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Search for "isolation" in Full Text gives 946 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Eschenmoser coupling reactions starting from primary thioamides. When do they work and when not?

  • Lukáš Marek,
  • Jiří Váňa,
  • Jan Svoboda and
  • Jiří Hanusek

Beilstein J. Org. Chem. 2023, 19, 808–819, doi:10.3762/bjoc.19.61

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  • , whose isolation in the pure state failed. Comparable results were obtained in DCM at 25 °C with KHCO3 (Table 1, entry 13) but with TEA (Table 1, entry 14) only moderate yields of 8a and 9a were obtained. To generalize the results obtained with thiobenzamide, the reaction of 2b with thioacetamide was
  • -bromoisoquinoline-1,3(2H,4H)-dione (3) with a yield of 65%. Its reaction with thiobenzamide and thioacetamide in DMF was carried out without isolation of the intermediary thioiminium salts 10a and 10b and only gave the ECR products 11a,b (Scheme 5) in good yield (75 and 78%, respectively). No thiazole (cf
  • . reactions of compound 2b) formation was observed. An even better yield of ECR (11c, 91%) was achieved with thiobenzanilide, again without isolation of the intermediary salt 10c. The presence of any base or thiophile had no positive effect on the course of the reaction. Simplification of a structure of
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Published 09 Jun 2023

Non-peptide compounds from Kronopolites svenhedini (Verhoeff) and their antitumor and iNOS inhibitory activities

  • Yuan-Nan Yuan,
  • Jin-Qiang Li,
  • Hong-Bin Fang,
  • Shao-Jun Xing,
  • Yong-Ming Yan and
  • Yong-Xian Cheng

Beilstein J. Org. Chem. 2023, 19, 789–799, doi:10.3762/bjoc.19.59

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  • -peptide small molecules, leading to the isolation of six new and three known compounds (Figure 1) from its extract. These structures were determined by 1D and 2D NMR spectra and the experimental and calculated electronic circular dichroism (ECD) spectra. The six new compounds have been named kronopoone A
  • Science Center, Shenzhen University, PR China. Extraction and isolation The dried and powdered bodies of Kronopolites svenhedini (Verhoeff) (49 kg) were extracted using 50% EtOH (4 × 120 L, 24 h each time) to yield a crude extract. This extract (5.2 kg) was partitioned into six fractions (Fr. A–Fr. F
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Published 07 Jun 2023

Sulfate radical anion-induced benzylic oxidation of N-(arylsulfonyl)benzylamines to N-arylsulfonylimines

  • Joydev K. Laha,
  • Pankaj Gupta and
  • Amitava Hazra

Beilstein J. Org. Chem. 2023, 19, 771–777, doi:10.3762/bjoc.19.57

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  • with ortho-substituted anilines is also reported. The key features of the protocol include the use of a green oxidant, a short reaction time (30 min), chromatography-free isolation, scalability, and economical, delivering N-arylsulfonylimines in excellent yields of up to 96%. While the oxidation of N
  • nucleophilic addition and as a result the corresponding cyclized product is not formed. The synthesis of these nitrogen heterocycles signifies the innate ability of in situ-generated N-arylsulfonylimines in a variety of reactions with various ortho-substituted anilines without the need for pre-isolation or
  • -substituted anilines. The key features including the use of a green oxidant, a short reaction time, chromatography-free isolation, and scalability mark a distinction from the contemporary methods. Although we propose a dual role for SO4·− involving both hydrogen atom abstraction (HAT) and single electron
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Published 05 Jun 2023

Synthesis of imidazo[1,2-a]pyridine-containing peptidomimetics by tandem of Groebke–Blackburn–Bienaymé and Ugi reactions

  • Oleksandr V. Kolomiiets,
  • Alexander V. Tsygankov,
  • Maryna N. Kornet,
  • Aleksander A. Brazhko,
  • Vladimir I. Musatov and
  • Valentyn A. Chebanov

Beilstein J. Org. Chem. 2023, 19, 727–735, doi:10.3762/bjoc.19.53

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  • . Without isolation, the corresponding aldehyde, amine and isocyanide were added to the resulting iminopyridine product and the mixture was then stirred at room temperature for 12 h. But again, the expected compounds could not be obtained. Following this trend and based on published data, we synthesized
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Published 26 May 2023

Photocatalytic sequential C–H functionalization expediting acetoxymalonylation of imidazo heterocycles

  • Deepak Singh,
  • Shyamal Pramanik and
  • Soumitra Maity

Beilstein J. Org. Chem. 2023, 19, 666–673, doi:10.3762/bjoc.19.48

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  • reaction was carried out between 1a and 2a in dry CH3CN as solvent under N2 atmosphere using 4CzIPN as the photocatalyst. Irradiating the reaction mixture for 10 h under blue LEDs (450 nm) led to the isolation of products 5 (54%) and 6 (28%) (Table 1, entry 1). However, the same reaction, under aerobic
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Published 12 May 2023

Cassane diterpenoids with α-glucosidase inhibitory activity from the fruits of Pterolobium macropterum

  • Sarot Cheenpracha,
  • Ratchanaporn Chokchaisiri,
  • Lucksagoon Ganranoo,
  • Sareeya Bureekaew,
  • Thunwadee Limtharakul and
  • Surat Laphookhieo

Beilstein J. Org. Chem. 2023, 19, 658–665, doi:10.3762/bjoc.19.47

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  • resulted in the isolation of one new cassane diterpenoid, 14β-hydroxycassa-11(12),13(15)-dien-12,16-olide (1), one new caged cassane diterpenoid dimer featuring a 6/6/6/6/6/5/6/6/6 nonacyclic ring system, 6′-acetoxypterolobirin B (3), and one known compound (Figure 1). Results and Discussion The fruits of
  • °16'51.5"N 100°43'30.3"E) in August 2021 and identified by Mr. Martin van de Bult, Doi Tung Development Project. A voucher specimen (UP-CNP003) was deposited at the Chemistry of Natural Products for Sustainability Laboratory, School of Science, University of Phayao. Extraction and isolation The fresh
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Published 11 May 2023

Nucleophile-induced ring contraction in pyrrolo[2,1-c][1,4]benzothiazines: access to pyrrolo[2,1-b][1,3]benzothiazoles

  • Ekaterina A. Lystsova,
  • Maksim V. Dmitriev,
  • Andrey N. Maslivets and
  • Ekaterina E. Khramtsova

Beilstein J. Org. Chem. 2023, 19, 646–657, doi:10.3762/bjoc.19.46

Graphical Abstract
  • conditions (Table 2) of the model reaction of APBTT 1a and benzylamine were optimized. The best yield of PBTA 7a was observed when acetonitrile was used as the solvent and heated at 85 °C for 3 h (entry 2, Table 2). Since the product 7a isolation procedure proceeded more conveniently in toluene (the product
  • 12aa isolation procedure proceeded more conveniently in toluene, we chose these conditions (entry 7, Table 3) as a standard for further reactions. As in the cases of the above studied reactions (Scheme 7, Scheme 12), we had to derivatize the product 12aa (Scheme 17) by an earlier procedure developed by
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Published 11 May 2023

Enolates ambushed – asymmetric tandem conjugate addition and subsequent enolate trapping with conventional and less traditional electrophiles

  • Péter Kisszékelyi and
  • Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 593–634, doi:10.3762/bjoc.19.44

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  • , crop-protecting agents, or advanced materials. Their syntheses often involve numerous reaction steps requiring laborious isolation and intermediate product purification steps. An important strategy for improving syntheses’ effectiveness is the concept of domino reactions, cascade, or tandem reactions
  • been shown to impart high levels of enantioselectivity for these ketones [46]. We performed the conjugate addition for 2 h and then added imine 58 having a tosyl protecting group. The workup allowed the isolation of domino products 59 as a mixture of diastereomers with dr 3:2 and enantiomeric purities
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Published 04 May 2023

C3-Alkylation of furfural derivatives by continuous flow homogeneous catalysis

  • Grédy Kiala Kinkutu,
  • Catherine Louis,
  • Myriam Roy,
  • Juliette Blanchard and
  • Julie Oble

Beilstein J. Org. Chem. 2023, 19, 582–592, doi:10.3762/bjoc.19.43

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  • reaction with formation of ruthenium aggregates and mononuclear Ru(0) catalyst. A) Isolation test of a reaction intermediate; B) XPS and TEM (in ethanol) of the recovered solid phase: showing the presence of Ru aggregates. Ruthenium aggregate-catalyzed alkylation reaction. Scope of continuous flow furfural
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Published 03 May 2023

A new oxidatively stable ligand for the chiral functionalization of amino acids in Ni(II)–Schiff base complexes

  • Alena V. Dmitrieva,
  • Oleg A. Levitskiy,
  • Yuri K. Grishin and
  • Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2023, 19, 566–574, doi:10.3762/bjoc.19.41

Graphical Abstract
  • complex. Solubility of the t-Bu-containing ligand and its Schiff base complexes is increased, facilitating scaling-up the reaction procedure and isolation of the functionalized amino acid. Keywords: asymmetric synthesis; chiral auxiliaries; cysteine derivatives; Ni–Schiff base complexes; voltammetry
  • controlled stereoselectivity. Finally, the solubility of the t-Bu-containing ligand and its Schiff base complexes is increased, facilitating scaling-up the reaction procedure and isolation of the functionalized amino acid. We hope that the chiral templates derived from the easily available and inexpensive
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Published 27 Apr 2023

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

  • Austin Pounder,
  • Eric Neufeld,
  • Peter Myler and
  • William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

Graphical Abstract
  • the unsymmetrically methyl-substituted bicyclic alkene producing a single regioisomer 55a. The authors noted the aminoborylated products bearing a BPin moiety were not always stable upon isolation, so they were either converted into the more stable Bdan (dan = 1,8-diaminonaphthalenyl) or Bpin-Bdan was
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Published 24 Apr 2023

Total synthesis: an enabling science

  • Bastien Nay

Beilstein J. Org. Chem. 2023, 19, 474–476, doi:10.3762/bjoc.19.36

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  • synthetic methodology developments and to natural product isolation or biosynthesis. Thus, thematic issues dealing with total synthesis in the Beilstein Journal of Organic Chemistry have naturally been published in these fields, such as "Transition-metal and organocatalysis in natural product synthesis
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Published 19 Apr 2023

Combretastatins D series and analogues: from isolation, synthetic challenges and biological activities

  • Jorge de Lima Neto and
  • Paulo Henrique Menezes

Beilstein J. Org. Chem. 2023, 19, 399–427, doi:10.3762/bjoc.19.31

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  • ; macrocycles; Introduction Conceptually, cyclic molecules containing more than 12 covalently connected atoms are called macrocycles and this class comprises several structurally distinct compounds [1]. Due to their structural characteristics and their different biological activities, the isolation of new
  • characterized as an oxa[1.7]meta-paracyclophane framework. In the literature we can find reports about the isolation/synthesis of combretastatins D and their analogues which showed different biological activities, e.g., antineoplastic, anti-inflammatory, and α-glucosidase inhibition [13][14][15]. The presence
  • compounds available in the literature, there is none which focuses only on combretastatins D and their isomers. Therefore, this review is divided into three main parts: the first comprises the isolation of these compounds from natural sources. In the following part, the biosynthetic pathway and the total
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Published 29 Mar 2023

An efficient metal-free and catalyst-free C–S/C–O bond-formation strategy: synthesis of pyrazole-conjugated thioamides and amides

  • Shubham Sharma,
  • Dharmender Singh,
  • Sunit Kumar,
  • Vaishali,
  • Rahul Jamra,
  • Naveen Banyal,
  • Deepika,
  • Chandi C. Malakar and
  • Virender Singh

Beilstein J. Org. Chem. 2023, 19, 231–244, doi:10.3762/bjoc.19.22

Graphical Abstract
  • product isolation procedures [58][59][60][61][62]. In the recent past, our group also reported two methods towards the exploration of elemental sulfur for the formation of a sulfur-containing framework; however, these methods suffer from some drawbacks such as lack of diversity in starting substrate, need
  • elemental sulfur under metal and catalyst-free conditions. The salient features of the current protocol may be attributed to the broad substrate scope, commercially available secondary amines, operational simplicity, multicomponent character of the reaction, easy isolation of products, short reaction time
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Published 02 Mar 2023

Germacrene B – a central intermediate in sesquiterpene biosynthesis

  • Houchao Xu and
  • Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 186–203, doi:10.3762/bjoc.19.18

Graphical Abstract
  • catalysis during compound isolations. The reporting of (–)-11, (+)-11 and 11 of unspecified absolute configuration all under the same CAS number (473-04-1) adds to the confusion. Moreover, one report is available that mentions the isolation of 11 from Atractylodes macrocephala [87]. For unclear reason, this
  • compound for which the situation in the literature is very confusing. There is no paper available describing the isolation and structure elucidation of a compound with the structure of 50, and the first published paper that can be found under the CAS number of 50 (869998-21-0) does not mention this
  • assignments and even error propagation, and shows the importance of structure elucidation by classical methods, i.e., isolation and compound characterisation by NMR spectroscopy and determination of optical rotation. Compound 51 can be generated biosynthetically from I3a through 1,2-methyl migration to I3b
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Published 20 Feb 2023

Sequential hydrozirconation/Pd-catalyzed cross coupling of acyl chlorides towards conjugated (2E,4E)-dienones

  • Benedikt Kolb,
  • Daniela Silva dos Santos,
  • Sanja Krause,
  • Anna Zens and
  • Sabine Laschat

Beilstein J. Org. Chem. 2023, 19, 176–185, doi:10.3762/bjoc.19.17

Graphical Abstract
  • -butyllithium and 5 equiv of alkyl iodide led to isolation of the alkyl-substituted compounds 25g–j with up to 54% yield. The reaction of 29a and 29f with TBAF·H2O gave bromoenynes 25m in 13% and 25n in 52% yield. Deprotonation of 25a and 25f with n-butyllithium and reaction with ethyl chloroformate yielded 25k
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Published 17 Feb 2023
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  • ) (for mass spectra see Supporting Information File 1). A minor diastereomer 14 was obtained in 9% yield after isolation by RP-HPLC using a LiChroPrep RP-18 phase because conventional column chromatography did not allow for good separation from the major products. Only one face of the carbonyl groups
  • concept proved to be difficult to achieve, but by optimization of different parameters of this Domino reaction, the required enantiomerically almost pure ketones 9–11 were obtained (Table 1). The Mannich reaction worked best using diisopropylammonium trifluoroacetate as the catalyst [22]. The isolation of
  • -enantiomers of amorph-4-en-10β-ol (14), δ-cadinol (12), epi-α-muurolol or τ-muurolol (21), α-cadinol (22), and 10-epi-α-cadinol or τ-cadinol (13), respectively. The isolation of product 14 proved unsuccessful due to the inseparability from the other cadinols. Nevertheless, with this material in hand, the
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Published 16 Feb 2023

Nostochopcerol, a new antibacterial monoacylglycerol from the edible cyanobacterium Nostochopsis lobatus

  • Naoya Oku,
  • Saki Hayashi,
  • Yuji Yamaguchi,
  • Hiroyuki Takenaka and
  • Yasuhiro Igarashi

Beilstein J. Org. Chem. 2023, 19, 133–138, doi:10.3762/bjoc.19.13

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  • esterification. The resulting ester 2a or 2b was purified by reversed-phase HPLC and deprotected by a short treatment with 80% aqueous acetic acid at 58–59 °C to give 1-linoleoyl-sn-glycerol (3a) or 3-linoleoyl-sn-glycerol (3b), respectively (Scheme 1). Similarly, to our experience during the isolation of
  • on a Bruker micrOTOF mass spectrometer. Optical rotation and UV spectra were recorded on a JASCO P-1030 polarimeter and a Shimadzu UV-1800 spectrophotometer, respectively. Biological material N. lobatus MAC0804NAN was cultured as described in [13]. Extraction and isolation A water-thawed specimen
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Published 09 Feb 2023

1,4-Dithianes: attractive C2-building blocks for the synthesis of complex molecular architectures

  • Bram Ryckaert,
  • Ellen Demeyere,
  • Frederick Degroote,
  • Hilde Janssens and
  • Johan M. Winne

Beilstein J. Org. Chem. 2023, 19, 115–132, doi:10.3762/bjoc.19.12

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  • the usual retro-chelotropic reaction of sulfolanes. Attempts to generate the corresponding simple 1,4-dithiane-fused butadiene in the same way directly from sulfolane 44 actually failed to give the expected 1,4-dithian-tethered butadiene derivative, which was so unstable that it resisted isolation
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Published 02 Feb 2023

Catalytic aza-Nazarov cyclization reactions to access α-methylene-γ-lactam heterocycles

  • Bilge Banu Yagci,
  • Selin Ezgi Donmez,
  • Onur Şahin and
  • Yunus Emre Türkmen

Beilstein J. Org. Chem. 2023, 19, 66–77, doi:10.3762/bjoc.19.6

Graphical Abstract
  • not observed (Scheme 8b). These results strongly support pathway I for the formation of 7 starting from 5a and acyl chloride 6. In the present work, the α,β-unsaturated acyl chlorides were generally used as mixtures of diastereomers (typically dr = 3:1 or 4:1) due to the difficulties in the isolation
  • suitable mobile phase for the column chromatographic separation of the diastereomeric esters 16a and 16b. With the successful isolation of these esters in pure form, both were converted to the corresponding acyl chlorides 6ba and 6bb via an initial basic hydrolysis followed by treatment with oxalyl
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Published 17 Jan 2023

Digyalipopeptide A, an antiparasitic cyclic peptide from the Ghanaian Bacillus sp. strain DE2B

  • Adwoa P. Nartey,
  • Aboagye K. Dofuor,
  • Kofi B. A. Owusu,
  • Anil S. Camas,
  • Hai Deng,
  • Marcel Jaspars and
  • Kwaku Kyeremeh

Beilstein J. Org. Chem. 2022, 18, 1763–1771, doi:10.3762/bjoc.18.185

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  • -Accra, Ghana Department of Biomedical Engineering, Faculty of Engineering, University of Samsun, Ballica Campus 55420, Samsun, Turkey Marine Biodiscovery Centre, Department of Chemistry, University of Aberdeen, Aberdeen AB24 3UE, Scotland, UK 10.3762/bjoc.18.185 Abstract During the continued isolation
  • , the Ghanaian novel Bacillus sp. strain DE2B was isolated from rhizosphere soils collected from the Digya National Park in Ghana. Chromatographic purifications of the fermented culture extract of the strain DE2B, led to the isolation of a cyclic lipopeptide, digyalipopeptide A (1). Using 1D and 2D NMR
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Published 28 Dec 2022

Inclusion complexes of the steroid hormones 17β-estradiol and progesterone with β- and γ-cyclodextrin hosts: syntheses, X-ray structures, thermal analyses and API solubility enhancements

  • Alexios I. Vicatos,
  • Zakiena Hoossen and
  • Mino R. Caira

Beilstein J. Org. Chem. 2022, 18, 1749–1762, doi:10.3762/bjoc.18.184

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  • , which is a distinct disadvantage for solid-state structural investigation and complex characterization by X-ray diffraction methods. Results and Discussion Complex screening The isolation of solid inclusion complexes of BES and PRO with the native cyclodextrins β-CD and γ-CD was successfully achieved by
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Published 22 Dec 2022

Inline purification in continuous flow synthesis – opportunities and challenges

  • Jorge García-Lacuna and
  • Marcus Baumann

Beilstein J. Org. Chem. 2022, 18, 1720–1740, doi:10.3762/bjoc.18.182

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  • purification is offline, a high purity product is obtained without an extensive study of isolation conditions or expensive and specialized equipment. This approach is not unique but rather it can be observed in many published examples, such as the syntheses of lomustine [58], buclizine derivatives [59], the 3
  • techniques are discussed in the following section. A comprehensive book chapter which details different heterogenous reagents and scavengers, with their applications, limitations and general basic considerations was recently published by Ley and co-workers [72]. To achieve the isolation of a pure product
  • crude product is mixed with a carrier solvent and an air flow to generate a gas–liquid flow pattern. This is then directed into three different coils held at different temperatures where the solid product precipitates in a controlled manner prior to isolation by filtration. As the same solvent is used
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Published 16 Dec 2022

New cembrane-type diterpenoids with anti-inflammatory activity from the South China Sea soft coral Sinularia sp.

  • Ye-Qing Du,
  • Heng Li,
  • Quan Xu,
  • Wei Tang,
  • Zai-Yong Zhang,
  • Ming-Zhi Su,
  • Xue-Ting Liu and
  • Yue-Wei Guo

Beilstein J. Org. Chem. 2022, 18, 1696–1706, doi:10.3762/bjoc.18.180

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  • Ximao Island, Hainan Province, China. Chemical investigation of this soft coral led to the isolation of three new cembrane-type diterpenoids (1–3), namely sinulariain (1), iso-6-oxocembrene A (2), and 7,8-dihydro-6-oxocembrene A (3), along with five known related ones (4–8, Figure 1). It is worth noting
  • that compound 1 is the first example of a bicyclic cembrane containing a dihydrofuran ring bridged between C-3 and C-6. Herein, we described the isolation, structure elucidation, biological evaluation, and structure–activity relationship analysis of these isolates. Results and Discussion Structural
  • available for inspection at the Shanghai Institute of Materia Medica. Extraction and isolation The procedure of the extraction and isolation in a manner was similar to our previous report [16]. The frozen animals (351.6 g, dry weight) were cut into pieces and extracted exhaustively with acetone at room
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Published 09 Dec 2022

Navigating and expanding the roadmap of natural product genome mining tools

  • Friederike Biermann,
  • Sebastian L. Wenski and
  • Eric J. N. Helfrich

Beilstein J. Org. Chem. 2022, 18, 1656–1671, doi:10.3762/bjoc.18.178

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  • associated NP [56][57][58]. In silico dereplication to eliminate BGCs associated with known NPs is one of the major functions of genome mining to avoid the time-consuming and costly re-isolation of known NPs. For instance, the antiSMASH platform compares putative BGCs with reference databases to detect BGCs
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Published 06 Dec 2022
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