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Search for "lactone" in Full Text gives 272 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Synthetic strategies toward 1,3-oxathiolane nucleoside analogues

  • Umesh P. Aher,
  • Dhananjai Srivastava,
  • Girij P. Singh and
  • Jayashree B. S

Beilstein J. Org. Chem. 2021, 17, 2680–2715, doi:10.3762/bjoc.17.182

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  • at reflux temperature in toluene to synthesize the 1,3-oxathiolane lactone 6 via intermediate 5 after elimination of a water molecule. This was further reduced with diisobutylaluminum hydride (DIBAL) in toluene at −78 °C or by lithium tri-tert-butoxyaluminum hydride in THF at 0 °C to obtain lactol 7
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Published 04 Nov 2021

Recent advances in the syntheses of anthracene derivatives

  • Giovanni S. Baviera and
  • Paulo M. Donate

Beilstein J. Org. Chem. 2021, 17, 2028–2050, doi:10.3762/bjoc.17.131

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  • alkynes [24][25]. Numerous synthetic routes have also been reported for the synthesis of anthraquinones [26][27][28][29]. On the other hand, preparative methods for dibenzo[a,h]anthracene derivatives are less common, mainly relying on the cyclization of the corresponding lactone derivative followed by
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Published 10 Aug 2021

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

  • Renato L. Carvalho,
  • Amanda S. de Miranda,
  • Mateus P. Nunes,
  • Roberto S. Gomes,
  • Guilherme A. M. Jardim and
  • Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

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  • target lactone in 61% yield over two steps. The final steps involved a one-pot ozonolysis with quenching under Pinnick oxidation conditions to afford the carboxylic acid derivative in 83% yield, followed by White’s selective C–H oxidation (Scheme 26B). White’s selective C–H oxidation was also applied in
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Published 30 Jul 2021

Development of N-F fluorinating agents and their fluorinations: Historical perspective

  • Teruo Umemoto,
  • Yuhao Yang and
  • Gerald B. Hammond

Beilstein J. Org. Chem. 2021, 17, 1752–1813, doi:10.3762/bjoc.17.123

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  • observations are noted: N-Fluoro-2,6-bis(methoxymethyl)pyridinium triflate (5-4l) fluorinated the trimethylsilyl ether of γ-butyrolactone and 1-cyclohexenyl acetate in much higher yields than the N-fluoro-2,4,6-trimethyl salt 5-4j [32]. Thus, as seen in Scheme 13, 5-4l converted the Corey lactone 5-7 via its
  • silyl ether 5-8 to the fluorinated lactone 5-9 in a very satisfactory overall yield [32]. N-Fluoro-2,6-bis(CH2OAc)pyridinium triflate 5-4n [32], N-fluoro-2,6-bis(COOMe)pyridinium triflate 5-4y [30][32], and N-fluoro-2-cyano- and -2,6-dicyanopyridinium tetrafluoroborates [39] were useful reagents, too
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Published 27 Jul 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

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  • employed, and an example of a seven-membered lactone was reported (Scheme 25A, 66). However, in the latter case, acid catalysis and reflux were needed to ensure cyclization. Still taking advantage of the enolate intermediate, the Cui group reported the use of olefins 68, containing tethered leaving groups
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Published 07 Jul 2021

Analogs of the carotane antibiotic fulvoferruginin from submerged cultures of a Thai Marasmius sp.

  • Birthe Sandargo,
  • Leon Kaysan,
  • Rémy B. Teponno,
  • Christian Richter,
  • Benjarong Thongbai,
  • Frank Surup and
  • Marc Stadler

Beilstein J. Org. Chem. 2021, 17, 1385–1391, doi:10.3762/bjoc.17.97

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  • Hz, H-1). The 13C NMR spectrum showed 15 signals including those of a lactone carbonyl at δC 177.6 (C-15); four olefinic carbons at δC 126.0 (C-4), 126.5 (C-2), 133.4 (C-3), and 144.0 (C-1); three methyl groups at δC 8.7 (C-14), 20.2 (C-13), and 28.0 (C-12) (Table 1). The remaining resonances were
  • be attributed to an absence of the α-methylene lactone unit present in fulvoferruginin (1). Nevertheless, the cytotoxicity detected here for fulvoferruginin shows that re-evaluating the bioactivity of previously isolated basidiomycete metabolites in different bioassays can lead to unexpected results
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Published 04 Jun 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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  • ring size, unsaturated lactone, N-protected dihydropyridone and one example of a linear substrate. In all cases a decreased reactivity was observed, however, good to excellent enantioselectivity levels were maintained (81–99% ee; Table 8) [37]. To our best knowledge, at this time only one method for
  • , the addition reaction to a 6,6,3-trimethylated substrate gave the product in only very low yield (9%), but with high enantioselectivity (90% ee; entry 3, Table 22) [48]. The application of the catalytic system in the addition reaction to an unsaturated lactone yielded the product with both low yield
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Published 10 May 2021

Progress in the total synthesis of inthomycins

  • Bidyut Kumar Senapati

Beilstein J. Org. Chem. 2021, 17, 58–82, doi:10.3762/bjoc.17.7

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  • ] cycloaddition reaction of an aldehyde and a ketene followed by their isomerization-free Stille coupling with (E)-5-(3-(tributylstannyl)allyl)oxazole (Schemes 8–10) [22]. In this synthesis, the enantiopure β-lactone (+)-79a was synthezised from (Z)-aldehyde 78 and propionyl chloride according to Nelson’s method
  • [53][54][55] using quinidine TMS ether (TMSQD), LiClO4, and Hünig’s base. The aldehyde (Z)-78 was obtained from propargyl alcohol 14 via (Z)-iodo alcohol 15a. The β-lactone (+)-79a was converted to enantioenriched vinyl iodides (+)-84 and 85a separately. Thus, methanolysis of (+)-79a provided (–)-80a
  • , and diisopropylethylamine in the presence of quinidine TMS ether (TMSQD) according to Nelson’s procedures [53][54][55] provided the enantioenriched β-lactone (−)-79b in 85% yield. The desired terminal acetylene (−)-82b was synthesized from β-lactone (−)-79b following a three-step sequence as shown in
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Published 07 Jan 2021

The fluorescence of a mercury probe based on osthol

  • Guangyan Luo,
  • Zhishu Zeng,
  • Lin Zhang,
  • Zhu Tao and
  • Qianjun Zhang

Beilstein J. Org. Chem. 2021, 17, 22–27, doi:10.3762/bjoc.17.3

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  • mode between OST and Hg2+ is suggested as shown in Figure 7. Hg2+ and the oxygen atoms of the lactone ring and the methoxy group formed a stable complex, resulting in the enhanced fluorescence. Isothermal titration calorimetry analysis A Hg2+ solution (2 × 10−3 mol∙L−1, 25 μL) was added to the 1 × 10−4
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Published 05 Jan 2021

All-carbon [3 + 2] cycloaddition in natural product synthesis

  • Zhuo Wang and
  • Junyang Liu

Beilstein J. Org. Chem. 2020, 16, 3015–3031, doi:10.3762/bjoc.16.251

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  • quaternary carbon stereocenters in 86% yield. Reduction of aldehyde 119 and subsequent transesterification produced a lactone (not shown). It was exposed to SeO2 to install the allylic hydroxy group to give 120 in 65% yield. Upon catalytic hydrogenation of 120, alcohol 121 was formed. This alcohol 120 was
  • produce 135 and 136 in 85% yield in the ratio of 1:1.16. A six-step synthesis from the major product 136 gave lactone 137. This compond was subjected to successive desilylation, OsO4-mediated dihydroxylation and subsequent oxidative cleavage of the C=C double bond with Pb(OAc)4 to give ketoaldehyde 138 in
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Published 09 Dec 2020

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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  • contained ithomiolide A (3), a pyrrolizidine alkaloid derived γ-lactone, I. s. derasa carried the sesquiterpene α-elemol (8) in the androconia. These differences might be important for the reproductive isolation of the two subspecies, in line with previously reported low gene exchange between the two
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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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  • yields. On the other hand, methylene-lactone-fused spirolactams could be delivered from the allyl adducts in high yields through a sequential N-Boc protection/desulfinative lactonization. Keywords: bifurcated synthesis; electrophilic amide allylation; α-methylene-γ-butyrolactam; α-methylene-γ
  • -lactone derivatives spiro-fused to an oxindole (A), one of which exhibited a potent cytotoxic activity [9]. Our research group succeeded the enantiopure synthesis of these compounds, in which enantioselective allylation of an isatin derivative with an amido-functionalized allylstannane was employed as a
  • reaction conditions and led to methylene-lactone-fused spirolactams 5a–h in excellent yields without exception (88–98% two-step yields). Thus, we established the bifurcated synthetic routes toward lactams spiro-fused to α-methylene-γ-butyrolactone or α-methylene-γ-butyrolactam by using 3-phenylthiolactams
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Published 13 Nov 2020

Nocarimidazoles C and D, antimicrobial alkanoylimidazoles from a coral-derived actinomycete Kocuria sp.: application of 1JC,H coupling constants for the unequivocal determination of substituted imidazoles and stereochemical diversity of anteisoalkyl chains in microbial metabolites

  • Md. Rokon Ul Karim,
  • Enjuro Harunari,
  • Amit Raj Sharma,
  • Naoya Oku,
  • Kazuaki Akasaka,
  • Daisuke Urabe,
  • Mada Triandala Sibero and
  • Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 2719–2727, doi:10.3762/bjoc.16.222

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  • actinomycete origin. For example, salinosporamide A, an antitumor drug candidate in clinical trials, is a proteasome inhibitor with an unusual γ-lactam-β-lactone bicyclic core produced by marine Salinospora tropica [10]. Abyssomicin, another example of uncommon polycyclic frameworks, is an antibacterial
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Published 05 Nov 2020

Synthesis of novel fluorinated building blocks via halofluorination and related reactions

  • Attila Márió Remete,
  • Tamás T. Novák,
  • Melinda Nonn,
  • Matti Haukka,
  • Ferenc Fülöp and
  • Loránd Kiss

Beilstein J. Org. Chem. 2020, 16, 2562–2575, doi:10.3762/bjoc.16.208

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  • the absence of the reagent. It is also worth mentioning that the bromolactone (rac)-17a was surprisingly stable against lactone ring-opening: the compound remained intact after 20 hours of reflux in methanol in the presence of a catalytic amount of H2SO4. Presumably, the halogen cation attacks from
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Published 16 Oct 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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Published 29 Sep 2020

Synthesis of 1,4-benzothiazinones from acylpyruvic acids or furan-2,3-diones and o-aminothiophenol

  • Ekaterina E. Stepanova,
  • Maksim V. Dmitriev and
  • Andrey N. Maslivets

Beilstein J. Org. Chem. 2020, 16, 2322–2331, doi:10.3762/bjoc.16.193

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  • 5a at the lactone carbonyl group, and the product 4a, when o-aminothiophenol’s NH2 group attacked compound 5a at the lactone carbonyl group. The in situ formation of 5-phenylfuran-2,3-dione (5a) was indicated by the appearance of bright yellow color (characteristic for the 5-arylfuran-2,3-diones 5 [6
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Published 21 Sep 2020

Photosensitized direct C–H fluorination and trifluoromethylation in organic synthesis

  • Shahboz Yakubov and
  • Joshua P. Barham

Beilstein J. Org. Chem. 2020, 16, 2151–2192, doi:10.3762/bjoc.16.183

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  • (+)-sclareolide (C2 and C3) are remote from the lactone EWG and both form secondary radicals. Thus, the fluorination of these positions is presumably dictated by hindrance, given that the C3 position is neighbored by a gem-dimethyl group and is fluorinated to a lesser extent (22%). In both reports, the C2/C3
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Published 03 Sep 2020

Syntheses of spliceostatins and thailanstatins: a review

  • William A. Donaldson

Beilstein J. Org. Chem. 2020, 16, 1991–2006, doi:10.3762/bjoc.16.166

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  • hydrogenation over Pt2O and then low-temperature DIBAL reduction afforded the all-cis tetrasubstituted tetrahydropyran 27. In Koide et al.’s synthesis, the unsaturated lactone 29 was prepared via the Wittig methenylation of 24, followed by aminal hydrolysis, methallylation of the 2° alcohol 28, and ring-closing
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Published 13 Aug 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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  • the corresponding acetate (4%, not shown), the bromomethyllactone 15 (8%), and alkene Z-13 (1%). Only lactone 14 could be isolated in a pure form (58% yield). The amount of HBr/AcOH had little influence on the selectivity (Table 4, entry 2) of the reaction. However, in the presence of TBAB (2.5 equiv
  • ) and CSA (2 equiv) an 84% conversion into mainly brominated lactone 15 (79%) with traces of hydroxylated lactone 14, and of bromoalkene Z-13 was determined by crude 19F NMR. The remaining 8% appeared to be the β-chloromethyllactone 19 (see Scheme 7 below), an analogue of 15 as determined by NMR
  • ). The former, using an excess of acid (33% HBr in AcOH solution) favored the direct nucleophilic attack (path b) leading to lactone 14, whereas the latter in the presence of TBAB/CSA allowed bromide addition on the same side of the fluorine atom (path a) leading to lactone 15 [31]. However, the reaction
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Published 07 Aug 2020

When metal-catalyzed C–H functionalization meets visible-light photocatalysis

  • Lucas Guillemard and
  • Joanna Wencel-Delord

Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147

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Published 21 Jul 2020

Clickable azide-functionalized bromoarylaldehydes – synthesis and photophysical characterization

  • Dominik Göbel,
  • Marius Friedrich,
  • Enno Lork and
  • Boris J. Nachtsheim

Beilstein J. Org. Chem. 2020, 16, 1683–1692, doi:10.3762/bjoc.16.139

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  • reduction with NaBH4 to give the primary alcohol 19. In contrast to benzaldehyde 7, carbaldehyde 18 showed no decomposition at ambient temperature. While acidic hydrolysis of 19 provided exocyclic γ-lactone 20, the substitution reaction with DPPA/NaN3 yielded the primary azide in 87% yield. In accordance to
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Published 14 Jul 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

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  • -substituted β-lactone products in a high yield, diastereo-, and enantioselectivity (Figure 2A) [46]. Chi and co-workers have reported limited examples of oxidative [2 + 2] cycloadditions using hydrocinnamaldehyde as an azolium enolate precursor and the NHC precatalyst 2, giving β-lactone products in high
  • -aroyloxyaldehyde 4 and trifluoromethylacetophenone (5) as reactants began using the NHC precatalyst 3, triethylamine as the base, and THF as the solvent (Table 1, entry 1). A moderate conversion (48%, as determined by NMR analysis) to the desired β-lactone product 6 as a 70:30 mixture of diastereoisomers was
  • , diethyl ether, and toluene showed no improvement upon the yield obtained with THF (Table 1, entries 4–6). Unfortunately, attempts to isolate the desired β-lactone product 6 were unsuccessful, with 6 being unstable to chromatographic purification under a variety of different conditions. As such, following
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Published 30 Jun 2020

Heterogeneous photocatalysis in flow chemical reactors

  • Christopher G. Thomson,
  • Ai-Lan Lee and
  • Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

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Published 26 Jun 2020

Recent synthesis of thietanes

  • Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

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Published 22 Jun 2020
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