obstacles always met in the scale-up of batch processes [67][68][69][70][71]. The combination of flow

Efficient syntheses of 25,26-dihydrodictyostatin and 25,26-dihydro-6-epi-dictyostatin, two potent new microtubule-stabilizing agents

• María Jiménez,
• Wei Zhu,
• Andreas Vogt,
• Billy W. Day and
• Dennis P. Curran

Beilstein J. Org. Chem. 2011, 7, 1372–1378, doi:10.3762/bjoc.7.161

• place. The synthesis of each fragment is amenable to scale-up and takes ten steps or less. Ten more steps are needed from the start of fragment coupling to the end of the synthesis, providing the target compounds in about 7–8% overall yield. The intramolecular NHK reaction was successful for the

• minor isomer along with about 75% of the target isomer. The subsequent testing data identify 25,26-dihydrodictyostatin and 25,26-dihydro-6-epi-dictyostatin as candidates for scale-up synthesis and further preclinical development. Structures of dictyostatin and selected analogs varying at C6, C16, and

• dictyostatin SAR. Phillips [25], Ramachandran [26] and Gennari [27] have also developed efficient synthetic routes to the natural product or fully functionalized analogs. Based on the biological profile of over 30 analogs of dictyostatin synthesized in Pittsburgh, we selected 6-epi-dictyostatin (1b) for scale