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Search for "cyclization reaction" in Full Text gives 207 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Nucleophilic and electrophilic cyclization of N-alkyne-substituted pyrrole derivatives: Synthesis of pyrrolopyrazinone, pyrrolotriazinone, and pyrrolooxazinone moieties

  • Işıl Yenice,
  • Sinan Basceken and
  • Metin Balci

Beilstein J. Org. Chem. 2017, 13, 825–834, doi:10.3762/bjoc.13.83

Graphical Abstract
  • pyrrole ring and the imine double bond. With these encouraging results in hand, we embarked on the evaluation of the substrate scope for this useful transformation. The compounds 7a, 7b, and 7d were submitted to a cyclization reaction under the same reaction conditions applied to compound 7c. As shown in
  • Scheme 2, compounds 7a and 7d formed 2-aminopyrrolopyrazinone derivatives 12a and 12d, whereas 7b furnished pyrrolotriazinone derivative 13b. The electronic nature of the substituents attached to the alkyne determines the mode of the cyclization reaction. Since the electron-donating methoxy group
  • to afford pyrrolotriazinone moiety 13. After completion of the nucleophilic cyclization reactions, we desired to activate the triple bond with iodine to synthesize pyrrolooxazinone derivatives via an electrophilic intramolecular cyclization reaction. For this purpose, N-alkyne-substituted methyl 1H
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Published 04 May 2017

A practical and efficient approach to imidazo[1,2-a]pyridine-fused isoquinolines through the post-GBB transformation strategy

  • Taofeng Shao,
  • Zhiming Gong,
  • Tianyi Su,
  • Wei Hao and
  • Chao Che

Beilstein J. Org. Chem. 2017, 13, 817–824, doi:10.3762/bjoc.13.82

Graphical Abstract
  • acetylene unit may then undergo a sequential 6-exo-dig cyclization/retro-ene reaction to form the desired imidazo[1,2-a]pyridine-fused isoquinoline 6a. The cyclization reaction could be realized with the aid of silver or gold catalysts [51][52]. With this idea in mind, we commenced our studies by
  • detected under these mild conditions. Subsequent heating of 4a in refluxing 1,4-dioxane or toluene failed to deliver the expected product 6a, even under acidic or basic conditions. Then, we turned to Ag and Au catalysts and investigated the metal-catalyzed intramolecular cyclization reaction of 4a and the
  • product was obtained in refluxing CH3CN or 1,4-dioxane (Table 1, entries 1–4). It revealed that the solvent plays a key role in this cyclization reaction. For comparison, we tested also AgSbF6 as the catalyst and it was found to be less effective than AgOTf (Table 1, entry 5). To improve the reaction
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Published 04 May 2017

N-Propargylamines: versatile building blocks in the construction of thiazole cores

  • S. Arshadi,
  • E. Vessally,
  • L. Edjlali,
  • R. Hosseinzadeh-Khanmiri and
  • E. Ghorbani-Kalhor

Beilstein J. Org. Chem. 2017, 13, 625–638, doi:10.3762/bjoc.13.61

Graphical Abstract
  • syntheses of a series of multiply substituted thiazolidines 33 via the cyclization reaction of secondary N-propargylamines 32 with blocked N-isothiocyanate precursors 31. The desired N-isocyanates A are produced in situ upon heating or treatment with a base, in acetonitrile under microwave irradiation
  • converted to the corresponding vinylthiazolines 38 through the treatment with dithioic acids 37 in the presence of EDCI in dichloromethane. This transformation is believed to occur through a tandem coupling–cyclization reaction. The authors showed that the treatment of 38 with DBU at 0 °C provided thiazoles
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Published 30 Mar 2017

Synthesis of 1-indanones with a broad range of biological activity

  • Marika Turek,
  • Dorota Szczęsna,
  • Marek Koprowski and
  • Piotr Bałczewski

Beilstein J. Org. Chem. 2017, 13, 451–494, doi:10.3762/bjoc.13.48

Graphical Abstract
  • the carbonylative cyclization reaction of carboxylic acid methyl and ethyl esters 42 which led to the formation of 1-indanones 43 [33]. This reaction was carried out in acetonitrile, in the presence of triethylamine, under carbon monoxide atmosphere, achieving efficiency in the range of 88–92%, when
  • 83. The latter underwent a Michael cyclization reaction to afford 84. Finally, dehydratation of 84 gave the spiro bis-indane product 85 (Scheme 27). A new method to synthesize 2-benzylidene-1-indanone derivatives 88a–d has been proposed in 2014 by Álvarez-Toledano et al. [52]. These derivatives were
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Published 09 Mar 2017

Brønsted acid-mediated cyclization–dehydrosulfonylation/reduction sequences: An easy access to pyrazinoisoquinolines and pyridopyrazines

  • Ramana Sreenivasa Rao and
  • Chinnasamy Ramaraj Ramanathan

Beilstein J. Org. Chem. 2017, 13, 428–440, doi:10.3762/bjoc.13.46

Graphical Abstract
  • the cyclization reaction in the presence of TfOH at room temperature to generate a potential precursor for the synthesis of praziquantel. To realize the cyclization, the imide 7h was treated with TfOH under neat conditions at 70 °C, quite unfortunately to witness the decomposition of imide 7h. This
  • the potassium salt of N-benzyliminodiacetic acid in THF at reflux to furnish the expected imides 8a–c, 8h, and 8i in good yields (Scheme 6). The imide 8h was subjected to the cyclization reaction conditions using 6 equivalents of TfOH under neat conditions at 70 °C followed by reduction using NaBH4
  • pyrazinoisoquinolines, 2-oxopiperazines and aldose reductase inhibitors (ALR2). HRMS spectra of aliquot generated from cyclization reaction of 7c. ORTEP diagrams of compound 9b and 10a. Comparison of previous reports with present work for piperazine-2,6-dione synthesis. Coupling of N-benzenesulfonyliminodiacetic acid
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Published 07 Mar 2017

The reductive decyanation reaction: an overview and recent developments

  • Jean-Marc R. Mattalia

Beilstein J. Org. Chem. 2017, 13, 267–284, doi:10.3762/bjoc.13.30

Graphical Abstract
  • decyanation in metal dissolving conditions coupled with deprotection [30]. TBDMS = tert-butyldimethylsilyl. Preparation of α,ω-dienes [18][33]. Cyclization reaction using a radical probe [18]. Synthesis of (±)-xanthorrhizol (8) [39]. Mechanism for the reduction of α-aminonitriles by hydride donors. Synthesis
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Published 13 Feb 2017

Regiochemistry of cyclocondensation reactions in the synthesis of polyazaheterocycles

  • Patrick T. Campos,
  • Leticia V. Rodrigues,
  • Andrei L. Belladona,
  • Caroline R. Bender,
  • Juliana S. Bitencurt,
  • Fernanda A. Rosa,
  • Davi F. Back,
  • Helio G. Bonacorso,
  • Nilo Zanatta,
  • Clarissa P. Frizzo and
  • Marcos A. P. Martins

Beilstein J. Org. Chem. 2017, 13, 257–266, doi:10.3762/bjoc.13.29

Graphical Abstract
  • , thiophene-2-glyoxylic acid, and N-(2-amino-4-nitrophenyl)acetamide, in accordance with the mechanism proposed in this work. To rationalize why the cyclization reaction between the amidines 8g,h and the α-ketoester did not occur, the HOMO coefficient and charge densities for the nitrogens of the amidine were
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Published 10 Feb 2017

Poly(ethylene glycol)s as grinding additives in the mechanochemical preparation of highly functionalized 3,5-disubstituted hydantoins

  • Andrea Mascitti,
  • Massimiliano Lupacchini,
  • Ruben Guerra,
  • Ilya Taydakov,
  • Lucia Tonucci,
  • Nicola d’Alessandro,
  • Frederic Lamaty,
  • Jean Martinez and
  • Evelina Colacino

Beilstein J. Org. Chem. 2017, 13, 19–25, doi:10.3762/bjoc.13.3

Graphical Abstract
  • investigated in the presence of various poly(ethylene) glycols (PEGs), as safe grinding assisting agents (liquid-assisted grinding, LAG). A comparative study under dry-grinding conditions was also performed. The results showed that the cyclization reaction was influenced by the amount of the PEG grinding
  • from α-amino methyl esters 1, via an in situ intramolecular cyclization reaction of the ureido derivative B, which was obtained from N-carbamoylimidazole activated amino ester derivative A by reaction with various amines [9][10][11] (Scheme 1). Hanusa’s formalism was used to represent the reaction
  • its enantiomer (Table 2, entry 3). Therefore, the one-pot two-steps cyclization reaction was investigated with different amino ester/amine combinations (H-AA-OMe/R2-NH2) and comparative experiments using dry- or wet-grinding with PEGs (Mw = 2000 and 3400, 450 mg mmol−1) were also performed (Table 3
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Published 04 Jan 2017

The direct oxidative diene cyclization and related reactions in natural product synthesis

  • Juliane Adrian,
  • Leona J. Gross and
  • Christian B. W. Stark

Beilstein J. Org. Chem. 2016, 12, 2104–2123, doi:10.3762/bjoc.12.200

Graphical Abstract
  • ][68]. In 2013, the Fürstner group published a successful approach to amphidinolide F (24) applying an oxidative type C Mukaiyama cyclization reaction for the THF segment 22 (Scheme 7) [69][70]. Therefore, enantiomerically pure epoxide 20 was converted to 5-hydroxyalkene 21, the oxidative cyclization
  • precursor in this total synthesis. The subsequent cobalt-catalyzed cyclization reaction proceeded chemoselectively in the presence of the alkyne moiety and provided the trans-disubstituted THF 22 in high yield [69][70][71]. Finally, building block 23, one important fragment in the total synthesis of
  • , it has to be noted that the trans-THF was not directly formed in an oxidative cyclization reaction but rather through a subsequent sequential solvolysis/hydride shift/intramolecular reduction cascade. Another total synthesis of cis-sylvaticin (40) has been published by Brown and co-workers in 2008
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Published 30 Sep 2016

Microwave-assisted cyclizations promoted by polyphosphoric acid esters: a general method for 1-aryl-2-iminoazacycloalkanes

  • Jimena E. Díaz,
  • María C. Mollo and
  • Liliana R. Orelli

Beilstein J. Org. Chem. 2016, 12, 2026–2031, doi:10.3762/bjoc.12.190

Graphical Abstract
  • trimethylsilyl polyphosphate (PPSE) in solvent-free conditions allowed for the synthesis of 1-aryl-2-iminopiperidines and hitherto unreported 1-aryl-2-iminoazepanes. The cyclization reaction involves good to high yields and short reaction times, and represents a novel application of PPA esters in heterocyclic
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Published 14 Sep 2016

Bridgehead vicinal diallylation of norbornene derivatives and extension to propellane derivatives via ring-closing metathesis

  • Sambasivarao Kotha and
  • Rama Gunta

Beilstein J. Org. Chem. 2016, 12, 1877–1883, doi:10.3762/bjoc.12.177

Graphical Abstract
  • dienophile [6][7][8]. Cage compounds with interesting applications have been assembled by a cyclization reaction starting with suitably functionalized norbornene derivatives [9][10][11]. Moreover, the norbornene unit induces a hairpin-like architecture when it is incorporated into a peptide chain. This
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Published 22 Aug 2016

Synthesis of 2,1-benzisoxazole-3(1H)-ones by base-mediated photochemical N–O bond-forming cyclization of 2-azidobenzoic acids

  • Daria Yu. Dzhons and
  • Andrei V. Budruev

Beilstein J. Org. Chem. 2016, 12, 874–881, doi:10.3762/bjoc.12.86

Graphical Abstract
  • 2,1-benzisoxazole-3(1H)-ones is reported. The optimization and scope of this cyclization reaction is discussed. It is shown that an essential step of the ring closure of 2-azidobenzoic acids is the formation and photolysis of 2-azidobenzoate anions. Keywords: aryl azides; azepinones; 2,1
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Published 04 May 2016

Cascade alkylarylation of substituted N-allylbenzamides for the construction of dihydroisoquinolin-1(2H)-ones and isoquinoline-1,3(2H,4H)-diones

  • Ping Qian,
  • Bingnan Du,
  • Wei Jiao,
  • Haibo Mei,
  • Jianlin Han and
  • Yi Pan

Beilstein J. Org. Chem. 2016, 12, 301–308, doi:10.3762/bjoc.12.32

Graphical Abstract
  • substrate, the cyclization reaction proceeded smoothly (Scheme 1c). Herein, we report a metal-free cascade 1,2-alkyarylation of substituted N-allylbenzamides with alkanes affording 4-alkyl-substituted dihydroisoquinoline-1(2H)-ones as the product. Results and Discussion Initially, we selected N-methyl-N-(2
  • corresponding products (5ae1–5ae5) with 42% total yield. To extend the synthetic utility of this radical cyclization reaction, N-methacryloyl-N-methylbenzamide derivatives 6 were then tried as substrates for this reaction (Scheme 4). It should be mentioned that only a few radical precursors, such as the TMSCF3
  • radical cyclization reaction was proposed (Scheme 6). Initially, DTBP undergoes homolytic cleavage to form the tert-butoxy radical A, which reacts with cyclohexane (2a) affording intermediate B. Then, intermediate B adds to N-methyl-N-(2-methylallyl)benzamide (4a), giving radical intermediate C
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Published 17 Feb 2016

Facile synthesis of 4H-chromene derivatives via base-mediated annulation of ortho-hydroxychalcones and 2-bromoallyl sulfones

  • Srinivas Thadkapally,
  • Athira C. Kunjachan and
  • Rajeev S. Menon

Beilstein J. Org. Chem. 2016, 12, 16–21, doi:10.3762/bjoc.12.3

Graphical Abstract
  • salicylaldehyde and Cs2CO3 and d) reaction of 2a with Cs2CO3. Base-mediated cyclization reaction of o-hydroxychalcone 7a and 2-bromoallyl sulfone 2a. Preparation of ortho-hydroxychalcones 7a–i. Synthesis of 4H-chromenes via base-mediated reactions of 7a–i and 2a,b. Reaction conditions: 7a–i (0.25 mmol), 2a,b
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Published 06 Jan 2016

A new approach to ferrocene derived alkenes via copper-catalyzed olefination

  • Vasily M. Muzalevskiy,
  • Aleksei V. Shastin,
  • Alexandra D. Demidovich,
  • Namiq G. Shikhaliev,
  • Abel M. Magerramov,
  • Victor N. Khrustalev,
  • Rustem D. Rakhimov,
  • Sergey Z. Vatsadze and
  • Valentine G. Nenajdenko

Beilstein J. Org. Chem. 2015, 11, 2072–2078, doi:10.3762/bjoc.11.223

Graphical Abstract
  • we assume that the radical-ions formed after the first electron transfer would enter the intramolecular cyclization reaction involving the second adjacent double bond with subsequent electropolymerization. The latter is confirmed by a pronounced decrease in current values (3–4 times) as compared to
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Published 03 Nov 2015

Mechanism, kinetics and selectivity of selenocyclization of 5-alkenylhydantoins: an experimental and computational study

  • Biljana M. Šmit,
  • Radoslav Z. Pavlović,
  • Dejan A. Milenković and
  • Zoran S. Marković

Beilstein J. Org. Chem. 2015, 11, 1865–1875, doi:10.3762/bjoc.11.200

Graphical Abstract
  • theory (DFT) methods. The pathways of the reaction are investigated in detail. There are two regioselective pathways related to 5-exo and 6-endo products. Theoretical calculations and the monitoring of the cyclization reaction using 1H NMR spectroscopy are in a good agreement with the proposed mechanism
  • spectrometer in CD3CN as a solvent. Tetramethylsilane (δ = 0.0 ppm) was used as internal reference and chemical shifts are reported to the nearest 0.01 ppm. 1H NMR measurements of the cyclization reaction of hydantoin 1 (4.7 mg, 0.024 mmol, 1 equiv) with PhSeCl (5.0 mg, 0.026 mmol, 1.1 equiv) in the presence
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Published 07 Oct 2015

Recent applications of ring-rearrangement metathesis in organic synthesis

  • Sambasivarao Kotha,
  • Milind Meshram,
  • Priti Khedkar,
  • Shaibal Banerjee and
  • Deepak Deodhar

Beilstein J. Org. Chem. 2015, 11, 1833–1864, doi:10.3762/bjoc.11.199

Graphical Abstract
  • assemble the erythrina skeleton. To this end, they have identified cyclobutene derivative 48 as a useful synthone for RRM. The cyclobutene derivative 46 has been extended via Grignard addition followed by cyclization reaction. Later, cyclobutene derivative 48 was treated with catalyst 1 in the presence of
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Published 07 Oct 2015

Pyridinoacridine alkaloids of marine origin: NMR and MS spectral data, synthesis, biosynthesis and biological activity

  • Louis P. Sandjo,
  • Victor Kuete and
  • Maique W. Biavatti

Beilstein J. Org. Chem. 2015, 11, 1667–1699, doi:10.3762/bjoc.11.183

Graphical Abstract
  • ), styelsamine B (4), demethyldeoxyamphimedine (9), and subarine (37) was strategically achieved with up to five steps. Synthesis of styelsamine B (4) and cystodytin J (1) The first route showed the total synthesis of styelsamine B via oxidation, Michael addition, condensation and cyclization reaction steps
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Published 18 Sep 2015

Design and synthesis of polycyclic sulfones via Diels–Alder reaction and ring-rearrangement metathesis as key steps

  • Sambasivarao Kotha and
  • Rama Gunta

Beilstein J. Org. Chem. 2015, 11, 1373–1378, doi:10.3762/bjoc.11.148

Graphical Abstract
  • methanesulfonyl chloride in the presence of triethylamine as a base to obtain the dimesylate 3 (89%). Next, compound 3 was subjected to a cyclization reaction by treating with sodium sulfide nonahydrate (Na2S·9H2O) using 20% Aliquat® 336 as a phase–transfer catalyst (PTC) to produce the known sulfide 5 (83%) [31
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Published 06 Aug 2015

Selected synthetic strategies to cyclophanes

  • Sambasivarao Kotha,
  • Mukesh E. Shirbhate and
  • Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

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Published 29 Jul 2015

Radical-mediated dehydrative preparation of cyclic imides using (NH4)2S2O8–DMSO: application to the synthesis of vernakalant

  • Dnyaneshwar N. Garad,
  • Subhash D. Tanpure and
  • Santosh B. Mhaske

Beilstein J. Org. Chem. 2015, 11, 1008–1016, doi:10.3762/bjoc.11.113

Graphical Abstract
  • 1 from succinanilic acid (2), we observed dehydrative cyclization to furnish N-phenylsuccinimide (3) instead of the expected product 1 (Scheme 1). We were curious to find the actual reagents responsible for this serendipitous facile transformation. We found that the cyclization reaction works in the
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Published 12 Jun 2015

DBU-promoted carboxylative cyclization of o-hydroxy- and o-acetamidoacetophenone

  • Wen-Zhen Zhang,
  • Si Liu and
  • Xiao-Bing Lu

Beilstein J. Org. Chem. 2015, 11, 906–912, doi:10.3762/bjoc.11.102

Graphical Abstract
  • the 2H-chromen-2-one product (Table 2, entries 2 and 4). o-Hydroxyacetophenone bearing electron-donating alkyl and ether groups, or electron-withdrawing fluoro and bromo groups undergoes the carboxylative cyclization reaction smoothly, affording the corresponding 4-butoxy-2H-chromen-2-ones 2b–2f in
  • the carboxylative cyclization reaction to furnish the tricyclic product 2h in moderate yield (Table 2, entry 8). With the successful DBU-promoted carboxylative cyclization of o-hydroxyacetophenone at hand, we then extended this strategy to o-acetamidoacetophenone to synthesize 4-hydroxy-2(1H
  • )-quinolinone (Table 3). Using 4 equivalents DBU as base in DMSO at 80 °C, o-acetamidoacetophenone (3a) underwent the carboxylative cyclization reaction to provide 3-acetyl-4-methoxy-2(1H)-quinolinones 4a and 5a (Table 3, entry 1). Noteworthy, the acyl group was no longer bound to nitrogen in the product, which
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Published 29 May 2015

Gold-catalyzed formation of pyrrolo- and indolo-oxazin-1-one derivatives: The key structure of some marine natural products

  • Sultan Taskaya,
  • Nurettin Menges and
  • Metin Balci

Beilstein J. Org. Chem. 2015, 11, 897–905, doi:10.3762/bjoc.11.101

Graphical Abstract
  • into 3,4-dihydropyrrolo- and indolo-oxazin-1-one derivatives by a gold(III)-catalyzed cyclization reaction. Some of the products underwent TFA-catalyzed double bond isomerization and some did not. Cyclization reactions in the presence of alcohol catalyzed by Au(I) resulted in the formation of
  • atom-economic process using a gold-catalyzed alkyne cyclization reaction as the key step. Pyrrole and indole, bearing one (substituted) propargyl and carboxy group was initially designed as model substrate for the construction of 6 and 7. Gold-catalyzed intramolecular cyclization of enyene carboxylic
  • structure 6 or 7 was not formed. After failure of the cyclization reaction of 13 with AuCl3, even in water-free solvents, we turned our attention to the construction of the pyrrolo-oxazin-1-one skeleton with the corresponding acid 15. For this purpose, the propargyl ester 13 was first hydrolyzed with K2CO3
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Published 28 May 2015

Direct access to pyrido/pyrrolo[2,1-b]quinazolin-9(1H)-ones through silver-mediated intramolecular alkyne hydroamination reactions

  • Hengshuai Wang,
  • Shengchao Jiao,
  • Kerong Chen,
  • Xu Zhang,
  • Linxiang Zhao,
  • Dan Liu,
  • Yu Zhou and
  • Hong Liu

Beilstein J. Org. Chem. 2015, 11, 416–424, doi:10.3762/bjoc.11.47

Graphical Abstract
  • in a sealed tube under argon protection at 80 °C for 3 h (Table 1, entry 3). To evaluate the scope of the proposed silver-catalyzed intramolecular hydroamination cyclization reaction, we investigated its tolerance by probing changes in the substituted 2-(4-pentynyl)-4(3H)-quinazolinone (6A) under the
  • cyclization reaction, and the expected products 9A–L were obtained in good to excellent yields (80–93%, Table 3, entries 1–12). Based on the results of the present studies, we propose a plausible mechanism for the transformation. As depicted in Scheme 2, the intramolecular cyclization is initiated by the
  • through an AgOTf-catalyzed intramolecular alkyne hydroamination cyclization reaction. The methodology is applicable to a wide scope of substrates and generates a series of fused quinazolinone heterocycles in good to excellent yields. It lends itself an alternative method to the construction of innovative
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Published 30 Mar 2015

Azirinium ylides from α-diazoketones and 2H-azirines on the route to 2H-1,4-oxazines: three-membered ring opening vs 1,5-cyclization

  • Nikolai V. Rostovskii,
  • Mikhail S. Novikov,
  • Alexander F. Khlebnikov,
  • Galina L. Starova and
  • Margarita S. Avdontseva

Beilstein J. Org. Chem. 2015, 11, 302–312, doi:10.3762/bjoc.11.35

Graphical Abstract
  • -azabuta-1,3-dienes which transform back to the oxazines in the dark at room temperature. The rate of the reverse cyclization reaction increases with increasing electron-withdrawing ability of C1-substituent in 2-azabuta-1,3-diene. X-ray crystal structure of azadiene 3e. X-ray crystal structures of
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Published 02 Mar 2015
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