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Search for "Claisen condensation" in Full Text gives 32 result(s) in Beilstein Journal of Organic Chemistry.

(CF3CO)2O/CF3SO3H-mediated synthesis of 1,3-diketones from carboxylic acids and aromatic ketones

  • JungKeun Kim,
  • Elvira Shokova,
  • Victor Tafeenko and
  • Vladimir Kovalev

Beilstein J. Org. Chem. 2014, 10, 2270–2278, doi:10.3762/bjoc.10.236

Graphical Abstract
  • application of the proposed protocol allowed for the synthesis of selected polysubstituted pyrazoles in a one-pot procedure directly from acids and ketones. Keywords: Claisen condensation; 1,3-diketones; heterocycles; triflic acid; trifluoroacetic acid anhydride; Introduction 1,3-Diketones represent one of
  • the most important class of organic compounds, since they are applied as key structural blocks in organic syntheses, exhibit different kinds of biological activities, and display a broad range of ionophoric properties [1][2][3]. The method most frequently used for 1,3-diketone synthesis is the Claisen
  • condensation, which comprises the C-acylation of the α-position of ketones in the form of their metal enolates, enamines or silyl ethers, with or without a catalyst. To appear as an acylating agent one of the following compounds could be required: acyl halides and acid esters, including formates and oxalates
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Published 26 Sep 2014

Recent applications of the divinylcyclopropane–cycloheptadiene rearrangement in organic synthesis

  • Sebastian Krüger and
  • Tanja Gaich

Beilstein J. Org. Chem. 2014, 10, 163–193, doi:10.3762/bjoc.10.14

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  • tetracycle 283. The carboxylic acid was converted into the corresponding acyl chloride, followed by addition of diazomethane and subsequent Arndt–Eistert homologation [215] to obtain methyl ester 284. Claisen condensation furnished the intermediate β-cyano-ketone, which was subjected to diazotransfer
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Published 16 Jan 2014

Synthesis and biological activities of the respiratory chain inhibitor aurachin D and new ring versus chain analogues

  • Xu-Wen Li,
  • Jennifer Herrmann,
  • Yi Zang,
  • Philippe Grellier,
  • Soizic Prado,
  • Rolf Müller and
  • Bastien Nay

Beilstein J. Org. Chem. 2013, 9, 1551–1558, doi:10.3762/bjoc.9.176

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  • treatment with aniline, a Conrad–Limpach process [22][23][24][25] gave aurachin D (4) in 72% yield. This transformation was performed in toluene under reflux over 3 Å molecular sieves by formation of an imine intermediate, which was cyclized at 250 °C by Claisen condensation. Precipitation of the product by
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Published 31 Jul 2013

Parallel and four-step synthesis of natural-product-inspired scaffolds through modular assembly and divergent cyclization

  • Hiroki Oguri,
  • Haruki Mizoguchi,
  • Hideaki Oikawa,
  • Aki Ishiyama,
  • Masato Iwatsuki,
  • Kazuhiko Otoguro and
  • Satoshi Ōmura

Beilstein J. Org. Chem. 2012, 8, 930–940, doi:10.3762/bjoc.8.105

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  • CoA as a starter unit, modular and iterative assembly of malonate extender units produces a linear tetraketide intermediate capable of being folded in at least two ways [5]. Intramolecular Claisen condensation and subsequent enolization produce phloracetophenone (path A), while aldol condensation
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Published 22 Jun 2012

Organic synthesis using (diacetoxyiodo)benzene (DIB): Unexpected and novel oxidation of 3-oxo-butanamides to 2,2-dihalo-N-phenylacetamides

  • Wei-Bing Liu,
  • Cui Chen,
  • Qing Zhang and
  • Zhi-Bo Zhu

Beilstein J. Org. Chem. 2012, 8, 344–348, doi:10.3762/bjoc.8.38

Graphical Abstract
  • carbonyl carbon atom affords intermediate 7. A subsequent carbon–carbon bond cleavage of the labile α,α-dichloro β-keto amide through a retro-Claisen condensation reaction [41] generates intermediate 8. Finally, the electrophilic attack of a proton on the carbon–carbon double bond resulted in the final
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Published 07 Mar 2012

High chemoselectivity in the phenol synthesis

  • Matthias Rudolph,
  • Melissa Q. McCreery,
  • Wolfgang Frey and
  • A. Stephen K. Hashmi

Beilstein J. Org. Chem. 2011, 7, 794–801, doi:10.3762/bjoc.7.90

Graphical Abstract
  • b). The latter would form intermediate H, which could then either afford product 17 via intramolecular 1,3-dipolar cycloaddition with the olefin, or could form the diene 19 by proton migration. The synthesis of 16 was only possible by a 9-step sequence (Scheme 8). The starting point was a Claisen
  • condensation of ester 20 and tert-butyl acetate (21) in the presence of lithium hexamethyldisilazide as the base. Ketoester 22 was obtained in 56% yield, however, the two-fold addition of 21 could not be suppressed completely and 14% of the corresponding tertiary alcohol 30 was also obtained. Reduction of the
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Published 10 Jun 2011

Application of the diastereoselective photodeconjugation of α,β-unsaturated esters to the synthesis of gymnastatin H

  • Ludovic Raffier and
  • Olivier Piva

Beilstein J. Org. Chem. 2011, 7, 151–155, doi:10.3762/bjoc.7.21

Graphical Abstract
  • dienoate chain. The configuration at the C-2 carbon atom of this precursor was controlled by using a diastereoselective alkylation of an acyl oxazolidinone. In some cases, a Claisen condensation took place and afforded a β-ketoamide in noticeable amounts diminishing the overall yield of the sequence [15
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Published 02 Feb 2011
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