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Search for "cyclizations" in Full Text gives 199 result(s) in Beilstein Journal of Organic Chemistry.

Recent synthesis of thietanes

  • Jiaxi Xu

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

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  • + 2] cycloadditions, ring expansions and contractions, nucleophilic cyclizations, and some miscellaneous methods. The recently developed methods provide some new strategies for the efficient preparation of thietanes and their derivatives. This review focuses on the synthetic methods to construct
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Published 22 Jun 2020

[3 + 2] Cycloaddition with photogenerated azomethine ylides in β-cyclodextrin

  • Margareta Sohora,
  • Leo Mandić and
  • Nikola Basarić

Beilstein J. Org. Chem. 2020, 16, 1296–1304, doi:10.3762/bjoc.16.110

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  • the macrocyclic host affected the stereochemistry of the reaction. Moreover, we studied photodecarboxylation reactions initiated by the phthalimide chromophore [17][18][19] and applied them in cyclizations with memory of chirality [20] and diastereoselective peptide cyclizations [21
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Published 12 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
  • reactions of oxime radicals. These reactions are classified into cyclizations involving C–H bond cleavage and cyclizations involving a double C=C bond cleavage. Keywords: iminoxyl radicals; isoxazolines; oxidative cyclization; oxime radicals; oximes; Introduction Free radicals in which an unpaired
  • under the action of photocatalysts [109][110], cyclization of nitroso intermediate [111], etc. [112][113]. At least some of these reactions do not involve oxime radicals as intermediates. It should be noted that free-radical cyclizations mediated by iminoxyl radicals frequently afford products that are
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Published 05 Jun 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
  • metathesis (RCM) [67][68]. Starting from 3-cyanocyclohex-2-enone, the authors obtained a versatile intermediate able to provide the appropriate dienyne precursors (A–C, Scheme 4) by multicomponent Grignard addition-alkylations. Through divergent cyclizations involving a chemoselective enyne metathesis
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Published 16 Apr 2020

Understanding the role of active site residues in CotB2 catalysis using a cluster model

  • Keren Raz,
  • Ronja Driller,
  • Thomas Brück,
  • Bernhard Loll and
  • Dan T. Major

Beilstein J. Org. Chem. 2020, 16, 50–59, doi:10.3762/bjoc.16.7

Graphical Abstract
  • electrophilic cyclizations to generate intermediate A. Intermediate A undergoes a 1,5-hydride shift, forming intermediate B. A subsequent cyclization forms intermediate C. Intermediate C generates intermediate E via one of two possible pathways: either a direct 1,3-hydride shift or an indirect pathway involving
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Published 08 Jan 2020

Bacterial terpene biosynthesis: challenges and opportunities for pathway engineering

  • Eric J. N. Helfrich,
  • Geng-Min Lin,
  • Christopher A. Voigt and
  • Jon Clardy

Beilstein J. Org. Chem. 2019, 15, 2889–2906, doi:10.3762/bjoc.15.283

Graphical Abstract
  • a linear polyene with branching methyl groups that form the core hydrocarbon structure in a single enzyme-catalyzed step [9]. The enzyme, which is called terpene cyclase, holds the linear methyl-branched polyene in a defined conformation that initiates a series of carbocation-driven cyclizations and
  • oxidative [66] and reductive cyclizations [67] have been described. The reductive cyclization reaction is particularly noteworthy, as the reduction and cyclization step are catalyzed by two distinct enzymes [67]. These examples show that the classical division of terpene biosynthesis into a cyclization and
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Published 29 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

Graphical Abstract
  • could form isoquinolones and pyridones linked to a tetrazole ring, since such class of hybrid compounds is not described in the literature. Several protocols based on C–H activation or metal-catalyzed cyclizations are known to generate the isoquinolone and pyridone moieties and further assist their post
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Published 16 Oct 2019

Functionalization of 4-bromobenzo[c][2,7]naphthyridine via regioselective direct ring metalation. A novel approach to analogues of pyridoacridine alkaloids

  • Benedikt C. Melzer,
  • Alois Plodek and
  • Franz Bracher

Beilstein J. Org. Chem. 2019, 15, 2304–2310, doi:10.3762/bjoc.15.222

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  • -bromobenzo[c][2,7]naphthyridines 12a–d in hand we aimed at the synthesis of the respective pyrido[2,3,4-kl]acridines by intramolecular ring-closing steps. Similar C–C couplings were performed previously by application of palladium-catalysed cross-coupling reactions, photochemical cyclizations or even in
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Published 26 Sep 2019

Click chemistry towards thermally reversible photochromic 4,5-bisthiazolyl-1,2,3-triazoles

  • Chenxia Zhang,
  • Kaori Morinaka,
  • Mahmut Kose,
  • Takashi Ubukata and
  • Yasushi Yokoyama

Beilstein J. Org. Chem. 2019, 15, 2161–2169, doi:10.3762/bjoc.15.213

Graphical Abstract
  • could be considered reasonable that the reactions of the sterically more congested ethynes and benzyl azide gave triazoles with less chemical yields. Details of the synthesis are described in Supporting Information File 1. Photochromic reactions Photochemical cyclizations Triazoles were dissolved in
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Published 13 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

Graphical Abstract
  • highly functionalized 1,2,3-triazolium macrocycles under optimized reaction conditions, although cyclizations also have been carried out starting from triazolium building blocks (Figure 2). Using a small variation in the reaction protocols of the click reaction, iodine atoms can be introduced at the 5
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Published 12 Sep 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

Graphical Abstract
  • widely described in the literature encompassing a number of reactions like oxidative cyclizations [11], oxidative coupling reactions [12], Vilsmeier type cyclizations [13], intramolecular aminooxygenation/C–H amination reactions [14][15], Groebke–Blackburn–Bienayme (GBB) reactions [16][17][18] and many
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Published 19 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

Graphical Abstract
  • the 1,4-dihydropyridine scaffold. As depicted in Scheme 14, compound 46 was later subjected to a variety of post-MCR cyclizations, including the reaction with carboxylic acids to form the fused steroidal pyridopyrimidinones 47 and with carbon disulfide to form pyridopyrimidinedithione 48 in very good
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Published 06 Jun 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

Graphical Abstract
  • alkynylpalladium complex 25 in the proposed pathway. Other benzoic acid derivatives such as those bearing a formyl substituent at the ortho position also take part in several multicomponent cyclizations leading to isoindolinones. Thus, 2-formylbenzoate 29, primary amines 2 and terminal alkynes 18 react under
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Published 08 May 2019

Catalytic asymmetric oxo-Diels–Alder reactions with chiral atropisomeric biphenyl diols

  • Chi-Tung Yeung,
  • Wesley Ting Kwok Chan,
  • Wai-Sum Lo,
  • Ga-Lai Law and
  • Wing-Tak Wong

Beilstein J. Org. Chem. 2019, 15, 955–962, doi:10.3762/bjoc.15.92

Graphical Abstract
  • reactions. Oxo-Diels–Alder (oxo-DA) reactions between electron-poor aldehydes and electron-rich dienes such as Danishefsky’s dienes or Brassard’s dienes are efficient ways to construct oxygen-containing six-membered heterocycles via [4 + 2] cyclizations, and have been dominated by metal-based chiral Lewis
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Published 18 Apr 2019

A diastereoselective approach to axially chiral biaryls via electrochemically enabled cyclization cascade

  • Hong Yan,
  • Zhong-Yi Mao,
  • Zhong-Wei Hou,
  • Jinshuai Song and
  • Hai-Chao Xu

Beilstein J. Org. Chem. 2019, 15, 795–800, doi:10.3762/bjoc.15.76

Graphical Abstract
  • –Hammett scenario (Scheme 4) [42]. Specifically, the equilibrium of the conformations IV and IV′ is much faster than their respectively cyclizations to give V and V′. Since TS2 is relatively lower in energy than TS3, V is formed as the major product. Conclusion In summary, we have developed a
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Published 28 Mar 2019

The LANCA three-component reaction to highly substituted β-ketoenamides – versatile intermediates for the synthesis of functionalized pyridine, pyrimidine, oxazole and quinoxaline derivatives

  • Tilman Lechel,
  • Roopender Kumar,
  • Mrinal K. Bera,
  • Reinhold Zimmer and
  • Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2019, 15, 655–678, doi:10.3762/bjoc.15.61

Graphical Abstract
  • too bulky. In these cases, no sufficient concentrations of Z-EN or of L are formed and hence the 1,2-diketones DK are obtained as the products. It should also be mentioned that isolated 1,2-diketones DK do not undergo cyclizations to OX even after extended treatment with trifluoroacetic acid. As an
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Published 13 Mar 2019

Ruthenium-based olefin metathesis catalysts with monodentate unsymmetrical NHC ligands

  • Veronica Paradiso,
  • Chiara Costabile and
  • Fabia Grisi

Beilstein J. Org. Chem. 2018, 14, 3122–3149, doi:10.3762/bjoc.14.292

Graphical Abstract
  • noteworthy that complex 174 was found to be very competent also in cyclizations to form six and seven-membered ring olefins (175 and 177, Scheme 16), conversely to the other C1-symmetric systems previously reported. On the other hand, coherently with 164 and 172, the best results were achieved without the
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Published 28 Dec 2018

Synthesis of cis-hydrindan-2,4-diones bearing an all-carbon quaternary center by a Danheiser annulation

  • Gisela V. Saborit,
  • Carlos Cativiela,
  • Ana I. Jiménez,
  • Josep Bonjoch and
  • Ben Bradshaw

Beilstein J. Org. Chem. 2018, 14, 2597–2601, doi:10.3762/bjoc.14.237

Graphical Abstract
  • takes place from polyfunctionalized cyclohexanones or related compounds through a Michael reaction [7], successive inter- and intramolecular radical processes [8], intramolecular carbene addition/cyclization [9][10], aldol cyclizations either under Lewis acid catalysis [11] or from diazoketones in the
  • through ring-expanding cyclopentane annulations based on a Prins–pinacol rearrangement [17][18] and Au(I)-catalyzed pinacol-terminated 1,6-enyne cyclizations [19][20], the C3a–C7a bond formation occurring in the last step of both procedures. Finally, Snyder gained access to the type A hydrindane nucleus
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Published 09 Oct 2018

Gold-catalyzed post-Ugi alkyne hydroarylation for the synthesis of 2-quinolones

  • Xiaochen Du,
  • Jianjun Huang,
  • Anton A. Nechaev,
  • Ruwei Yao,
  • Jing Gong,
  • Erik V. Van der Eycken,
  • Olga P. Pereshivko and
  • Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2018, 14, 2572–2579, doi:10.3762/bjoc.14.234

Graphical Abstract
  • functionalization [25][26][27][28][29] of the 2-quinolone scaffold has become a budding research trend. In the last decade, a great number of efficient approaches has been developed utilizing transition metal-catalyzed [30][31][32], Lewis acid-mediated [33], and radical cyclizations [34] of various aniline
  • –Crafts-type cyclizations involving attack of electron-rich arenes on the triple bonds, leading to the formation of a great number of fused [50][51][52][53] and spirocyclic structures [54][55][56][57][58][59]. In addition, Ugi adducts have already been successfully utilized for the diversity-oriented
  • cyclizations of 7p–r required further optimization of the reaction conditions (Tables 2–4) and were complicated due the formation of regioisomeric products. After all, 2-quinolones 8p and 8q were isolated in good yields from gold-catalyzed reactions in hexafluoroisopropanol (HFIP), while 2-quinolone 8r was
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Published 04 Oct 2018

Synthesis of eunicellane-type bicycles embedding a 1,3-cyclohexadiene moiety

  • Alex Frichert,
  • Peter G. Jones and
  • Thomas Lindel

Beilstein J. Org. Chem. 2018, 14, 2461–2467, doi:10.3762/bjoc.14.222

Graphical Abstract
  • coupling to 16 and deprotection to 17 worked satisfyingly. As in the case of a benzene partial structure (8), it was a diol that was formed from 17 under McMurry conditions (20 equiv TiCl4, 40 equiv Zn, THF, rt). No alkene was detected. McMurry-type pinacol cyclizations have shown varying degrees of
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Published 20 Sep 2018

One hundred years of benzotropone chemistry

  • Arif Dastan,
  • Haydar Kilic and
  • Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

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Published 23 May 2018

Photocatalytic formation of carbon–sulfur bonds

  • Alexander Wimmer and
  • Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

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  • the alkene moiety of the 1,7-enyne, two consecutive cyclizations lead to the final sulfonylated benzo[α]fluoren-5-one. Electron and proton transfer and subsequent formation of dihydrogen close the catalytic cycle and regenerate the photocatalyst. Sulfinamides Formation of sulfoxides A new method for
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Published 05 Jan 2018

From dipivaloylketene to tetraoxaadamantanes

  • Gert Kollenz and
  • Curt Wentrup

Beilstein J. Org. Chem. 2018, 14, 1–10, doi:10.3762/bjoc.14.1

Graphical Abstract
  • can undergo transannular cyclizations to yield initial intermediates 15 and 17. However, the latter compounds rearrange, whereby an O–C=O moiety in the 1,3-dioxinone becomes a carboxylic acid function in the resulting, axially chiral 2,6,9-trioxabicyclo[3.3.1]nonadienes (bisdioxines) 8, 10, and 11
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Published 02 Jan 2018

Reagent-controlled regiodivergent intermolecular cyclization of 2-aminobenzothiazoles with β-ketoesters and β-ketoamides

  • Irwan Iskandar Roslan,
  • Kian-Hong Ng,
  • Gaik-Khuan Chuah and
  • Stephan Jaenicke

Beilstein J. Org. Chem. 2017, 13, 2739–2750, doi:10.3762/bjoc.13.270

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  • traditional Pd-catalyzed aryl–heteroaryl coupling to biaryls [57]. Since then, KOt-Bu has been used as a mediator for various reactions including aryl–aryl coupling [58][59][60][61][62][63], inter- and intramolecular cyclizations [64][65][66][67][68], amidation [69], alkenylation [70], oxidation [71] and
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Published 18 Dec 2017

Synthesis of benzannelated sultams by intramolecular Pd-catalyzed arylation of tertiary sulfonamides

  • Valentin A. Rassadin,
  • Mirko Scholz,
  • Anastasiia A. Klochkova,
  • Armin de Meijere and
  • Victor V. Sokolov

Beilstein J. Org. Chem. 2017, 13, 1932–1939, doi:10.3762/bjoc.13.187

Graphical Abstract
  • , sultams have been prepared employing Diels–Alder reactions, radical cyclizations, reductions of sulfonylimines, ring-closing metatheses, nucleophilic aromatic substitutions and Heck cyclizations [14][15][16]. Earlier on, our group has developed versatile syntheses of sultams based on the transformation of
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Published 12 Sep 2017
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