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Search for "cyclopropane" in Full Text gives 137 result(s) in Beilstein Journal of Organic Chemistry.

Lanostane- and cycloartane-type triterpenoids from Abies balsamea oleoresin

  • Serge Lavoie,
  • Charles Gauthier,
  • Jean Legault,
  • Sylvain Mercier,
  • Vakhtang Mshvildadze and
  • André Pichette

Beilstein J. Org. Chem. 2013, 9, 1333–1339, doi:10.3762/bjoc.9.150

Graphical Abstract
  • quaternary carbons, including those at δC 170.8 and 207.6 representing carboxylic and ketone carbonyls, respectively (Table 1). The 1H NMR spectrum showed two doublets at δH 0.35 (J = 3.9 Hz) and 0.52 (J = 3.9 Hz) characteristic of a cyclopropane ring (Table 2), suggesting that 4 is a member of the
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Published 04 Jul 2013

Interplay of ortho- with spiro-cyclisation during iminyl radical closures onto arenes and heteroarenes

  • Roy T. McBurney and
  • John C. Walton

Beilstein J. Org. Chem. 2013, 9, 1083–1092, doi:10.3762/bjoc.9.120

Graphical Abstract
  • oxime carbonate, plus 1 equiv of MAP, in t-BuPh or cyclopropane solvent, were irradiated with a 500 W unfiltered Hg lamp directly in the spectrometer resonant cavity. The spectrum obtained from precursor 1f (Figure 2) shows a central 1:1:1 triplet from iminyl radical 5f together with a second species
  • saddle points by frequency calculations. The experimental kinetic and spectroscopic data was all obtained in the nonpolar hydrocarbon solvents t-BuPh or cyclopropane. Solvent effects, particularly differences in solvation between the neutral reactants and neutral transition states, were therefore
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Published 04 Jun 2013

Study on the total synthesis of velbanamine: Chemoselective dioxygenation of alkenes with PIFA via a stop-and-flow strategy

  • Huili Liu,
  • Kuan Zheng,
  • Xiang Lu,
  • Xiaoxia Wang and
  • Ran Hong

Beilstein J. Org. Chem. 2013, 9, 983–990, doi:10.3762/bjoc.9.113

Graphical Abstract
  • preferentially underwent cyclization to deliver a variety of 3-susbtituted-γ-lactones (25b–d). For comparison, the mCPBA-epoxidation approach in literature always demonstrated that electron-rich alkenes are more reactive leading to the reversal of chemoselectivity [70][71]. A cyclopropane group was also
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Published 23 May 2013

New reactive intermediates in organic chemistry

  • Götz Bucher

Beilstein J. Org. Chem. 2013, 9, 613–614, doi:10.3762/bjoc.9.67

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  • studies. In order to characterise a reactive intermediate, it had to be trapped. Thus, in order to characterise a carbene, for example, one would intercept it with an alkene and isolate the resulting cyclopropane. Using internal quenchers (molecular clocks) providing well-defined competing reactions
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Published 26 Mar 2013

Some aspects of radical chemistry in the assembly of complex molecular architectures

  • Béatrice Quiclet-Sire and
  • Samir Z. Zard

Beilstein J. Org. Chem. 2013, 9, 557–576, doi:10.3762/bjoc.9.61

Graphical Abstract
  • -arylpiperidines. This strategy is illuminated by the synthetic outline in Scheme 24, where the intermediate radical 124 arising from addition to alkene 123 undergoes a 1,2-aryl shift via cyclopropane 125, a process made irreversible by elimination of a methylsulfonyl radical to give ester 126 [52]. Two new C–C
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Published 18 Mar 2013

The chemistry of bisallenes

  • Henning Hopf and
  • Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

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Published 15 Nov 2012

trans-2-(2,5-Dimethoxy-4-iodophenyl)cyclopropylamine and trans-2-(2,5-dimethoxy-4-bromophenyl)cyclopropylamine as potent agonists for the 5-HT2 receptor family

  • Adam Pigott,
  • Stewart Frescas,
  • John D. McCorvy,
  • Xi-Ping Huang,
  • Bryan L. Roth and
  • David E. Nichols

Beilstein J. Org. Chem. 2012, 8, 1705–1709, doi:10.3762/bjoc.8.194

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  • successful in leading to compounds with high affinity at the 5-HT2 family of receptors; and the more potent stereoisomer of the cyclopropane analogues had the expected (−)-(1R,2S)-configuration. Screening for affinity at various serotonin receptor subtypes, however, revealed that the cyclopropane congeners
  • properties which are identical, or at least very similar to those of 1a. We had previously characterized the cyclopropane analogue of a hallucinogenic amphetamine known as DOM (2) and had shown that 3 (DMCPA) had high potency both in vitro and in vivo [1][2][3]. We thus considered whether the cyclopropane
  • analogues 4 and 5 might be useful research tools. Accordingly, this report details the synthesis of racemic trans-1-(2,5-dimethoxy-4-iodophenyl)-2-aminocyclopropane (4) and its bromo homolog 5, the resolution of 4 into its (−)-(1R,2S)-enantiomer, as well as the resolution of the cyclopropane carboxylic acid
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Published 08 Oct 2012

Influence of cyclodextrin on the solubility of a classically prepared 2-vinylcyclopropane macromonomer in aqueous solution

  • Helmut Ritter,
  • Jia Cheng and
  • Monir Tabatabai

Beilstein J. Org. Chem. 2012, 8, 1528–1535, doi:10.3762/bjoc.8.173

Graphical Abstract
  • , assignable to the CH of the cyclopropane ring and of the vinyl group, respectively. The FTIR spectrum shows the typical absorption band of ester groups at 1726 cm−1 and the disappearance of the band of primary amino groups; this also proves the successful condensation between 3 and 4. Due to the faintly
  • –2930 (ν CH aliphatic), 1726 (ν C=O of ester), 1639 (ν C=O, amide I), 1545 (δ NH, amide II); 1H NMR (acetone-d6, 300 MHz) δ (ppm) 7.13 (NH), 5.19–4.98 (CH2=CH), 4.11 (COOCH2), 3.85 (CHNH), 2.99 (CH of cyclopropane), 2.82 (CH2NH2), 2.68 (CH2CH2S), 2.47 (CHCO), 2.10 (SCH2CH), 1.61–1.48 (CH2 of
  • cyclopropane), 1.40–1.01 (CH2, CH3). Oligomerization of macromonomer 5 to 6 A solution of 5 (0.7 g) in anhydrous DMF (50 mL) was deaerated with nitrogen bubbling for 1 h. Subsequently, a solution of AIBN (0.42 mg, 2.56 µmol) in anhydrous DMF (0.5 mL) was added. The polymerization was carried out at 65 °C for
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Published 13 Sep 2012

Synthesis of a novel chemotype via sequential metal-catalyzed cycloisomerizations

  • Bo Leng,
  • Stephanie Chichetti,
  • Shun Su,
  • Aaron B. Beeler and
  • John A. Porco Jr.

Beilstein J. Org. Chem. 2012, 8, 1338–1343, doi:10.3762/bjoc.8.153

Graphical Abstract
  • diversity; cycloisomerization; cyclopropane; diyne; isochromene; π-acid; Introduction Our laboratory has an ongoing interest in discovering transformations that afford novel chemotypes [1][2][3][4]. To this end, we have developed a reaction screening paradigm that enables the discovery of new reaction
  • novel polycyclic cyclopropane chemotype. Results and Discussion In an effort to further explore the utility of alkynyl o-benzaldehydes as scaffolds for reaction screening, we designed a focused reaction screen with diynyl benzaldehyde [7] substrate 3. Based on the cycloisomerization/addition reactions
  • toluene [16][17]. The reaction afforded polycyclic cyclopropane 6 in good yield (65%) as a single diastereomer (Scheme 2a). Interestingly, reaction of 3 in the presence of only PtCl2 afforded exclusively isochromene 5 in low yield. Further studies revealed that a multicatalytic reaction system [18
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Published 20 Aug 2012

Chemistry of polyhalogenated nitrobutadienes, 10: Synthesis of highly functionalized heterocycles with a rigid 6-amino-3-azabicyclo[3.1.0]hexane moiety

  • Viktor A. Zapol’skii,
  • Jan C. Namyslo,
  • Armin de Meijere and
  • Dieter E. Kaufmann

Beilstein J. Org. Chem. 2012, 8, 621–628, doi:10.3762/bjoc.8.69

Graphical Abstract
  • , they are attached to isochronous carbon atoms at 59.0 ppm. Furthermore, the proton of the NCH fragment (13C NMR: δ = 47.3 ppm) of the cyclopropane ring appears as a triplet at 1.54 ppm (J = 2.3 Hz). Interestingly, the chemical shift of both of the bridgehead protons is 1.35 ppm (dd, J = 4.2, 2.3 Hz
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Published 23 Apr 2012

Branching out at C-2 of septanosides. Synthesis of 2-deoxy-2-C-alkyl/aryl septanosides from a bromo-oxepine

  • Supriya Dey and
  • Narayanaswamy Jayaraman

Beilstein J. Org. Chem. 2012, 8, 522–527, doi:10.3762/bjoc.8.59

Graphical Abstract
  • common bromo-oxepine intermediate, involving C–C bond forming organometallic reactions. Unsaturated, seven-membered septanoside vinyl bromides or bromo-oxepines, obtained through a ring expansion methodology of the cyclopropane derivatives of oxyglycals, displayed a good reactivity towards several
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Published 10 Apr 2012

Carbamate derivatives and sesquiterpenoids from the South China Sea gorgonian Melitodes squamata

  • Li-Si Huang,
  • Fei He,
  • Hui Huang,
  • Xiao-Yong Zhang and
  • Shu-Hua Qi

Beilstein J. Org. Chem. 2012, 8, 170–176, doi:10.3762/bjoc.8.18

Graphical Abstract
  • well with those previously assigned to the corresponding methyl groups in 8, 9 and other analogues [7][8][9][10][11], which suggests the cis-orientation of the cyclopropane ring [7][8]. The coupling constants (J = 10.0 Hz) between H-5 and H-1/H-6 indicate the trans-relationship of H-5 with H-1 and H-6
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Published 31 Jan 2012

Fluorescent hexaaryl- and hexa-heteroaryl[3]radialenes: Synthesis, structures, and properties

  • Antonio Avellaneda,
  • Courtney A. Hollis,
  • Xin He and
  • Christopher J. Sumby

Beilstein J. Org. Chem. 2012, 8, 71–80, doi:10.3762/bjoc.8.7

Graphical Abstract
  • calculations that show intramolecular charge transfer character in the lowest excited states for hexaaryl[3]radialene derivatives [42]. In the excited state, rotation about the exocyclic bonds of the cyclopropane ring is also possible. The fluorescence emission of the hexaaryl[3]radialenes, coupled with the
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Published 11 Jan 2012

Natural product biosyntheses in cyanobacteria: A treasure trove of unique enzymes

  • Jan-Christoph Kehr,
  • Douglas Gatte Picchi and
  • Elke Dittmann

Beilstein J. Org. Chem. 2011, 7, 1622–1635, doi:10.3762/bjoc.7.191

Graphical Abstract
  • substituent, a beta-methoxy eneone system, and a pyrrolinone ring [41]. The incorporation of the chlorovinylidene group was partially elucidated and predicted to be highly similar to the cyclopropane ring formation of curacin A biosynthesis (Figure 6B) ([42], see below). The enzyme cassette comprises a PKS
  • ) Formation of the trichloroleucyl starter unit of barbamide (7) synthesis through the non-heme iron(II)-dependent halogenases BarB1 and BarB2. B) Formation of cyclopropane and vinyl chloride functional groups in curacin A (9) and jamaicamide A (8) biosynthesis, respectively. The halogenated carbon is
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Published 05 Dec 2011

PEG-embedded KBr3: A recyclable catalyst for multicomponent coupling reaction for the efficient synthesis of functionalized piperidines

  • Sanny Verma,
  • Suman L. Jain and
  • Bir Sain

Beilstein J. Org. Chem. 2011, 7, 1334–1341, doi:10.3762/bjoc.7.157

Graphical Abstract
  • –Alder reactions [22][23], intramolecular Michael reactions [24], intramolecular Mannich reactions onto iminium ions [25], tandem cyclopropane ring-opening/Conia-ene cyclizations [26], and aza-Prins-cyclization [27][28][29], have been reported for the synthesis of piperidines. However, these methods
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Published 28 Sep 2011

Recent developments in gold-catalyzed cycloaddition reactions

  • Fernando López and
  • José L. Mascareñas

Beilstein J. Org. Chem. 2011, 7, 1075–1094, doi:10.3762/bjoc.7.124

Graphical Abstract
  • to those previously proposed by Gagosz, evolves through a cyclopropane fragmentation and protodeauration to afford the products 48 in good yields and excellent stereoselectivities. Based on these and other reports demonstrating the ability of gold(I) and platinum(II) catalysts to induce reactions of
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Published 09 Aug 2011

Recent advances in the gold-catalyzed additions to C–C multiple bonds

  • He Huang,
  • Yu Zhou and
  • Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

Graphical Abstract
  • rearrangement followed by nucleophilic attack of the Boc-protected nitrogen atom. A similar method to synthesize the 2-vinylpiperidin-3-ol 158 by a highly stereoselective gold-catalyzed allene cyclization has been reported (Scheme 27) [72]. The ring expansion of cyclopropane derivatives provides a powerful
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Published 04 Jul 2011

Synthetic applications of gold-catalyzed ring expansions

  • David Garayalde and
  • Cristina Nevado

Beilstein J. Org. Chem. 2011, 7, 767–780, doi:10.3762/bjoc.7.87

Graphical Abstract
  • was gathered which proved the reversible nature of the [3,3]-rearrangement in these cyclopropane probes. However, these transformations proved to be stereospecific in nature through gold-stabilized non-classical carbocations 100 and 100', even if the stereochemical information transfer to the product
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Published 07 Jun 2011

When cyclopropenes meet gold catalysts

  • Frédéric Miege,
  • Christophe Meyer and
  • Janine Cossy

Beilstein J. Org. Chem. 2011, 7, 717–734, doi:10.3762/bjoc.7.82

Graphical Abstract
  • intermediate. Thus, when 3-methyl-3-nonylcyclopropene (8) was treated with a catalytic amount of [(Ph3P)AuNTf2] in the presence of excess styrene, the alkenyl cyclopropane 44, resulting from intermolecular cyclopropanation triggered by the gold carbene 43, was isolated in 72% yield as a 6:1 mixture of cis
  • present. Although no cyclopropane derivative was obtained from this reaction, this transformation has been included in this section because one of the possible mechanisms involves an initial cyclopropanation of the less hindered olefin in 2-methylfuran by the organogold intermediate 51, followed by ring
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Published 30 May 2011

Gold-catalyzed regioselective oxidation of terminal allenes: formation of α-methanesulfonyloxy methyl ketones

  • Yingdong Luo,
  • Guozhu Zhang,
  • Erik S. Hwang,
  • Thomas A. Wilcoxon and
  • Liming Zhang

Beilstein J. Org. Chem. 2011, 7, 596–600, doi:10.3762/bjoc.7.69

Graphical Abstract
  • of note that α-methanesulfonyloxy ketones are versatile synthetic intermediates that can undergo various reactions [27], including substitution [28], elimination [29], the formation of zinc homoenolates [30], the formation of cyclopropane rings under photo-irradiation [31][32][33], the formation of
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Published 11 May 2011

The arene–alkene photocycloaddition

  • Ursula Streit and
  • Christian G. Bochet

Beilstein J. Org. Chem. 2011, 7, 525–542, doi:10.3762/bjoc.7.61

Graphical Abstract
  • has been reported to produce very high yields; however, the lack of regioselectivity in the biradical cyclopropane formation gives the two regioisomers in a ratio of 8:5. Intramolecular reactions The first intramolecular meta photocycloaddition was reported in 1969 by Morrison and Ferree [39]. The
  • can be changed [45]. The linear and angular isomer names are derived from the opening of the cyclopropane ring to afford linearly and angularly fused triquinanes. Asymmetric meta photocycloadditions The meta photocycloaddition has the potential to convert planar (thus achiral) molecules into three
  • the formation of the cyclopropane ring, and both regioisomers are obtained. A similar approach has been published by Morales et al. who observed diastereoselectivity by the introduction of a chiral center α to the aromatic moiety on the tether [49]. Some diastereoselective approaches where the chiral
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Published 28 Apr 2011

Molecular rearrangements of superelectrophiles

  • Douglas A. Klumpp

Beilstein J. Org. Chem. 2011, 7, 346–363, doi:10.3762/bjoc.7.45

Graphical Abstract
  • cyclopropane 55. Subsequent deprotonation and hydride abstractions steps give the final product 52. A similar series of reactions affords the isomeric product 53. An interesting rearrangement and cyclization of an acyl dication has been reported [25]. Ionization of the acid chloride 57 in superacid (FSO3H-SbF5
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Published 23 Mar 2011

Rh-Catalyzed rearrangement of vinylcyclopropane to 1,3-diene units attached to N-heterocycles

  • Franca M. Cordero,
  • Carolina Vurchio,
  • Stefano Cicchi,
  • Armin de Meijere and
  • Alberto Brandi

Beilstein J. Org. Chem. 2011, 7, 298–303, doi:10.3762/bjoc.7.39

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  • so that the various specific cyclopropane transformations can be used as a synthetic tool. In recent years we have shown that 1,3-dipolar cycloadditions of nitrones 1 to the highly strained alkene bicyclopropylidene (BCP, 2) [5][6][7] afford spirocyclopropanated isoxazolidines 3 [8][9] which, on
  • temperatures. This explains the low isolated yields in their syntheses. Analogously to other Rh(I)-catalyzed VCP rearrangements [46][47], the mechanism of the rearrangement likely involves insertion of the Rh(I) species into the cyclopropane ring of the VCP system, with or without incorporation of the double
  • tetrahydrospiro[cyclopropane-1,1’(2’H,6’H)-pyrido[2,1-a]isoquinolin]-2’-one 8. Synthesis of 7’-oxohexahydro spiro[cyclopropane-1-8’(5’H)indolizines] 12. Olefination of spirocyclopropanated heterocyclic ketones 8, 12 and 16. Rearrangement of VCPs 15 and 17 catalyzed by Rh(PPh3)3Cl. Mechanism of the rearrangement
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Published 09 Mar 2011

Effects of anion complexation on the photoreactivity of bisureido- and bisthioureido-substituted dibenzobarrelene derivatives

  • Heiko Ihmels and
  • Jia Luo

Beilstein J. Org. Chem. 2011, 7, 278–289, doi:10.3762/bjoc.7.37

Graphical Abstract
  • signals from each isomer (δ in the range of 8.4–8.7 ppm), and by the integration of the NH and cyclopropane CH signals. Each spectroscopic measurement was repeated twice to ensure the reproducibility. Photometric titration of A) tetrabutylammonium chloride (TBAC) to 1h (c1h = 50 µM) and of B
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Published 04 Mar 2011

Palladium-catalyzed formation of oxazolidinones from biscarbamates: a mechanistic study

  • Benan Kilbas and
  • Metin Balci

Beilstein J. Org. Chem. 2011, 7, 246–253, doi:10.3762/bjoc.7.33

Graphical Abstract
  • groups in 12 and 13 were determined by measuring the coupling constants between the cyclopropane protons. The cyclopropyl proton H-3 in 12 resonates as a triplet with a coupling constant of J = 3.3 Hz, whereas the endo-isomer 13 shows a coupling of 7.9 Hz. Since the cis-coupling in cyclopropane is larger
  • product (Scheme 6). In the case of 8, 16 and 19, the leaving groups, carbamates, are in anti (referred to the cyclopropane ring) positions and, therefore, the palladium complex should approach the double bond in 8, 16, and 19 from the side of the three-membered ring to form a complex. However, the
  • cyclopropyl hydrogens H-6 in 8 and 16 are located over the six-membered ring. These hydrogen atoms block the syn-face of the double bond and may hinder the approach of the palladium complex from the side of the cyclopropane ring. However, the products 9 and 17 were formed under the same reaction conditions in
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Published 24 Feb 2011
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