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Search for "condensations" in Full Text gives 92 result(s) in Beilstein Journal of Organic Chemistry.

Extrusion – back to the future: Using an established technique to reform automated chemical synthesis

  • Deborah E. Crawford

Beilstein J. Org. Chem. 2017, 13, 65–75, doi:10.3762/bjoc.13.9

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  • successful by ball milling also. Condensation reactions (e.g., Knoevenagel condensations, Michael additions and Aldol reactions) in particular are the most obvious reaction to be successful by extrusion due to its general success in the ball mill, and as their reactions can be accelerated by the simple
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Published 11 Jan 2017
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  • ], or malonate diesters via Claisen condensations followed by hydrolysis and decarboxylation. The greenest routes appear in the [4 + 2] strategy. The three-step route beginning with photochemical ring opening of cyclobutenone to give vinylketene, followed by Diels–Alder addition to ethylene leading to
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Published 16 Nov 2016

Useful access to enantiomerically pure protected inositols from carbohydrates: the aldohexos-5-uloses route

  • Felicia D’Andrea,
  • Giorgio Catelani,
  • Lorenzo Guazzelli and
  • Venerando Pistarà

Beilstein J. Org. Chem. 2016, 12, 2343–2350, doi:10.3762/bjoc.12.227

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  • derivatives of the D-xylo and L-ribo series, respectively C-4 and C-2 epimers of the L-arabino series. Based on these aldol condensations together with the work previously performed on the L-arabino [33] and L-lyxo [34] series, a working mechanism is presented to explain the complete stereocontrol over the
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Published 08 Nov 2016

Effect of the π-conjugation length on the properties and photovoltaic performance of A–π–D–π–A type oligothiophenes with a 4,8-bis(thienyl)benzo[1,2-b:4,5-b′]dithiophene core

  • Ni Yin,
  • Lilei Wang,
  • Yi Lin,
  • Jinduo Yi,
  • Lingpeng Yan,
  • Junyan Dou,
  • Hai-Bo Yang,
  • Xin Zhao and
  • Chang-Qi Ma

Beilstein J. Org. Chem. 2016, 12, 1788–1797, doi:10.3762/bjoc.12.169

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  • (reaction iv), and the final compounds, COOP-nHT-TBDTs 1–4, were obtained by Knoevenagel condensations of CHO-nHT-TBDTs 17–20 with octylcyanoacetate (reaction v). Since all these compounds have multiple alkyl chains, they are soluble in common organic solvents, so that the final compounds can be processed
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Published 10 Aug 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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  • unprecedented, enzyme-bound flavin-N5-oxide 144 (Scheme 21) [137]. The resulting ketone 141 undergoes a Favorskii rearrangement, finally leading to the formation of the δ-lactone moiety. EncM has also been rationalised to participate in the stereoselectivity of the subsequent aldol condensations and the final
  • mechanism for 4-substituted pyran-2-ones shown in Scheme 2e), Dieckmann condensations as well as oxidative ring expansion of tetramates (212, a–d in Scheme 29). Tetramates 209 are formed by Dieckmann condensation (c in Scheme 29). 2.1 Pyridinones 2.1.1 Condensation between carbonyl groups and nitrogen
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Published 20 Jul 2016

Microwave-assisted synthesis of (aminomethylene)bisphosphine oxides and (aminomethylene)bisphosphonates by a three-component condensation

  • Erika Bálint,
  • Ádám Tajti,
  • Anna Dzielak,
  • Gerhard Hägele and
  • György Keglevich

Beilstein J. Org. Chem. 2016, 12, 1493–1502, doi:10.3762/bjoc.12.146

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  • diphenylphosphine oxide to an isonitrile (Scheme 4b) [36][42]. In this paper, we wish to report the results of our investigations on the synthetic protocol utilizing the three-component condensations of primary or secondary amines, orthoformates and >P(O)H species, such as dialkyl phosphites or diphenylphosphine
  • isolated in a yield of 63%. At higher temperatures, decomposition was observed. In the next stage, the MW-assisted reaction of secondary amines was studied with triethyl orthoformate and diethyl phosphite (Scheme 8). The condensations were carried out applying 3.5 equivalents of diethyl phosphite at 125 °C
  • were the same as those in the condensations with diethyl phosphite (125–150 °C, 1 h). Using 2 equivalents of dialkyl phosphite, more or less transesterified (aminomethylene)bisphosphonates (9–11 and 3c) were also formed beside the expected (phenylaminomethylene)bisphosphonates 7a or 7b (Table 6,entries
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Published 19 Jul 2016

Multicomponent reactions: A simple and efficient route to heterocyclic phosphonates

  • Mohammad Haji

Beilstein J. Org. Chem. 2016, 12, 1269–1301, doi:10.3762/bjoc.12.121

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  • . Some of these post-MCR transformations are: intramolecular cycloaddition reactions, Knoevenagel condensations, metathesis reactions, aza-Wittig reactions, Mitsunobu reactions, etc. [21]. Up to now, two review articles have been reported on azaheterocyclic phosphonates [22][23], but no overview article
  • arylamines were found to be effective in this reaction. Eventually, the biological evaluation of the (2H-isoindol-1-yl)phosphonates 74 revealed their potential as HCT-116 inhibitors. 2.2.4 Pyrazolyl- and oxazolylphosphonates: A series of modified Kabachnik–Fields condensations based on the reaction of 6
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Published 21 Jun 2016

Iodine-mediated synthesis of 3-acylbenzothiadiazine 1,1-dioxides

  • Long-Yi Xi,
  • Ruo-Yi Zhang,
  • Lei Shi,
  • Shan-Yong Chen and
  • Xiao-Qi Yu

Beilstein J. Org. Chem. 2016, 12, 1072–1078, doi:10.3762/bjoc.12.101

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  • been developed to synthesize benzothiadiazine 1,1-dioxides and their analogues. The condensations of 2-aminobenzenesulfonamides with urea, isocyanates, carboxylic acid derivatives or other carbonyl reagents are the most used methods [12][13][14][15]. These reactions were usually carried out under harsh
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Published 24 May 2016

A modular approach to neutral P,N-ligands: synthesis and coordination chemistry

  • Vladislav Vasilenko,
  • Torsten Roth,
  • Clemens K. Blasius,
  • Sebastian N. Intorp,
  • Hubert Wadepohl and
  • Lutz H. Gade

Beilstein J. Org. Chem. 2016, 12, 846–853, doi:10.3762/bjoc.12.83

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  • preparation of the ligand systems L1–L3 on a simple construction principle, i.e., only reactions of carbon- or nitrogen-nucleophiles with chlorophosphines, and condensations of amines with aldehydes were employed. For the synthesis of the N-phosphanylformamidine derivatives 2 and 3 we prepared a set of three
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Published 29 Apr 2016

Biosynthesis of α-pyrones

  • Till F. Schäberle

Beilstein J. Org. Chem. 2016, 12, 571–588, doi:10.3762/bjoc.12.56

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  • biosynthesis: The mechanisms of chain elongation resemble each other, and simple building blocks, e.g., acetyl-CoA and malonyl-CoA, are used to build up the molecule [74]. In general both, polyketides and fatty acids are assembled by repeating Claisen-condensations between an activated acyl-starter unit and
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Published 24 Mar 2016

Regiodefined synthesis of brominated hydroxyanthraquinones related to proisocrinins

  • Joyeeta Roy,
  • Tanushree Mal,
  • Supriti Jana and
  • Dipakranjan Mal

Beilstein J. Org. Chem. 2016, 12, 531–536, doi:10.3762/bjoc.12.52

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  • biomimetic aldol condensations [17][18][19][20][21][22][23], and reports on the synthesis of brominated anthraquinones are scare [12][13][14][15]. Having inspired by the convergence and the regiochemical integrity of the Hauser annulation [24][25][26][27][28][29][30], we explored it for the construction of
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Published 16 Mar 2016

Recent advances in N-heterocyclic carbene (NHC)-catalysed benzoin reactions

  • Rajeev S. Menon,
  • Akkattu T. Biju and
  • Vijay Nair

Beilstein J. Org. Chem. 2016, 12, 444–461, doi:10.3762/bjoc.12.47

Graphical Abstract
  • benzoin condensations [18]. The pentafluorophenyltriazolium catalyst 15 featured in the most efficient asymmetric benzoin reaction reported so far. Inoue and co-workers found that it promotes homocoupling of benzaldehyde at a low loading (4 mol %) to afford benzoin in 90% yield and >99% ee (Scheme 6) [19
  • have appeared in the literature. They include homo, crossed, intramolecular and various asymmetric benzoin reactions leading to products that are difficult to access by other means. Aza-benzoin reactions, intramolecular benzoin condensations, use of aldehyde surrogates and use of non-carbonyl
  • electrophiles (nitroso compounds) are some of the developments that revamped the synthetically unattractive, monotonous image of benzoin condensations. The driving force behind this remarkable evolution of benzoin reaction is NHC-catalysis. Benzoin chemistry is well-set to benefit, in the near future, from new
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Published 09 Mar 2016

Recent highlights in biosynthesis research using stable isotopes

  • Jan Rinkel and
  • Jeroen S. Dickschat

Beilstein J. Org. Chem. 2015, 11, 2493–2508, doi:10.3762/bjoc.11.271

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  • may not precisely follow the IUPAC rules. Review Polyketides Polyketide synthases (PKS) are multidomain enzymes that catalyze the formation of natural products via reaction steps similar to fatty acid biosynthesis, in which C2-units are fused in Claisen condensations and modified in an iterative or
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Published 09 Dec 2015

Cathodic hydrodimerization of nitroolefins

  • Michael Weßling and
  • Hans J. Schäfer

Beilstein J. Org. Chem. 2015, 11, 1163–1174, doi:10.3762/bjoc.11.131

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  • the easy access to nitroolefins in large variety, the C–C bond formation with the introduction of two nitro groups in a 1,4-distance and the conversions of the nitro group by reduction to oximes and amines, the conversion into aldehydes and ketones via the Nef reaction and base catalyzed condensations
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Published 14 Jul 2015

Multivalent polyglycerol supported imidazolidin-4-one organocatalysts for enantioselective Friedel–Crafts alkylations

  • Tommaso Pecchioli,
  • Manoj Kumar Muthyala,
  • Rainer Haag and
  • Mathias Christmann

Beilstein J. Org. Chem. 2015, 11, 730–738, doi:10.3762/bjoc.11.83

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  • properties. Hyperbranched polymers like polytriallylsilane or polyglycerol have been used in a wide range of transformations including aldol condensations [22], Suzuki cross-couplings [23] and Diels–Alder reactions [24], to name a few, with metal complexes as catalytically active principle. The advent of
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Published 12 May 2015

3-Glucosylated 5-amino-1,2,4-oxadiazoles: synthesis and evaluation as glycogen phosphorylase inhibitors

  • Marion Donnier-Maréchal,
  • David Goyard,
  • Vincent Folliard,
  • Tibor Docsa,
  • Pal Gergely,
  • Jean-Pierre Praly and
  • Sébastien Vidal

Beilstein J. Org. Chem. 2015, 11, 499–503, doi:10.3762/bjoc.11.56

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  • corresponding ureas and condensation with C-glucosyl-amidoxime 3 afforded the desired 3-glucosylated 5-amino-1,2,4-oxadiazoles 4a–e in moderate yields. Even though these results are modest, they are in agreement with the yields reported in the literature [29] for such condensations. Removal of the benzoate
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Published 17 Apr 2015

The unexpected influence of aryl substituents in N-aryl-3-oxobutanamides on the behavior of their multicomponent reactions with 5-amino-3-methylisoxazole and salicylaldehyde

  • Volodymyr V. Tkachenko,
  • Elena A. Muravyova,
  • Sergey M. Desenko,
  • Oleg V. Shishkin,
  • Svetlana V. Shishkina,
  • Dmytro O. Sysoiev,
  • Thomas J. J. Müller and
  • Valentin A. Chebanov

Beilstein J. Org. Chem. 2014, 10, 3019–3030, doi:10.3762/bjoc.10.320

Graphical Abstract
  • condensations to proceed in various possible directions. The direction control would open pathways for selectively obtaining different classes of heterocyclic compounds [16][17][18][19][20]. Simultaneously, the selectivity will inevitably be dictated by the variation of the reaction conditions [17][18]. Thus
  • formation of dihydroisoxazolopyridine 5c (Table 3, entry 8) whereas the analogous reaction under ultrasonication gave exclusively the benzoxazocine derivative 6c (Table 3, entry 9). Interestingly, such a product dichotomy in condensations under or without ultrasonication was not typical for the other
  • . Some Biginelli-type three-component condensations with salicylaldehyde. Three-component heterocyclization of 5-amino-3-methylisoxazole (1), salicylaldehyde (2) and N-(2-methoxyphenyl)-3-oxobutanamide (3a). Possible pathways for the three-component reaction of 5-amino-3-methylisoxazole (1
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Published 17 Dec 2014

Five-membered ring annelation in [2.2]paracyclophanes by aldol condensation

  • Henning Hopf,
  • Swaminathan Vijay Narayanan and
  • Peter G. Jones

Beilstein J. Org. Chem. 2014, 10, 2021–2026, doi:10.3762/bjoc.10.210

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  • case. Conclusion In summary, we have demonstrated in this study that aldol-type condensations constitute an attractive alternative to prepare [2.2]paracyclophane derivatives with annelated (and functionalized) five-membered rings, making these derivatives easily available for further transformations
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Published 28 Aug 2014

The chemoenzymatic synthesis of clofarabine and related 2′-deoxyfluoroarabinosyl nucleosides: the electronic and stereochemical factors determining substrate recognition by E. coli nucleoside phosphorylases

  • Ilja V. Fateev,
  • Konstantin V. Antonov,
  • Irina D. Konstantinova,
  • Tatyana I. Muravyova,
  • Frank Seela,
  • Roman S. Esipov,
  • Anatoly I. Miroshnikov and
  • Igor A. Mikhailopulo

Beilstein J. Org. Chem. 2014, 10, 1657–1669, doi:10.3762/bjoc.10.173

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  • -D-arabinofuranosyl)-2-chloroadenine (1; clofarabine), 2-amino-9-(2-deoxy-2-fluoro-β-D-arabinofuranosyl)adenine (2a) and 9-(2-deoxy-2-fluoro-β-D-arabinofuranosyl)hypoxanthine (3a) are formed in 67, 49 and 21% yields, respectively (Table 1). The condensations of the phosphate 12a with 2-chloroadenine
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Published 22 Jul 2014

One-pot three-component synthesis and photophysical characteristics of novel triene merocyanines

  • Christian Muschelknautz,
  • Robin Visse,
  • Jan Nordmann and
  • Thomas J. J. Müller

Beilstein J. Org. Chem. 2014, 10, 599–612, doi:10.3762/bjoc.10.51

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  • been accessed by Knoevenagel condensations [12][13][14] or substitution reactions [15][16][17][18]. Still the quest for new synthetic strategies, novel substitution patterns, and eventually unusual properties and effects has become an ongoing challenge for organic synthesis, physical organic chemistry
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Published 05 Mar 2014

Isocyanide-based multicomponent reactions towards cyclic constrained peptidomimetics

  • Gijs Koopmanschap,
  • Eelco Ruijter and
  • Romano V.A. Orru

Beilstein J. Org. Chem. 2014, 10, 544–598, doi:10.3762/bjoc.10.50

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Published 04 Mar 2014

The Flögel-three-component reaction with dicarboxylic acids – an approach to bis(β-alkoxy-β-ketoenamides) for the synthesis of complex pyridine and pyrimidine derivatives

  • Mrinal K. Bera,
  • Moisés Domínguez,
  • Paul Hommes and
  • Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2014, 10, 394–404, doi:10.3762/bjoc.10.37

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  • . Keywords: alkoxyallenes; condensations; DFT calculations; β-ketoenamides; multi-component reactions; olefin metathesis; pyridines; pyrimidines; Introduction Multicomponent reactions (MCRs) generally allow a diversity-oriented fast and efficient access to complex synthetic intermediates and are thus
  • E- and Z-configured enamide moieties [51][52], finally leading to identical products. After these successful multicomponent reactions we investigated the intramolecular condensations of the bis(β-ketoenamides) 13–15 to pyridine and pyrimidine derivatives. Enamides 13 and 14 were treated with
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Published 13 Feb 2014

New developments in gold-catalyzed manipulation of inactivated alkenes

  • Michel Chiarucci and
  • Marco Bandini

Beilstein J. Org. Chem. 2013, 9, 2586–2614, doi:10.3762/bjoc.9.294

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  • process for the formation of new C–O bonds. In this direction numerous examples of metal and Brønsted-acid catalyzed condensations of alcohols, phenols and carboxylic acids to inactivated olefins have been reported [16]. Interestingly, He and co-workers compared the catalytic attitude of TfOH and
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Published 21 Nov 2013

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

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Published 30 Oct 2013

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

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  • is assessed by studying four reactions, all involving formation of products bearing α,β-unsaturated carbonyl moieties; synthesis of 3-acetylcoumarin, Knoevenagel and Claisen–Schmidt condensations, and a Biginelli reaction. In each case it is possible to monitor the reactions and also in one case, by
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Published 11 Sep 2013
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