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Search for "lactones" in Full Text gives 159 result(s) in Beilstein Journal of Organic Chemistry.

Iron-catalyzed domino coupling reactions of π-systems

  • Austin Pounder and
  • William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

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  • -lactones [146]. In 2020, Cai and co-workers reported a three-component intermolecular trifluoromethyl-esterification of activated alkenes 115 with NaOTf and aryl carboxylic acids 178 (Scheme 39) [147]. Notably, the use of NaOTf as a CF3 source, compared to pre-prepared trifluoromethylating agents like
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Published 07 Dec 2021

Synthesis of highly substituted fluorenones via metal-free TBHP-promoted oxidative cyclization of 2-(aminomethyl)biphenyls. Application to the total synthesis of nobilone

  • Ilya A. P. Jourjine,
  • Lukas Zeisel,
  • Jürgen Krauß and
  • Franz Bracher

Beilstein J. Org. Chem. 2021, 17, 2668–2679, doi:10.3762/bjoc.17.181

Graphical Abstract
  • cyclic lactones [69]. The intramolecular cyclization of the acyl radical A gives the tricyclic radical species C, which then forms fluorenone (3) after abstraction of a hydrogen radical by an additional equivalent of the tert-butoxy radical. Conclusion In summary, we have demonstrated that the metal-free
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Published 02 Nov 2021

Advances in mercury(II)-salt-mediated cyclization reactions of unsaturated bonds

  • Sumana Mandal,
  • Raju D. Chaudhari and
  • Goutam Biswas

Beilstein J. Org. Chem. 2021, 17, 2348–2376, doi:10.3762/bjoc.17.153

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  • lactones had been synthesized from alkynoic acids via Hg(II)-salt-catalyzed cyclization reaction. For example, simple 4-pentynoic acid derivatives 137 afforded γ-methylene butyrolactones 139 in good yields via the formation of organomercural compounds 138 using catalytic mercuric oxide, mercuric acetate
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Published 09 Sep 2021

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

  • Thiago S. Silva and
  • Fernando Coelho

Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112

Graphical Abstract
  • nucleophiles beyond the usually employed dicarbonyl compounds to cyanoacetates, nitroacetates, fluoroacetates, lactones, lactams, and aromatic and heteroaromatic carbonyl compounds. The reactions were carried out at higher temperatures (120 °C) than used in the previous protocols involving more reactive
  • additions [92]. Using MBH acetates 63 as substrates, olefin hydroallylation products 64 were obtained via E1cB elimination of the acetate leaving group driven by the enolate intermediate (Scheme 25B). Six-membered lactones (Scheme 25A, 65a–c) were obtained in a cascade reaction when alkenyl alcohols were
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Published 07 Jul 2021

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

  • Guido Gambacorta,
  • James S. Sharley and
  • Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

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Published 18 May 2021

Recent advances in palladium-catalysed asymmetric 1,4–additions of arylboronic acids to conjugated enones and chromones

  • Jan Bartáček,
  • Jan Svoboda,
  • Martin Kocúrik,
  • Jaroslav Pochobradský,
  • Alexander Čegan,
  • Miloš Sedlák and
  • Jiří Váňa

Beilstein J. Org. Chem. 2021, 17, 1048–1085, doi:10.3762/bjoc.17.84

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  • acids to 3-methyl-2-cyclohexanone catalysed by L9/Pd(TFA)2 [49]. Addition reaction of phenylboronic acid to various enones, lactones, and chromones catalysed by L9/Pd(TFA)2 [48][51]. Addition reactions of arylboronic acids to substituted chromones and N-Cbz-4-quinolones catalysed by L9/Pd(TFA)2 [51
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Published 10 May 2021

Identification of volatiles from six marine Celeribacter strains

  • Anuj Kumar Chhalodia,
  • Jan Rinkel,
  • Dorota Konvalinkova,
  • Jörn Petersen and
  • Jeroen S. Dickschat

Beilstein J. Org. Chem. 2021, 17, 420–430, doi:10.3762/bjoc.17.38

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  • experiments also led to a suggestion for the mechanism for sulfur incorporation, but further research is required for a deep understanding of TDA biosynthesis. Besides its function as an antibiotic, TDA acts as a signaling molecule, similar to N-acylhomoserine lactones, at concentrations 100 times lower than
  • some of the investigated strains. A series of aldehydes ranging from hexanal (7) to tetradecanal (13) was found in strain specific patterns, with all identified compounds present in the bouquet from C. manganoxidans. A similar series of γ-lactones spanning from pentan-4-olide (14) to dodecan-4-olide
  • (20), in addition to 3-methylbutan-4-olide (21) and 4-methylhex-5-en-4-olide (22), was detected in strain-specific patterns, with almost all of these compounds present in C. marinus; only C. halophilus did not emit lactones. Furans included furan-2-ylmethanol (23), furfural (24), and 2-acetylfuran (25
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Published 11 Feb 2021

3-Acetoxy-fatty acid isoprenyl esters from androconia of the ithomiine butterfly Ithomia salapia

  • Florian Mann,
  • Daiane Szczerbowski,
  • Lisa de Silva,
  • Melanie McClure,
  • Marianne Elias and
  • Stefan Schulz

Beilstein J. Org. Chem. 2020, 16, 2776–2787, doi:10.3762/bjoc.16.228

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  • (Nymphalidae: Danainae) have hairpencils on the forewings (i.e., androconia) that disseminate semiochemicals during courtship. While most ithomiines are known to contain derivatives of pyrrolizidine alkaloids, dihydropyrrolizines, or γ-lactones in these androconia, here we report on a new class of fatty acid
  • ][12]. While dihydropyrrolizines are also used by other Lepidoptera, e.g., danaines [13][14][15] or arctiines [16][17], γ-lactones derived from necic acids are specific to ithomiines of more derived taxa [11]. Past studies of the androconia of Ithomia have reported the presence of 3 in Ithomia
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Published 16 Nov 2020

Bifurcated synthesis of methylene-lactone- and methylene-lactam-fused spirolactams via electrophilic amide allylation of γ-phenylthio-functionalized γ-lactams

  • Tetsuya Sengoku,
  • Koki Makino,
  • Ayumi Iijima,
  • Toshiyasu Inuzuka and
  • Hidemi Yoda

Beilstein J. Org. Chem. 2020, 16, 2769–2775, doi:10.3762/bjoc.16.227

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  • -butyrolactone; spirolactams; Introduction α-Methylene-γ-butyrolactone is a pharmaceutically important motif which is found in a wide variety of bioactive molecules including natural products (Scheme 1a) [1][2][3]. For example, sesquiterpene lactones represented by parthenolide and helenalin have attracted
  • interest because of their useful biological activities, and many synthetic efforts have been made so far [4][5][6]. On the other hand, syntheses and biological evaluation of nonnatural methylene-lactones also have been reported [4][6][7][8]. For instance, Heindel and his co-worker synthesized methylene
  • key reaction (Scheme 1b) [10][11]. More recently, an amide-functionalized allyl boronate was developed as an alternative reagent for the allylstannane [12][13][14][15][16], which led to the syntheses of not only cytotoxic methylene-lactones spiro-fused to a lactam ring (B) but also their analogous
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Published 13 Nov 2020

Recent developments in enantioselective photocatalysis

  • Callum Prentice,
  • James Morrisson,
  • Andrew D. Smith and
  • Eli Zysman-Colman

Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197

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  • photocycloaddition of coumarins 202 (Scheme 31) [89]. The proposed mechanism for this reaction is similar to that proposed by Bach and Krische, proceeding via a key hydrogen bonding complex 203. Interestingly, this catalyst allowed for reactivity with lactones, whereas Bach’s catalysts are limited to lactams. Yoon
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Published 29 Sep 2020

Selective preparation of tetrasubstituted fluoroalkenes by fluorine-directed oxetane ring-opening reactions

  • Clément Q. Fontenelle,
  • Thibault Thierry,
  • Romain Laporte,
  • Emmanuel Pfund and
  • Thierry Lequeux

Beilstein J. Org. Chem. 2020, 16, 1936–1946, doi:10.3762/bjoc.16.160

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  • oxetane 16. The latter was subjected to the HBr/AcOH ring-opening reaction conditions (Scheme 6). Remarkably, the cyclic products β-hydroxymethyl and β-bromomethyl-γ-lactones 17 and 18 were obtained in an 8:92 ratio [32]. This complete reversal of selectivity in comparison with fluoroalkylidene-oxetane 12
  • alkenes E-1d and E-9, was studied either on the bromomethyl (CH2Br) or on the hydroxymethyl (CH2OH) arm, when applicable. First, from a mixture of lactones 15 and 19 substitution on the bromomethyl arm was performed using sodium azide (Scheme 7). The reaction proceeded smoothly in DMF but it proved
  • formation of derivative 10. Mechanism for the formation of dihydrofuran 10. Mechanism for the formation of unsaturated lactones 14 and 15. Opening reaction of ethyl 2-(oxetanyl-3-idene)acetate (16). Functionalization of bromomethyllactone 15 and its analogues. Functionalization by substitution reaction of
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Published 07 Aug 2020

NHC-catalyzed enantioselective synthesis of β-trifluoromethyl-β-hydroxyamides

  • Alyn T. Davies,
  • Mark D. Greenhalgh,
  • Alexandra M. Z. Slawin and
  • Andrew D. Smith

Beilstein J. Org. Chem. 2020, 16, 1572–1578, doi:10.3762/bjoc.16.129

Graphical Abstract
  • with amine nucleophiles allowed access to β-trifluoromethyl-β-hydroxyamides in moderate to good yield as single diastereoisomers in excellent er following purification [61]. Organocatalytic enantioselective aldol approaches using trifluoroacetophenone derivatives. NHC-catalyzed approaches to β-lactones
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Published 30 Jun 2020

The McKenna reaction – avoiding side reactions in phosphonate deprotection

  • Katarzyna Justyna,
  • Joanna Małolepsza,
  • Damian Kusy,
  • Waldemar Maniukiewicz and
  • Katarzyna M. Błażewska

Beilstein J. Org. Chem. 2020, 16, 1436–1446, doi:10.3762/bjoc.16.119

Graphical Abstract
  • ester [9], which is cleaved in the second step, upon solvolysis, forming the final product (Scheme 1). Bromotrimethylsilane (BTMS) is the main reagent in this reaction and is also known for its ability to cleave lactones, epoxides, acetals, and ethers [10]. BTMS also acted as a brominating agent and
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Published 23 Jun 2020

Oxime radicals: generation, properties and application in organic synthesis

  • Igor B. Krylov,
  • Stanislav A. Paveliev,
  • Alexander S. Budnikov and
  • Alexander O. Terent’ev

Beilstein J. Org. Chem. 2020, 16, 1234–1276, doi:10.3762/bjoc.16.107

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  • (products 46a,b, 46m,n), 1,3-diketones (product 46r), as well as lactones (products 46o–q) were used in the oxidative C–O coupling reaction. The coupling of oximes with 1,3-diketones proceeded in lower yields than with 1,3-ketoesters (products 46a and 46r). Despite the presence of t-BuOOH in the system, a
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Published 05 Jun 2020

Anthelmintic drug discovery: target identification, screening methods and the role of open science

  • Frederick A. Partridge,
  • Ruth Forman,
  • Carole J. R. Bataille,
  • Graham M. Wynne,
  • Marina Nick,
  • Angela J. Russell,
  • Kathryn J. Else and
  • David B. Sattelle

Beilstein J. Org. Chem. 2020, 16, 1203–1224, doi:10.3762/bjoc.16.105

Graphical Abstract
  • cattle treated annually is hundreds of millions [1]. Treatment of horses, other equids, and companion animals is also a major use of anthelmintics. Anthelmintic drug discovery has been a continued emphasis in the animal health industry, driven by the spread of resistance to the macrocyclic lactones [2
  • action of anthelmintic compounds, since it has been recognised that we do not fully understand how many anthelmintics work – for example the concentrations of macrocyclic lactones that paralyse worms in vitro are much greater than the concentration achieved by effective doses in vivo [147]. Several
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Published 02 Jun 2020

Activated carbon as catalyst support: precursors, preparation, modification and characterization

  • Melanie Iwanow,
  • Tobias Gärtner,
  • Volker Sieber and
  • Burkhard König

Beilstein J. Org. Chem. 2020, 16, 1188–1202, doi:10.3762/bjoc.16.104

Graphical Abstract
  • forming phosphate esters or polymerization byproducts that bind on the solid carbon matrix [30]. Boehm titrations: Boehm titrations are used for the determination of acidic or basic surface oxygen functional groups of solid materials. The acidic character is caused by carboxyl groups (R–COOH), lactones (R
  • gases were determined by mass spectrometry. In general, each type of surface group decomposes to a defined product such as CO2 from carboxylic acid or lactones and CO from carbonyl, hydroxide, phenol, ether or quinone groups and thus, information on the amounts of oxygen-containing surface groups are
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Published 02 Jun 2020

Copper-catalysed alkylation of heterocyclic acceptors with organometallic reagents

  • Yafei Guo and
  • Syuzanna R. Harutyunyan

Beilstein J. Org. Chem. 2020, 16, 1006–1021, doi:10.3762/bjoc.16.90

Graphical Abstract
  • alkenylaluminium and alkylaluminium reagents to the β-substituted unsaturated conjugated lactams 25 was utilized (Scheme 7B) [32]. Chiral lactones are yet another interesting class of heterocyclic substrates that have attracted great attention because of their usefulness in both organic synthesis and medicinal
  • chemistry. The copper-catalysed ACA of organozinc reagents to 5,6-dihydro-2-pyranone is one of the best methods to obtain chiral lactones. During the past two decades, the research groups of Chan, Hoveyda (who applied an approach depending on the trapping by an aldehyde), Mauduit, and Wang reported a
  • variety of methods employing the chiral ligands L9–L13 that, in combination with copper, efficiently catalysed the ACA of diethylzinc to 5,6-dihydro-2-pyranone (Scheme 8), providing access to chiral β-substituted lactones with high enantioselectivity and conversion [33][34][35][36][37]. Although the
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Published 14 May 2020

Recent advances in Cu-catalyzed C(sp3)–Si and C(sp3)–B bond formation

  • Balaram S. Takale,
  • Ruchita R. Thakore,
  • Elham Etemadi-Davan and
  • Bruce H. Lipshutz

Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67

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  • scope of this silicon addition to unsaturated lactones using copper catalysis together with NHC ligand L16. The ligand used previously to great advantage by the Hoveyda and Oestreich groups for conjugate additions did not yield high ees for these substrates. The authors designed a new NHC possessing
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Published 15 Apr 2020

A green, economical synthesis of β-ketonitriles and trifunctionalized building blocks from esters and lactones

  • Daniel P. Pienaar,
  • Kamogelo R. Butsi,
  • Amanda L. Rousseau and
  • Dean Brady

Beilstein J. Org. Chem. 2019, 15, 2930–2935, doi:10.3762/bjoc.15.287

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  • Daniel P. Pienaar Kamogelo R. Butsi Amanda L. Rousseau Dean Brady Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, PO Wits 2050, Johannesburg, South Africa 10.3762/bjoc.15.287 Abstract The acylation of the acetonitrile anion with lactones and esters in ethereal
  • solvents was successfully exploited using inexpensive KOt-Bu to obtain a variety of β-ketonitriles and trifunctionalized building blocks, including useful O-unprotected diols. It was discovered that lactones react to produce the corresponding derivatized cyclic hemiketals. Furthermore, the addition of a
  • preparation of trifunctionalized building blocks (hydroxylated β-ketonitriles) and valuable β-ketonitriles (including enolizable compounds) in modest to good yields from lactones and esters. We are currently investigating novel applications of diols 1 and 8, as well as the application of this methodology for
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Published 06 Dec 2019

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

  • Munmun Ghosh,
  • Valmik S. Shinde and
  • Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

Graphical Abstract
  • lactonization of diols 51. However, in this method instead of a chiral base, they used 1-azaspiro[5.5]undecane N-oxyl 52 as a radical mediator for modifying the electrodes which resulted in optically active lactones 53 with enantiopurity of up to 99% (conditions B, Scheme 20) [52]. Chiral medium In this section
  • 66 (Scheme 26). Galvanostatic electrolysis of 66 in an undivided cell using a catalytic amount of 67 resulted in the corresponding lactones 68 in moderate yields and good stereoselectivities. The stereoselectivity was proposed to be controlled through the preferential formation of transition state A
  • over B after reaction of the enolates of 66 with chiral iodoarene 67. Steric factors restrict the formation of transition state B, and the reaction preferentially proceeds via transition state A to stereoselectively form the lactones [62]. Chiral catalysts Achieving enantiocontrol in electrochemical
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Published 13 Nov 2019

Nanangenines: drimane sesquiterpenoids as the dominant metabolite cohort of a novel Australian fungus, Aspergillus nanangensis

  • Heather J. Lacey,
  • Cameron L. M. Gilchrist,
  • Andrew Crombie,
  • John A. Kalaitzis,
  • Daniel Vuong,
  • Peter J. Rutledge,
  • Peter Turner,
  • John I. Pitt,
  • Ernest Lacey,
  • Yit-Heng Chooi and
  • Andrew M. Piggott

Beilstein J. Org. Chem. 2019, 15, 2631–2643, doi:10.3762/bjoc.15.256

Graphical Abstract
  • File 1) yielded ten drimane metabolites shown in Figure 1: one trihydroxylated drimane sesquiterpenoid lactone, nanangenine A (1), four drimane lactones bearing C6/C8 acyl chains, nanangenines B, C, D and E (2, 4, 5 and 6), two acylated drimanes bearing isomeric lactones, isonanangenines B and D (3 and
  • Our investigations into unique Australian microbial biodiversity have led to discovery of a family of drimane sesquiterpenoids, the nanangenines, which serve as key chemotaxonomic markers for the novel fungal species, A. nanangensis. Although related drimane sesquiterpenoid lactones have been found in
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Published 05 Nov 2019

An overview of the cycloaddition chemistry of fulvenes and emerging applications

  • Ellen Swan,
  • Kirsten Platts and
  • Anton Blencowe

Beilstein J. Org. Chem. 2019, 15, 2113–2132, doi:10.3762/bjoc.15.209

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  • the formation of several different products, although predominantly enol lactones [47][50][51][52] (Scheme 3). Highly reactive intermediates formed during these reactions (Scheme 3) have only been observed spectroscopically at low temperatures (−55 °C) [52]. Heptafulvenes also undergo reactions with
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Published 06 Sep 2019

Characterization of two new degradation products of atorvastatin calcium formed upon treatment with strong acids

  • Jürgen Krauß,
  • Monika Klimt,
  • Markus Luber,
  • Peter Mayer and
  • Franz Bracher

Beilstein J. Org. Chem. 2019, 15, 2085–2091, doi:10.3762/bjoc.15.206

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  • dehydration of the δ-hydroxy group and some epimers resulting from acid-catalyzed isomerization reactions. In contrast, Vukkum et al. [13] describe, besides lactones 2 and 3, an α,β-unsaturated carboxylic acid 4. Treatment under more drastic conditions (6 M HCl, reflux, 3 h) was reported to result mainly in
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Published 02 Sep 2019

Isolation and characterisation of irinans, androstane-type withanolides from Physalis peruviana L.

  • Annika Stein,
  • Dave Compera,
  • Bianka Karge,
  • Mark Brönstrup and
  • Jakob Franke

Beilstein J. Org. Chem. 2019, 15, 2003–2012, doi:10.3762/bjoc.15.196

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  • Withanolides are steroidal lactones widespread in Nightshade plants with often potent antiproliferative activities. Additionally, the structural diversity of this compound class holds much potential for the discovery of novel biological activity. Here, we report two newly characterised withanolides, named
  • research. An important example is Withania somnifera, also known as ashwaghanda or Indian ginseng, which has been used in Ayurvedic medicine to treat a large variety of ailments [1]. Extensive studies revealed withanolides, a class of steroidal lactones, to be primarily responsible for the medicinal
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Published 23 Aug 2019

A review of the total syntheses of triptolide

  • Xiang Zhang,
  • Zaozao Xiao and
  • Hongtao Xu

Beilstein J. Org. Chem. 2019, 15, 1984–1995, doi:10.3762/bjoc.15.194

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  • -catalyzed lactonization, and iii) construction of the epoxides by a newly developed methodology. The synthesis commenced from the alkylation of tetralone 22 with 3-(2-iodoethyl)dihydrofuran-2(3H)-one (23) to give diastereomeric lactones that subsequently reacted with dimethylamine to afford a 1:1 mixture of
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Published 22 Aug 2019
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