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Search for "heterocycle" in Full Text gives 338 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Exploring the scope of DBU-promoted amidations of 7-methoxycarbonylpterin

  • Anna R. Bockman and
  • Jeffrey M. Pruet

Beilstein J. Org. Chem. 2020, 16, 509–514, doi:10.3762/bjoc.16.46

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  • Anna R. Bockman Jeffrey M. Pruet Department of Chemistry, Valparaiso University, 1710 Chapel Dr, Valparaiso, IN 46383, USA 10.3762/bjoc.16.46 Abstract The synthetic utility of pterins is often hampered by the notorious insolubility of this heterocycle, slowing the development of medicinally
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Published 26 Mar 2020

KOt-Bu-promoted selective ring-opening N-alkylation of 2-oxazolines to access 2-aminoethyl acetates and N-substituted thiazolidinones

  • Qiao Lin,
  • Shiling Zhang and
  • Bin Li

Beilstein J. Org. Chem. 2020, 16, 492–501, doi:10.3762/bjoc.16.44

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  • proceeded well with heterocycle-containing chlorides such as 2-chloro-5-(chloromethyl)thiophene (4e), leading to 2-aminoethyl acetate product 3k in 66% yield which has potential as bifunctional monomer for polymerization. Furthermore, oxazole derivative 2,4,4-trimethyl-4,5-dihydrooxazole (2b) was also
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Published 25 Mar 2020

Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

  • Mingbing Zhong,
  • Xavier Pannecoucke,
  • Philippe Jubault and
  • Thomas Poisson

Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42

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  • large panel of carbazoles. The selectivity of the reaction using an unsymmetrical triarylamine depended on the electronic density of the aromatic ring, furnishing, in some cases constitutional isomers. Importantly, in the case of heteroaryl-substituted triarylamines, the heterocycle was incorporated in
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Published 23 Mar 2020

Architecture and synthesis of P,N-heterocyclic phosphine ligands

  • Wisdom A. Munzeiwa,
  • Bernard Omondi and
  • Vincent O. Nyamori

Beilstein J. Org. Chem. 2020, 16, 362–383, doi:10.3762/bjoc.16.35

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  • basicity in one ligand. The body discusses the synthetic protocols which focus on P–C, P–N-bond formation, substrate and nucleophile types and different N-heterocycle construction strategies. Selected references are given in relation to the applications of the ligands. Keywords: ligand synthesis; P,N
  • dibromomethane [2]. Substrate postfunctionalization and heterocycle construction Some heterocyclic precursors can be readily obtained via accessible synthetic protocols. The nitrogen-containing compounds can be constructed and grafted on the phosphine precursor. Some available phosphines and organic precursors
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Published 12 Mar 2020

Copper-promoted/copper-catalyzed trifluoromethylselenolation reactions

  • Clément Ghiazza and
  • Anis Tlili

Beilstein J. Org. Chem. 2020, 16, 305–316, doi:10.3762/bjoc.16.30

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  • heterocycle. This intermediate was then trifluoromethylselenylated by [(bpy)CuSeCF3]2. While benzofurans and benzothiophenes were prepared in moderate to good yields, only marginal yields were obtained with indole derivatives (up to 25%). Finally, the reactions could easily be scaled up to a gram scale. The
  • copper catalysis (Scheme 15, conditions I) [39]. Mechanistically, the authors proposed the formation of a silver(I)–SeCF3 adduct, followed by a transmetallation step, yielding the active CuSeCF3 species. Good to very good yields were obtained on a broad scope, including amide-, ester-, and heterocycle
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Published 03 Mar 2020

Ultrasonic-assisted unusual four-component synthesis of 7-azolylamino-4,5,6,7-tetrahydroazolo[1,5-a]pyrimidines

  • Yana I. Sakhno,
  • Maryna V. Murlykina,
  • Oleksandr I. Zbruyev,
  • Anton V. Kozyryev,
  • Svetlana V. Shishkina,
  • Dmytro Sysoiev,
  • Vladimir I. Musatov,
  • Sergey M. Desenko and
  • Valentyn A. Chebanov

Beilstein J. Org. Chem. 2020, 16, 281–289, doi:10.3762/bjoc.16.27

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  • 7-azolylaminotetrahydroazolo[1,5-a]pyrimidines. Keywords: 5-amino-1H-pyrazole-4-carbonitrile; 3-amino-1,2,4-triazole; 7-azolylaminotetrahydroazolo[1,5-a]pyrimidines; heterocycle; multicomponent reaction; ultrasonication; Introduction Tetrahydropyrimidines are heterocycles of high pharmacological
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Published 27 Feb 2020

Combination of multicomponent KA2 and Pauson–Khand reactions: short synthesis of spirocyclic pyrrolocyclopentenones

  • Riccardo Innocenti,
  • Elena Lenci,
  • Gloria Menchi and
  • Andrea Trabocchi

Beilstein J. Org. Chem. 2020, 16, 200–211, doi:10.3762/bjoc.16.23

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  • cyclopentenone ring [37], as this heterocycle is a powerful synthon for the synthesis of a variety of bioactive target molecules, due to the broad diversity of chemical modifications available for the enone structural motif [38]. The most common approach to access such chemotype is the Pauson–Khand (PK) reaction
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Published 12 Feb 2020

The use of isoxazoline and isoxazole scaffolding in the design of novel thiourea and amide liquid-crystalline compounds

  • Itamar L. Gonçalves,
  • Rafaela R. da Rosa,
  • Vera L. Eifler-Lima and
  • Aloir A. Merlo

Beilstein J. Org. Chem. 2020, 16, 175–184, doi:10.3762/bjoc.16.20

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  • heterocycle. Keywords: amides; isoxazole; isoxazoline; liquid crystal; thiourea; Introduction Thioureas are a structurally diversified group of organic compounds, with technological applications in different areas. The structural diversity of the thiourea moiety is linked to possibly one or both nitrogen
  • components, which may be substituted symmetrically or unsymmetrically [1]. Applications of this scaffold include complexing agents in anion sensors [2] organocatalysts [3], intermediates in heterocycle synthesis [1] and development of compounds with pharmacological effects [4]. Considering the importance of
  • mesophase. A monotropic smectic C mesophase (SmC) at 198 °C was observed for amide 19. Perfluorinated thioureas 17b and 18b presented an SmA mesophase, independent of the nature of the 5-membered heterocycle. The perfluorinated alkyl chain in both compounds is the reason of preference for a lamellar SmA
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Published 06 Feb 2020

Microwave-assisted synthesis of 2-substituted 4,5,6,7-tetrahydro-1,3-thiazepines from 4-aminobutanol

  • María C. Mollo,
  • Natalia B. Kilimciler,
  • Juan A. Bisceglia and
  • Liliana R. Orelli

Beilstein J. Org. Chem. 2020, 16, 32–38, doi:10.3762/bjoc.16.5

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  • energy associated to the formation of a seven-membered heterocycle would favour the competitive ring closure leading to the five-membered ring (Scheme 2, reaction a), which would involve attack of the carboxamide nitrogen to the ω-carbon. On the other hand, the higher nucleophilicity of the sulfur in the
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Published 06 Jan 2020

Emission solvatochromic, solid-state and aggregation-induced emissive α-pyrones and emission-tuneable 1H-pyridines by Michael addition–cyclocondensation sequences

  • Natascha Breuer,
  • Irina Gruber,
  • Christoph Janiak and
  • Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 2684–2703, doi:10.3762/bjoc.15.262

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  • well as on the electronic substitution pattern of the alkynone. While electron-donating groups furnish α-pyrones as main products, electron-withdrawing groups predominantly give the corresponding 1H-pyridines. Both heterocycle classes fluoresce in solution and in the solid state. In particular
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Published 12 Nov 2019

Unexpected one-pot formation of the 1H-6a,8a-epiminotricyclopenta[a,c,e][8]annulene system from cyclopentanone, ammonia and dimethyl fumarate. Synthesis of highly strained polycyclic nitroxide and EPR study

  • Sergey A. Dobrynin,
  • Igor A. Kirilyuk,
  • Yuri V. Gatilov,
  • Andrey A. Kuzhelev,
  • Olesya A. Krumkacheva,
  • Matvey V. Fedin,
  • Michael K. Bowman and
  • Elena G. Bagryanskaya

Beilstein J. Org. Chem. 2019, 15, 2664–2670, doi:10.3762/bjoc.15.259

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  • heterocycle formation [11]. Presumably, a prototropic shift in the enamine-imine intermediate 4 is followed by electrocyclization to the cyclic azomethine ylide, which then reacts with dimethyl fumarate in a 1,3-dipolar cycloaddition. The suggested mechanism accounts for the trans-position of the methyne
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Published 07 Nov 2019

Plasma membrane imaging with a fluorescent benzothiadiazole derivative

  • Pedro H. P. R. Carvalho,
  • Jose R. Correa,
  • Karen L. R. Paiva,
  • Daniel F. S. Machado,
  • Jackson D. Scholten and
  • Brenno A. D. Neto

Beilstein J. Org. Chem. 2019, 15, 2644–2654, doi:10.3762/bjoc.15.257

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  • and first excited state S1 (∆ρ = ρS1 − ρS0), as shown in Figure 4D, highlights the directionality of the electron density transfer with a great deal of ICT between the cationic heterocycle and the BTD core, which stabilizes the excited state of the synthesized chromophore. These theoretical results
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Published 06 Nov 2019

Combining the Ugi-azide multicomponent reaction and rhodium(III)-catalyzed annulation for the synthesis of tetrazole-isoquinolone/pyridone hybrids

  • Gerardo M. Ojeda,
  • Prabhat Ranjan,
  • Pavel Fedoseev,
  • Lisandra Amable,
  • Upendra K. Sharma,
  • Daniel G. Rivera and
  • Erik V. Van der Eycken

Beilstein J. Org. Chem. 2019, 15, 2447–2457, doi:10.3762/bjoc.15.237

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  • processes has remained underexploited [27]. Thus, we envisioned that the combination of an Ugi-azide-4CR with modern metal-catalyzed C–C bond-forming methods would enable access to structurally novel compounds featuring hybrid heterocycle platforms. We focused on metal-catalyzed annulation approaches that
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Published 16 Oct 2019

Thermal stability of N-heterocycle-stabilized iodanes – a systematic investigation

  • Andreas Boelke,
  • Yulia A. Vlasenko,
  • Mekhman S. Yusubov,
  • Boris J. Nachtsheim and
  • Pavel S. Postnikov

Beilstein J. Org. Chem. 2019, 15, 2311–2318, doi:10.3762/bjoc.15.223

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  • Federation Department of Solid State Engineering, University of Chemistry and Technology, 16628 Prague, Czech Republic 10.3762/bjoc.15.223 Abstract The thermal stability of pseudocyclic and cyclic N-heterocycle-stabilized (hydroxy)aryl- and mesityl(aryl)-λ3-iodanes (NHIs) through thermogravimetric analysis
  • stability with reactivity in a model oxygenation. Keywords: differential scanning calorimetry; hypervalent iodine; N-heterocycle; stability; thermogravimetry; Introduction Hypervalent iodine compounds, in particular aryl-λ3-iodanes, have found wide spread applications as oxidants and electrophilic group
  • promising properties in terms of reactivity and stability. However, iodanes stabilized by nitrogen-based ligands, in particular N-heterocycles are still underexplored [22][23][24][25][26][27][28]. Recently, our groups investigated systematically cyclic and pseudocyclic N-heterocycle-stabilized iodanes (NHIs
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Published 27 Sep 2019

1,2,3-Triazolium macrocycles in supramolecular chemistry

  • Mastaneh Safarnejad Shad,
  • Pulikkal Veettil Santhini and
  • Wim Dehaen

Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211

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  • polymers etc. [14][15]. Noncovalent interactions play a dynamic role in the binding mechanism of triazoles as macrocyclic receptors. It has been reported that the combined effects of both an electron lone pair on the nitrogen of the heterocycle and the acidic C5–H proton make 1,2,3-triazoles interesting
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Published 12 Sep 2019

1,2,3,4-Tetrahydro-1,4,5,8-tetraazaanthracene revisited: properties and structural evidence of aromaticity loss

  • Arnault Heynderickx,
  • Sébastien Nénon,
  • Olivier Siri,
  • Vladimir Lokshin and
  • Vladimir Khodorkovsky

Beilstein J. Org. Chem. 2019, 15, 2059–2068, doi:10.3762/bjoc.15.203

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  • (THTAA) – a heterocycle involving both >N–H donating and =N– accepting moieties – have been reinvestigated. Unlike previously reported, THTAA is a thermally stable compound that can be re-sublimed at 300–310 °C without decomposition. Controlled introduction of substituents at the nitrogen atoms of THTAA
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Published 28 Aug 2019

Reactions of 2-carbonyl- and 2-hydroxy(or methoxy)alkyl-substituted benzimidazoles with arenes in the superacid CF3SO3H. NMR and DFT studies of dicationic electrophilic species

  • Dmitry S. Ryabukhin,
  • Alexey N. Turdakov,
  • Natalia S. Soldatova,
  • Mikhail O. Kompanets,
  • Alexander Yu. Ivanov,
  • Irina A. Boyarskaya and
  • Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2019, 15, 1962–1973, doi:10.3762/bjoc.15.191

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  • reaction [14]. Recently, several hydroxyalkylation reactions followed by alkylation of arenes have been reported involving heterocycle-based superelectrophiles: pyridines, thiazoles, quinolines, isoquinolines, pyrazines, pyrazoles, imidazole and furans, bearing a formyl (carbonyl) group [15][16][17][18][19
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Published 19 Aug 2019

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

  • Gagandeep Kour Reen,
  • Ashok Kumar and
  • Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

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  • that the presence of copper salt is mandatory for the formation of the fused heterocycle as its absence resulted in the formation of the enaminone only. The imines 118, generated in situ via the loss of nitrogen from azide derivatives, were found to be reactive towards 1,3-dipoles 117 to form diverse
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Published 19 Jul 2019

Synthesis of ([1,2,4]triazolo[4,3-a]pyridin-3-ylmethyl)phosphonates and their benzo derivatives via 5-exo-dig cyclization

  • Aleksandr S. Krylov,
  • Artem A. Petrosian,
  • Julia L. Piterskaya,
  • Nataly I. Svintsitskaya and
  • Albina V. Dogadina

Beilstein J. Org. Chem. 2019, 15, 1563–1568, doi:10.3762/bjoc.15.159

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  • , hypervalent iodine reagents, etc. The synthetic methods towards diverse [1,2,4]triazolo[3,4-a]pyridines have been reviewed in detail [12][13]. It should be noted that the use of acetylene species to create this heterocycle (including triazole ring) is presented only by few examples. There has been reported
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Published 12 Jul 2019

Superelectrophilic carbocations: preparation and reactions of a substrate with six ionizable groups

  • Sean H. Kennedy,
  • Makafui Gasonoo and
  • Douglas A. Klumpp

Beilstein J. Org. Chem. 2019, 15, 1515–1520, doi:10.3762/bjoc.15.153

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  • proposed involving tetra-, penta-, or hexacationic species. Keywords: cation; Friedel–Crafts; heterocycle; superacid; superelectrophile; Introduction During the 1970s and 80s, Olah and co-workers described the novel chemistry of highly-charged organic cationic species. This work lead to the concept of
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Published 09 Jul 2019

Synthesis of pyrrolo[1,2-a]quinolines by formal 1,3-dipolar cycloaddition reactions of quinolinium salts

  • Anthony Choi,
  • Rebecca M. Morley and
  • Iain Coldham

Beilstein J. Org. Chem. 2019, 15, 1480–1484, doi:10.3762/bjoc.15.149

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  • could be converted to other derivatives by Suzuki–Miyaura coupling, reduction or oxidation reactions. Keywords: azomethine ylide; cycloaddition; heterocycle; pyrrolidine; stereoselective; Introduction Cycloaddition reactions of azomethine ylides are an important class of pericyclic reactions that give
  • ylide, or by condensation of a primary amine with an aldehyde to give an imine followed by prototropy or deprotonation to give N-metalated azomethine ylides (see, for example, [5][6][7][8][9][10][11][12][13][14][15][16][17][18]). An alternative method is to prepare a salt of a heterocycle, typically by
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Published 03 Jul 2019

Steroid diversification by multicomponent reactions

  • Leslie Reguera,
  • Cecilia I. Attorresi,
  • Javier A. Ramírez and
  • Daniel G. Rivera

Beilstein J. Org. Chem. 2019, 15, 1236–1256, doi:10.3762/bjoc.15.121

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  • displaying biological activities such as antimicrobial, antiviral and anti-inflammatory, among others. Scheme 3 exemplifies the reaction of cholestan-6-one 7 with 2-aminopyridine and phenyl isocyanide to afford the heterocycle–steroid hybrid 8 in good yield and diastereoselectivity, whereas different
  • Passerini and Ugi reactions. 3 Synthesis of steroid-fused heterocycles The modification of the steroidal nucleus by attaching a heterocycle to this hydrophobic scaffold has been traditionally used as an effective way to modulate the biological activity of these biomolecules. In this regard, pentacyclic
  • steroids. To our knowledge, there are no reports of fused heterocyclic or carbocyclic rings on the ring C of the steroid. In this section, we discuss different reports on the synthesis of steroid-fused heterocycle using MCRs. Wang et al. [39] developed a synthetic route based on the Biginelli reaction for
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Published 06 Jun 2019

Precious metal-free molecular machines for solar thermal energy storage

  • Meglena I. Kandinska,
  • Snejana M. Kitova,
  • Vladimira S. Videva,
  • Stanimir S. Stoyanov,
  • Stanislava B. Yordanova,
  • Stanislav B. Baluschev,
  • Silvia E. Angelova and
  • Aleksey A. Vasilev

Beilstein J. Org. Chem. 2019, 15, 1096–1106, doi:10.3762/bjoc.15.106

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  • aggregated much faster than its methyl-substituted analogue 4b. From another hand the substituent in the 5-position of the benzothiazole heterocycle sterically hinders the rotation of the alkylsulfo-anchoring group and thus plays the role of a controller with regard to its direction towards the crown ether
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Published 14 May 2019

Multicomponent reactions (MCRs): a useful access to the synthesis of benzo-fused γ-lactams

  • Edorta Martínez de Marigorta,
  • Jesús M. de Los Santos,
  • Ana M. Ochoa de Retana,
  • Javier Vicario and
  • Francisco Palacios

Beilstein J. Org. Chem. 2019, 15, 1065–1085, doi:10.3762/bjoc.15.104

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  • -oxindoles; Introduction Pyrrolidin-2-ones (I, Figure 1) are heterocycles that contain a γ-lactam ring that can be found in many biologically active compounds with natural or synthetic origin [1]. When an aryl group is fused to the 3- and 4-positions of the five-membered heterocycle, isoindolinones (II
  • heterocycle containing five- and six-membered fused N-heterocyclic rings (Scheme 16), including the γ-lactam unit. The first synthesis of this class of compounds was reported by Pal et al. [96] with the aid of montmorillonite K10 as a recyclable catalyst in ethanol. With these environmentally friendly
  • prepared in moderate to good yields. A wide scope of aryldiazonium reagents 68 bearing electron-donating and electron-withdrawing groups worked well in the reaction, but when a pyridyl heterocycle was employed, the reaction failed. On the acrylamide side, activating and deactivating groups worked similarly
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Published 08 May 2019

Synthesis of (macro)heterocycles by consecutive/repetitive isocyanide-based multicomponent reactions

  • Angélica de Fátima S. Barreto and
  • Carlos Kleber Z. Andrade

Beilstein J. Org. Chem. 2019, 15, 906–930, doi:10.3762/bjoc.15.88

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  • involving a tandem combination of Groebke–Blackburn–Bienaymé and Ugi reaction for the synthesis of a complex heterocycle [26]. 5CR involving a tandem combination of Groebke–Blackburn–Bienaymé and Passerini reaction for the synthesis of a complex heterocycle [26]. Synthesis of tubugis via three consecutive
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Published 15 Apr 2019
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