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Search for "reaction mechanisms" in Full Text gives 121 result(s) in Beilstein Journal of Organic Chemistry.

NMR reaction monitoring in flow synthesis

  • M. Victoria Gomez and
  • Antonio de la Hoz

Beilstein J. Org. Chem. 2017, 13, 285–300, doi:10.3762/bjoc.13.31

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  • -on-a-chip approach. Kinetic and mechanistic studies The rapid analysis produced in flow NMR can be used for the detection of reactive intermediates and consequently for studying reaction mechanisms and the rapid optimization of a chemical process. The first example was described by Nakakoshi et al
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Published 14 Feb 2017

Regiochemistry of cyclocondensation reactions in the synthesis of polyazaheterocycles

  • Patrick T. Campos,
  • Leticia V. Rodrigues,
  • Andrei L. Belladona,
  • Caroline R. Bender,
  • Juliana S. Bitencurt,
  • Fernanda A. Rosa,
  • Davi F. Back,
  • Helio G. Bonacorso,
  • Nilo Zanatta,
  • Clarissa P. Frizzo and
  • Marcos A. P. Martins

Beilstein J. Org. Chem. 2017, 13, 257–266, doi:10.3762/bjoc.13.29

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  • intermediates, and from these data it was possible to explain the regiochemistry of the products obtained. Additionally, the data were a useful tool for elucidating the reaction mechanisms. Keywords: DFT-B3LYP; polyazaheterocycles; pyrazinone; pyrido[1,2-a]pyrimidinone; pyrimido[1,2-a]benzimidazole
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Published 10 Feb 2017

Self-optimisation and model-based design of experiments for developing a C–H activation flow process

  • Alexander Echtermeyer,
  • Yehia Amar,
  • Jacek Zakrzewski and
  • Alexei Lapkin

Beilstein J. Org. Chem. 2017, 13, 150–163, doi:10.3762/bjoc.13.18

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  • design the most informative experiments. This approach requires some model structures to be known a priori which may restrict the methodology to reactions with known mechanism, or to empirical parametric models. A discussion of how a priori knowledge of chemistry, i.e., reaction mechanisms, is included
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Published 24 Jan 2017

New approaches to organocatalysis based on C–H and C–X bonding for electrophilic substrate activation

  • Pavel Nagorny and
  • Zhankui Sun

Beilstein J. Org. Chem. 2016, 12, 2834–2848, doi:10.3762/bjoc.12.283

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  • ][76][77][78][79]. Interestingly, such reaction mechanisms are not well understood, and the formation of trace quantities of hydroiodic acid rather than the direct substrate activation by molecular iodine has been frequently invoked to rationalize the outcome of these studies. Recently, Breugst and co
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Published 23 Dec 2016

Combined experimental and theoretical studies of regio- and stereoselectivity in reactions of β-isoxazolyl- and β-imidazolyl enamines with nitrile oxides

  • Ilya V. Efimov,
  • Marsel Z. Shafikov,
  • Nikolai A. Beliaev,
  • Natalia N. Volkova,
  • Tetyana V. Beryozkina,
  • Wim Dehaen,
  • Zhijin Fan,
  • Viktoria V. Grishko,
  • Gert Lubec,
  • Pavel A. Slepukhin and
  • Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2016, 12, 2390–2401, doi:10.3762/bjoc.12.233

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  • (path 2) reaction mechanisms for the formation of isoxazolines 3a–c as depicted in Scheme 3, in accordance with the proposed reaction mechanisms of heterocyclic enamines proposed earlier by Elliott and co-workers [36]. Path 1 includes the formation of intermediate A as a result of the electrophilic
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Published 15 Nov 2016

Organometallic chemistry

  • Bernd F. Straub,
  • Rolf Gleiter,
  • Claudia Meier and
  • Lutz H. Gade

Beilstein J. Org. Chem. 2016, 12, 2216–2221, doi:10.3762/bjoc.12.213

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  • investigation of more active and more selective homogeneous catalysts, catalytic transformations in the total synthesis of natural products, the theoretical and kinetic unravelling of reaction mechanisms, and the verification of rare coordination modes. These various facets underline the importance of
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Editorial
Published 19 Oct 2016

A flow reactor setup for photochemistry of biphasic gas/liquid reactions

  • Josef Schachtner,
  • Patrick Bayer and
  • Axel Jacobi von Wangelin

Beilstein J. Org. Chem. 2016, 12, 1798–1811, doi:10.3762/bjoc.12.170

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  • considered that potential excitation of other reagents could trigger competitive reaction mechanisms and pathways. The LEDs were mounted on an aluminium rod which is water-cooled from the interior to prevent (over-)heating of the LEDs and the reaction (Figure 3). White light was obtained from a commercial
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Published 11 Aug 2016

Rearrangements of organic peroxides and related processes

  • Ivan A. Yaremenko,
  • Vera A. Vil’,
  • Dmitry V. Demchuk and
  • Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

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Published 03 Aug 2016

Cp2TiCl/D2O/Mn, a formidable reagent for the deuteration of organic compounds

  • Antonio Rosales and
  • Ignacio Rodríguez-García

Beilstein J. Org. Chem. 2016, 12, 1585–1589, doi:10.3762/bjoc.12.154

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  • multiple applications of the deuterated compound such as the enhancement of the metabolic stability of pharmaceutical drugs, the use of internal standards for mass spectrometry, the elucidation of biosynthetic pathways, and the study of reaction mechanisms and selectivity control reactions. In an effort to
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Commentary
Published 25 Jul 2016

One-pot synthesis of 4′-alkyl-4-cyanobiaryls on the basis of the terephthalonitrile dianion and neutral aromatic nitrile cross-coupling

  • Roman Yu. Peshkov,
  • Elena V. Panteleeva,
  • Wang Chunyan,
  • Evgeny V. Tretyakov and
  • Vitalij D. Shteingarts

Beilstein J. Org. Chem. 2016, 12, 1577–1584, doi:10.3762/bjoc.12.153

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  • mechanisms within cross-coupling: heterolytic addition of dianion 12− (SNH) to nitrile 2, and/or electron transfer from 12− to 2 followed by recombination or relaxation in the primary pair of radical anions 1·− and 2·− (Scheme 2). These probable reaction mechanisms were studied in [23][24] and are beyond
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Published 25 Jul 2016

Biosynthesis of oxygen and nitrogen-containing heterocycles in polyketides

  • Franziska Hemmerling and
  • Frank Hahn

Beilstein J. Org. Chem. 2016, 12, 1512–1550, doi:10.3762/bjoc.12.148

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  • any cofactors, in spite of its flavin adenine dinucleotide (FAD) binding site [98][99]. The reaction mechanisms and biosynthetic enzymes involved in the rearrangement of versicolorin B (106) to demethylsterigmatocystin (107) have also been discussed controversely. Up to four genes (aflM, aflN, aflX
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Published 20 Jul 2016

The EIMS fragmentation mechanisms of the sesquiterpenes corvol ethers A and B, epi-cubebol and isodauc-8-en-11-ol

  • Patrick Rabe and
  • Jeroen S. Dickschat

Beilstein J. Org. Chem. 2016, 12, 1380–1394, doi:10.3762/bjoc.12.132

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  • EIMS fragmentation mechanisms of the two sesquiterpene ethers corvol ethers A and B, and the sesquiterpene alcohols epi-cubebol and isodauc-8-en-11-ol. Keywords: bacteria; isotopic labelling; mass spectrometry; reaction mechanisms; terpenes; Introduction Gas chromatography coupled to electron impact
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Published 05 Jul 2016

Strecker degradation of amino acids promoted by a camphor-derived sulfonamide

  • M. Fernanda N. N. Carvalho,
  • M. João Ferreira,
  • Ana S. O. Knittel,
  • Maria da Conceição Oliveira,
  • João Costa Pessoa,
  • Rudolf Herrmann and
  • Gabriele Wagner

Beilstein J. Org. Chem. 2016, 12, 732–744, doi:10.3762/bjoc.12.73

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  • occurs before the TS in both cases. In contrast to these concerted reaction mechanisms, the decarboxylation of the zwitterions 5 and 6 appears to have a very low or near to zero activation barrier and is likely to dominate the reaction pattern. We therefore looked more closely to the products of the
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Published 18 Apr 2016

Diradical reaction mechanisms in [3 + 2]-cycloadditions of hetaryl thioketones with alkyl- or trimethylsilyl-substituted diazomethanes

  • Grzegorz Mlostoń,
  • Paulina Pipiak and
  • Heinz Heimgartner

Beilstein J. Org. Chem. 2016, 12, 716–724, doi:10.3762/bjoc.12.71

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  • . Remarkably, in no single case, the ‘head-to-head dimerization’ of aryl/hetaryl and dihetaryl substituted thiocarbonyl ylides was observed. Keywords: [3 + 2]-cycloadditions; diazoalkanes; diradicals; 1,3-dithiolanes; reaction mechanisms; thioketones; Introduction Cycloaddition reactions belong to the most
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Published 14 Apr 2016

Dynamic behavior of rearranging carbocations – implications for terpene biosynthesis

  • Stephanie R. Hare and
  • Dean J. Tantillo

Beilstein J. Org. Chem. 2016, 12, 377–390, doi:10.3762/bjoc.12.41

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  • these aspects of reaction mechanisms. Unique potential energy surface topologies associated with these rearrangements have been discovered in recent years that are not only of fundamental interest, but also provide insight into the way Nature manipulates chemical space to accomplish specific chemical
  • available today), this study paved the way for future dynamics studies and correctly predicted that “similar findings will arise for many other reactions … and interpretation of reaction mechanisms ought to consider the effects of dynamics explicitly” [46]. In light of more recent studies (e.g., see below
  • product following an ambimodal TSS due to dynamic matching. Right: an intermediate that is rapidly passed through or bypassed as a result of dynamic matching. The tetramethylbromonium ion system [14]. The reaction mechanisms of interest in the PES and dynamics studies of Dupuis and co-workers (R = CH3
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Published 29 Feb 2016

Enabling technologies and green processes in cyclodextrin chemistry

  • Giancarlo Cravotto,
  • Marina Caporaso,
  • Laszlo Jicsinszky and
  • Katia Martina

Beilstein J. Org. Chem. 2016, 12, 278–294, doi:10.3762/bjoc.12.30

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  • milling conditions favours SN2 reactions; however it is also true that a solventless environment does not necessarily mean that there is a lack of solution in a liquid phase. Some reaction mixture components can often be liquid, while solvent effects or mixed SN2 and SN1-type reaction mechanisms cannot be
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Published 15 Feb 2016

A journey in bioinspired supramolecular chemistry: from molecular tweezers to small molecules that target myotonic dystrophy

  • Steven C. Zimmerman

Beilstein J. Org. Chem. 2016, 12, 125–138, doi:10.3762/bjoc.12.14

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  • wonderful mistake that led to my learning an enormous amount of exciting synthetic chemistry. Indeed, in going to Columbia University for graduate school I had every intention of working for Professor Gilbert Stork or W. Clark Still. But Professor Ronald Breslow’s enzyme reaction mechanisms course, my first
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Published 25 Jan 2016

Copper-catalysed asymmetric allylic alkylation of alkylzirconocenes to racemic 3,6-dihydro-2H-pyrans

  • Emeline Rideau and
  • Stephen P. Fletcher

Beilstein J. Org. Chem. 2015, 11, 2435–2443, doi:10.3762/bjoc.11.264

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  • assistance of a design of experiments statistical approach (83% ee, 12% yield). 1H NMR spectroscopy was used to gain insight into the reaction mechanisms. Keywords: allylic alkylation; asymmetric catalysis; copper; design of experiments; dynamic kinetic asymmetric transformation; heterocycles; Schwartz
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Published 03 Dec 2015

Computational study of productive and non-productive cycles in fluoroalkene metathesis

  • Markéta Rybáčková,
  • Jan Hošek,
  • Ondřej Šimůnek,
  • Viola Kolaříková and
  • Jaroslav Kvíčala

Beilstein J. Org. Chem. 2015, 11, 2150–2157, doi:10.3762/bjoc.11.232

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  • valuable in the study of reaction mechanisms. In particular, the use of time-efficient DFT methods for the theoretical study of alkene metathesis has been extensively reviewed [9][10][11] and computational results have been found to agree well with recent experimental mechanistic studies based on easily
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Published 10 Nov 2015

A convenient four-component one-pot strategy toward the synthesis of pyrazolo[3,4-d]pyrimidines

  • Mingxing Liu,
  • Jiarong Li,
  • Hongxin Chai,
  • Kai Zhang,
  • Deli Yang,
  • Qi Zhang and
  • Daxin Shi

Beilstein J. Org. Chem. 2015, 11, 2125–2131, doi:10.3762/bjoc.11.229

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  • results in hand, two possible reaction mechanisms were proposed and shown in Scheme 3. 5-Aminopyrazole-4-carbonitrile 6 was obtained from the reaction of hydrazine 1 and methylenemalononitrile 2 through nucleophilic addition, cyclization and aromatization. The nucleophilic attack of the amino group of 6
  • pyrazolo[3,4-d]pyrimidines. Synthesis of 5a from different intermediates. Possible reaction mechanisms for the formation of pyrazolo[3,4-d]pyrimidiine. Optimization of the reaction conditionsa. Supporting Information Supporting Information File 544: Experimental section and copies of 1H and 13C NMR
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Published 06 Nov 2015

Copper-catalyzed aerobic radical C–C bond cleavage of N–H ketimines

  • Ya Lin Tnay,
  • Gim Yean Ang and
  • Shunsuke Chiba

Beilstein J. Org. Chem. 2015, 11, 1933–1943, doi:10.3762/bjoc.11.209

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  • . Copper-catalyzed aerobic C–C bond cleavage reactions of N–H ketimines. Proposed reaction mechanisms for the formation of 3a, 4a and 5a, and the reaction of hydroperoxide 6. Formation of bromoketone 6e. Electrophilic cyanation of Grignard reagents with pivalonitrile (1f). Electrophilic cyanation with
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Published 19 Oct 2015

A novel and widespread class of ketosynthase is responsible for the head-to-head condensation of two acyl moieties in bacterial pyrone biosynthesis

  • Darko Kresovic,
  • Florence Schempp,
  • Zakaria Cheikh-Ali and
  • Helge B. Bode

Beilstein J. Org. Chem. 2015, 11, 1412–1417, doi:10.3762/bjoc.11.152

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  • KS is distinct from PpyS but also its evolutionary relationship, even if they produce a similar class of compound. Thus, the phylogenetic analysis is also useful to distinguish between reaction mechanisms of different KS. In order to prove that the identified PpyS homologues are indeed involved in
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Published 12 Aug 2015

Novel carbocationic rearrangements of 1-styrylpropargyl alcohols

  • Christine Basmadjian,
  • Fan Zhang and
  • Laurent Désaubry

Beilstein J. Org. Chem. 2015, 11, 1017–1022, doi:10.3762/bjoc.11.114

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  • reaction mechanisms, we explored different reaction conditions starting from alcohol 21 (Table 2). 1,2-Dichloroethane and dichloromethane (entries 1 and 2, Table 2) gave better yields (27–31% for 22 and 10–16% for 23) compared to THF (entry 3, Table 2). In an effort to understand the role of Re2O7, the
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Published 15 Jun 2015

Switching the reaction pathways of electrochemically generated β-haloalkoxysulfonium ions – synthesis of halohydrins and epoxides

  • Akihiro Shimizu,
  • Ryutaro Hayashi,
  • Yosuke Ashikari,
  • Toshiki Nokami and
  • Jun-ichi Yoshida

Beilstein J. Org. Chem. 2015, 11, 242–248, doi:10.3762/bjoc.11.27

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  • halohydrins and epoxides from alkenes. The method is also useful for synthesizing 18O-labeled epoxides. Synthesis of halohydrins and epoxides through β-haloalkoxysulfonium ions generated by the reaction of alkenes with DMSO-stabilized halogen cations. Proposed reaction mechanisms for the syntheses of
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Published 13 Feb 2015

A new charge-tagged proline-based organocatalyst for mechanistic studies using electrospray mass spectrometry

  • J. Alexander Willms,
  • Rita Beel,
  • Martin L. Schmidt,
  • Christian Mundt and
  • Marianne Engeser

Beilstein J. Org. Chem. 2014, 10, 2027–2037, doi:10.3762/bjoc.10.211

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  • for an extremely broad variety of substances [2], but has also been recognized as a valuable tool for studying reaction mechanisms by transferring species of a reacting solution directly into the gas phase of a mass spectrometer [3][4][5][6][7]. The technique allows glimpses into the reacting solution
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Published 28 Aug 2014
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