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Search for "adduct" in Full Text gives 582 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Selective and reversible 1,3-dipolar cycloaddition of 6-aryl-1,5-diazabicyclo[3.1.0]hexanes with 1,3-diphenylprop-2-en-1-ones under microwave irradiation

  • Alexander P. Molchanov,
  • Mariia M. Efremova,
  • Mariya A. Kryukova and
  • Mikhail A. Kuznetsov

Beilstein J. Org. Chem. 2020, 16, 2679–2686, doi:10.3762/bjoc.16.218

Graphical Abstract
  • polar species in the ionic medium. Therefore, we carried out the reaction of DABCH 1a with propenone 2f in bmimCl in the presence of BF3·Et2O at 80 °C for 8 h, that led to the formation of adduct 3m and pyrazoline 4a. The reaction of DABCH 1b and propenone 2a under the same conditions resulted in the
  • formation of adduct 3m and pyrazoline 4b (Scheme 3). Thus, the azomethine imine A, formed by heating of DABCH 1a, either reacts with propenone 2f giving the adduct 3m or undergoes isomerization affording pyrazoline 4a. On the basis of this observation we suppose that the reaction products undergo
  • cycloreversion, i.e., under the reaction conditions the adduct 3m may undergo a ring-opening with the liberation of the starting propenone 2f and the new isomeric azomethine imine B. The latter is able to isomerize into pyrazoline 4b or it reacts with propenone 2f leading to adduct 3f (Scheme 4). To prove this
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Published 30 Oct 2020

Water-soluble host–guest complexes between fullerenes and a sugar-functionalized tribenzotriquinacene assembling to microspheres

  • Si-Yuan Liu,
  • Xin-Rui Wang,
  • Man-Ping Li,
  • Wen-Rong Xu and
  • Dietmar Kuck

Beilstein J. Org. Chem. 2020, 16, 2551–2561, doi:10.3762/bjoc.16.207

Graphical Abstract
  • ppm in the 13C NMR spectrum were attributed to the acetylene protons and carbons, respectively. The electrospray ionization (ESI) mass spectrum showed the most intense peak at m/z 641.1923, which corresponds to the [M + Na]+ molecular adduct ion and matches well with the calculated value (m/z 641.1935
  • -hydroxycinnamic acid (CHCA) as a matrix, exhibits the base peak at m/z 2879 along with an adjacent intense peak at m/z 2896, which are assigned to the [M + Na]+ and [M + K]+ molecular adduct ions, respectively. Unfortunately, attempts to perform accurate mass measurements were unsuccessful. However, the MALDI
  • peak group with the maximum component at m/z 1505.9690 and Δ(m/z) = 0.5, indicating the presence of doubly charged ions. The most intense peak is assigned to the doubly charged [M + 1] isotopolog of the molecular adduct [M + 6H2O + 2Na]2+, the theoretical value of which is calculated to be m/z
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Published 14 Oct 2020

Computational tools for drawing, building and displaying carbohydrates: a visual guide

  • Kanhaya Lal,
  • Rafael Bermeo and
  • Serge Perez

Beilstein J. Org. Chem. 2020, 16, 2448–2468, doi:10.3762/bjoc.16.199

Graphical Abstract
  • tool has been particularly upgraded for MS spectrum annotation by adding an intuitive interface with additional features. The upgraded version can depict bond fragmentation, repeating structural unit anomeric groups, adduct ions, different types of glycosidic linkages etc. These advanced features make
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Published 02 Oct 2020

Formation of an exceptionally stable ketene during phototransformations of bicyclo[2.2.2]oct-5-en-2-ones having mixed chromophores

  • Asitanga Ghosh

Beilstein J. Org. Chem. 2020, 16, 2297–2303, doi:10.3762/bjoc.16.190

Graphical Abstract
  • ][18] and dibenzoyl acetylene (9) followed by hydrolysis of the silyloxy adduct (Scheme 4). Both 7a and 7b showed an enhanced (n,π*) absorption band near 300 nm (log ε ≈ 3.5) along with an additional weak band near 343 nm (log ε ≈ 2.5) in their UV spectra as expected for δ-keto-α,β-enone [7
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Published 15 Sep 2020

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

  • Shakeel Alvi and
  • Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

Graphical Abstract
  • sumanene provided the covalent adduct 171 with Cl atoms attached onto the Te atoms, confirmed by an X-ray analysis (Scheme 44). Having the quinone derivatives 166 and 167 in hands, they were next subjected to the condensation reaction with a variety of aryl-1,2-diamines 168 in the presence of AcOH to
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Published 09 Sep 2020

Reactions of 3-aryl-1-(trifluoromethyl)prop-2-yn-1-iminium salts with 1,3-dienes and styrenes

  • Thomas Schneider,
  • Michael Keim,
  • Bianca Seitz and
  • Gerhard Maas

Beilstein J. Org. Chem. 2020, 16, 2064–2072, doi:10.3762/bjoc.16.173

Graphical Abstract
  • –Alder reaction of 1-CF3-substituted propyn-1-iminium salt 1a with cyclopentadiene was carried out in order to assess the dienophilic reactivity of the cation. High conversion into cycloaddition product 2 was observed already within one hour at 0 °C. Because of its high hydrolytic lability, adduct 2 was
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Published 24 Aug 2020

Controlling the stereochemistry in 2-oxo-aldehyde-derived Ugi adducts through the cinchona alkaloid-promoted electrophilic fluorination

  • Yuqing Wang,
  • Gaigai Wang,
  • Anatoly A. Peshkov,
  • Ruwei Yao,
  • Muhammad Hasan,
  • Manzoor Zaman,
  • Chao Liu,
  • Stepan Kashtanov,
  • Olga P. Pereshivko and
  • Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2020, 16, 1963–1973, doi:10.3762/bjoc.16.163

Graphical Abstract
  • dichloromethane results in the assembly of an α-acyloxyamide adduct 4. Just a few protocols for the asymmetric P-3CR [37][38][39][40] and its modifications [41][42][43][44][45][46][47] have been reported over the course of the last two decades (Table 1). In the majority of those protocols [37][38][39], the
  • -component reaction (U-4CR) a carboxylic acid 1, an aldehyde 2, and an isocyanide 3 are complemented by a primary amine 5 that altogether undergo a condensation into a peptide-like adduct 6. These reactions are typically conducted in polar protic solvents such as methanol or water. Several examples of
  • , a cinchona alkaloid derivative was allowed to react with an electrophilic fluorinating agent to afford an N-fluoroammonium salt of the cinchona alkaloid via transfer fluorination. In the second step, the Ugi adduct 8a was added to this in situ generated N-fluorocinchona intermediate to afford the
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Published 11 Aug 2020

Regiodivergent synthesis of functionalized pyrimidines and imidazoles through phenacyl azides in deep eutectic solvents

  • Paola Vitale,
  • Luciana Cicco,
  • Ilaria Cellamare,
  • Filippo M. Perna,
  • Antonio Salomone and
  • Vito Capriati

Beilstein J. Org. Chem. 2020, 16, 1915–1923, doi:10.3762/bjoc.16.158

Graphical Abstract
  • at 50 °C, we were able to isolate by column chromatography on silica gel a product which was characterized as 2-benzoyl-(4 or 5)-phenyl-(1H)-imidazole (3a/3a', Scheme 2). This adduct was formed as a mixture of two tautomers (3a and 3a'; 3a/3a' ratio: 57:43, Supporting Information File 1) [28][29] in
  • the para-position delivered the expected adduct 3k/3k' in 32% yield even by prolonging the reaction time to 16 h, most probably because of the poor solubility in the eutectic mixture and/or the higher thermal stability towards the loss of N2 (vide infra) of the corresponding phenacyl azide 2k as it is
  • -azide 4a, would undergo either dimerization to give 6a, and then imidazoles 3a/3a' after cyclization and dehydration (see Scheme 5), or trimerization to afford adduct 8a further to an additional attack of 5a to the internal imino group of 6a and dehydration. Consecutive tautomerization, followed by an
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Published 05 Aug 2020

Pauson–Khand reaction of fluorinated compounds

  • Jorge Escorihuela,
  • Daniel M. Sedgwick,
  • Alberto Llobat,
  • Mercedes Medio-Simón,
  • Pablo Barrio and
  • Santos Fustero

Beilstein J. Org. Chem. 2020, 16, 1662–1682, doi:10.3762/bjoc.16.138

Graphical Abstract
  • this sense, while the addition of hard organometallic nucleophiles, such as lithium dialkylcuprates or Grignard reagents, failed, softer nucleophiles such as nitroalkanes cleanly added to the β-position, providing the Michael adduct 61. Unexpectedly, the conjugate addition reaction resulted in
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Published 14 Jul 2020

Azidophosphonium salt-directed chemoselective synthesis of (E)/(Z)-cinnamyl-1H-triazoles and regiospecific access to bromomethylcoumarins from Morita–Baylis–Hillman adducts

  • Soundararajan Karthikeyan,
  • Radha Krishnan Shobana,
  • Kamarajapurathu Raju Subimol,
  • J. Helen Ratna Monica and
  • Ayyanoth Karthik Krishna Kumar

Beilstein J. Org. Chem. 2020, 16, 1579–1587, doi:10.3762/bjoc.16.130

Graphical Abstract
  • the MBH adduct 1a (1 equiv) and propargyl alcohol (2a, 1.2 equiv) in presence of the AzPS [Ph3P+CBr3]N3− (see Supporting Information File 1 for the substituent patterns of the compounds 1a–o). In this precedent reaction, the adduct 1a and propargyl alcohol (2a) in THF were treated with the AzPS (1
  • derivatives 3a–d/g–k/m–q in a yield of 70–88%. Distinctively, the cyano acrylate-substituted MBH adduct stereoselectively afforded the (Z)-cinnamyl-1,4-disubstituted 1,2,3-triazole derivatives 3e/f/l in a yield of 82–92%. Irrespective of the acetylene moiety, the MBH adducts derived from acrylonitrile
  • attack on the AzPS by the allylic alcohol of the MBH adduct Ia. Subsequently, the azide ion undergoes a nucleophilic attack on the allylic carbon atom of the oxyphosphonium intermediate IIa and generates the 2-azidoalkene IIIa. Interestingly, the consecutive nucleophilic attack by the azido ion smoothly
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Published 01 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

Graphical Abstract
  • precatalyst 3 [58], reversible addition of the free NHC I to the aldehyde leads to adduct II [59]. A subsequent deprotonation allows access to Breslow intermediate III, which can eliminate para-nitrobenzoate to leave azolium enol IV. Deprotonation gives azolium enolate intermediate V, which undergoes a formal
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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

4-Hydroxy-3-methyl-2(1H)-quinolone, originally discovered from a Brassicaceae plant, produced by a soil bacterium of the genus Burkholderia sp.: determination of a preferred tautomer and antioxidant activity

  • Dandan Li,
  • Naoya Oku,
  • Yukiko Shinozaki,
  • Yoichi Kurokawa and
  • Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 1489–1494, doi:10.3762/bjoc.16.124

Graphical Abstract
  • (5.2 mg) with sufficient purity for structure characterization. The molecular formula of 1 was determined to be C10H9NO2 based on a sodium adduct molecular ion peak at m/z 198.0525 observed by a HRESITOFMS measurement (calcd 198.0526). The broad IR absorption band around 3100 cm−1 and an intense peak
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Published 26 Jun 2020

One-pot synthesis of 1,3,5-triazine-2,4-dithione derivatives via three-component reactions

  • Gui-Feng Kang and
  • Gang Zhang

Beilstein J. Org. Chem. 2020, 16, 1447–1455, doi:10.3762/bjoc.16.120

Graphical Abstract
  • nucleophilic addition of another molecule 2 takes place to furnish the tricomponent adduct 4, which undergoes elimination of ammonia to afford the corresponding ring-closed intermediate 7 [37]. The latter undergoes a proton-transfer process to form intermediate 10 [38]. Thereafter, the subsequent step involves
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Published 24 Jun 2020

Highly selective Diels–Alder and Heck arylation reactions in a divergent synthesis of isoindolo- and pyrrolo-fused polycyclic indoles from 2-formylpyrrole

  • Carlos H. Escalante,
  • Eder I. Martínez-Mora,
  • Carlos Espinoza-Hicks,
  • Alejandro A. Camacho-Dávila,
  • Fernando R. Ramos-Morales,
  • Francisco Delgado and
  • Joaquín Tamariz

Beilstein J. Org. Chem. 2020, 16, 1320–1334, doi:10.3762/bjoc.16.113

Graphical Abstract
  • ) [58][59][65]. Regarding the addition of diene 8c with the N-methylmaleimide (7b), a π···π interaction is discarded. Nevertheless, the endo adduct 9g was obtained as the major diastereoisomer (Table 2, entry 7). The calculated geometry at the endo TS reveals a plausible Cmethyl–H···π interaction, based
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Published 17 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

Graphical Abstract
  • , respectively (Scheme 48) [137]. Presumably, the C-centered radical formed after 5-exo-trig cyclization of the oxime radical recombines with TEMPO. The resulting adduct undergoes β-elimination of TEMPOH with the formation of final unsaturated compounds. The intermediate coupling product of the C-centered
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Published 05 Jun 2020

Synthesis of pyrrolidinedione-fused hexahydropyrrolo[2,1-a]isoquinolines via three-component [3 + 2] cycloaddition followed by one-pot N-allylation and intramolecular Heck reactions

  • Xiaoming Ma,
  • Suzhi Meng,
  • Xiaofeng Zhang,
  • Qiang Zhang,
  • Shenghu Yan,
  • Yue Zhang and
  • Wei Zhang

Beilstein J. Org. Chem. 2020, 16, 1225–1233, doi:10.3762/bjoc.16.106

Graphical Abstract
  • with 2-bromobenzaldehydes 3 and maleimides 4 (Scheme 3) [30][37]. The cycloaddition reactions were diastereoselective (>20:1 dr for adducts 5 and >6:1 dr for adducts 6). The major diastereomers of 5 and 6 were isolated for following N-allylation and intramolecular Heck reactions. Adduct 5a generated
  • ester 1 (1.2 mmol), 2-bromobenzaldehyde 3 (1 mmol) and maleimide 4 (1.1 mmol) in EtOH (3 mL) with Et3N (1.5 mmol) was heated at 110 °C for 6 h in a sealed vial. The concentrated reaction mixture was isolated by column chromatography on silica gel to afford adduct 5 in 85–90% yield. General procedure for
  • on silica gel to afford adduct 6 in 75–85% yield. General procedure for the synthesis of pyrrolo[2,1-a]isoquinolines 9 or 11 To a solution of pyrrolidine adduct 5 or 6 (0.5 mmol), 3-bromopropene (7, 1.5 mmol) in MeCN (3 mL) was added K2CO3 (1 mmol), the mixture was heated at 105 °C for 4 h in a
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Published 04 Jun 2020

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

  • Stephanie G. E. Amos,
  • Marion Garreau,
  • Luca Buzzetti and
  • Jerome Waser

Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103

Graphical Abstract
  • transformation, the arene is first oxidized by the excited state of the photocatalyst, generating the arene radical cation I. The latter then undergoes a nucleophilic attack of the N-heterocycle, affording the radical adduct II. TEMPO and O2 act as oxidants for the formation of the final aromatic compound via
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Published 29 May 2020

The charge-assisted hydrogen-bonded organic framework (CAHOF) self-assembled from the conjugated acid of tetrakis(4-aminophenyl)methane and 2,6-naphthalenedisulfonate as a new class of recyclable Brønsted acid catalysts

  • Svetlana A. Kuznetsova,
  • Alexander S. Gak,
  • Yulia V. Nelyubina,
  • Vladimir A. Larionov,
  • Han Li,
  • Michael North,
  • Vladimir P. Zhereb,
  • Alexander F. Smol'yakov,
  • Artem O. Dmitrienko,
  • Michael G. Medvedev,
  • Igor S. Gerasimov,
  • Ashot S. Saghyan and
  • Yuri N. Belokon

Beilstein J. Org. Chem. 2020, 16, 1124–1134, doi:10.3762/bjoc.16.99

Graphical Abstract
  • under the same conditions in the absence of F-1 produced the Diels–Alder adduct in a yield of just 10%. Conclusion In summary, by utilizing the acid–base neutralization reaction between two equivalents of NDS and one equivalent of the tetrahydrochloride salt of TAPM in water, a novel three-dimensional
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Published 26 May 2020

Copper catalysis with redox-active ligands

  • Agnideep Das,
  • Yufeng Ren,
  • Cheriehan Hessin and
  • Marine Desage-El Murr

Beilstein J. Org. Chem. 2020, 16, 858–870, doi:10.3762/bjoc.16.77

Graphical Abstract
  • % catalyst loading, bhomo-coupling adduct. Access to 1,2-oxy-aminoarenes by copper-catalyzed phenol–amine coupling. Copper-catalyzed aziridination through molecular spin catalysis with redox-active iminosemiquinone ligands. Nitrogen-group and carbon-group transfer in copper-catalyzed aziridination and
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Published 24 Apr 2020

Reaction of indoles with aromatic fluoromethyl ketones: an efficient synthesis of trifluoromethyl(indolyl)phenylmethanols using K2CO3/n-Bu4PBr in water

  • Thanigaimalai Pillaiyar,
  • Masoud Sedaghati and
  • Gregor Schnakenburg

Beilstein J. Org. Chem. 2020, 16, 778–790, doi:10.3762/bjoc.16.71

Graphical Abstract
  • makes a hydrogen bond interaction with the NH of the 5-methoxyindole (1a) and form the adduct B. This interaction assists 1a reacting with an electrophilic ketone (2a) to form the intermediate D via C–C bond formation (C). Re-aromatization of D generates E, which then protonates to form the desired
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Published 20 Apr 2020

Combining enyne metathesis with long-established organic transformations: a powerful strategy for the sustainable synthesis of bioactive molecules

  • Valerian Dragutan,
  • Ileana Dragutan,
  • Albert Demonceau and
  • Lionel Delaude

Beilstein J. Org. Chem. 2020, 16, 738–755, doi:10.3762/bjoc.16.68

Graphical Abstract
  • reaction generated the syn aldol adduct, having the steric configuration imposed in des-epoxy-amphidinolide N. Also, in the last step of their work, Trost et al. managed to install the C14-OH via a finely tuned Rubottom oxidation that finalized the total synthesis of des-epoxy-amphidinolide N. Strikingly
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Published 16 Apr 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

Graphical Abstract
  • at room temperature. The initial homopropargylic borane adduct, upon oxidation with NaBO3·H2O, yields the desired nonracemic tertiary alcohols 371–373 in typically high chemical yields, good diastereoselectivities, and impressive enantioselectivities. The subsequent treatment of these newly formed
  • resulted in 99% of the borylated product 414, which may indicate the presence of a radical intermediate in the second, protodeboronation step. Therefore, the key intermediate is the 1,4-adduct 415, which in the presence of base and water affords the saturated product (e.g., 410, 411; Scheme 66) [129]. The
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Published 15 Apr 2020

Microwave-assisted efficient and facile synthesis of tetramic acid derivatives via a one-pot post-Ugi cascade reaction

  • Yong Li,
  • Zheng Huang,
  • Jia Xu,
  • Yong Ding,
  • Dian-Yong Tang,
  • Jie Lei,
  • Hong-yu Li,
  • Zhong-Zhu Chen and
  • Zhi-Gang Xu

Beilstein J. Org. Chem. 2020, 16, 663–669, doi:10.3762/bjoc.16.63

Graphical Abstract
  • overnight (Scheme 1). The reaction provided the crude Ugi adduct 5a after the removal of methanol under reduced pressure. The crude residue was then exposed to a series of different cyclization reaction conditions. First, based on the previous works on the Dieckmann cyclization reaction [40][41], we
  •  1, entries 9–12. DMF was superior to other solvents with the highest yield. Then the microwave irradiation temperature was varied: at 80 °C for 10 min, a large fraction of the Ugi adduct 5a was still present in the product mixture (LC–MS determination); at 120 °C, the desired compound 7a was
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Published 09 Apr 2020

Copper-catalyzed enantioselective conjugate reduction of α,β-unsaturated esters with chiral phenol–carbene ligands

  • Shohei Mimura,
  • Sho Mizushima,
  • Yohei Shimizu and
  • Masaya Sawamura

Beilstein J. Org. Chem. 2020, 16, 537–543, doi:10.3762/bjoc.16.50

Graphical Abstract
  • protons of the acidic imidazolium C–H and phenol O–H groups of the L4·HBF4 adduct in the presence of CuCl to generate a phenoxy copper(I) species A. As a result, all LiOt-Bu (20 mol %) is consumed in this step. Thus, the system is neutral. Transmetalation between A and (EtO)2MeSiH produces the copper
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Published 31 Mar 2020
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