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Search for "β-nitrostyrene" in Full Text gives 38 result(s) in Beilstein Journal of Organic Chemistry.

Supported bifunctional thioureas as recoverable and reusable catalysts for enantioselective nitro-Michael reactions

  • José M. Andrés,
  • Miriam Ceballos,
  • Alicia Maestro,
  • Isabel Sanz and
  • Rafael Pedrosa

Beilstein J. Org. Chem. 2016, 12, 628–635, doi:10.3762/bjoc.12.61

Graphical Abstract
  • bifunctional thioureas on sulfonylpolystyrene resins has been studied in the nitro-Michael addition of different nucleophiles to trans-β-nitrostyrene derivatives. The activity of the catalysts depends on the length of the tether linking the chiral thiourea to the polymer. The best results were obtained with
  • reactions of 4-chloro- (1b) and 4-fluoronitrostyrene (1c) were very similar than those obtained in the reaction with β-nitrostyrene (1a), maintaining the yield and the enantioselectivity, although 1c reacted slowly within 48 h (compare entries 1 and 2 in Table 2 versus entry 5 in Table 1), but the less
  • . The results obtained with the described catalysts are similar to those previously reported by using bottom-up synthesized materials prepared by co-polymerization of monomeric thioureas as organocatalysts [29]. Catalyst V has been also used in the addition of α-nitrocyclohexanone (6a) to β-nitrostyrene
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Published 01 Apr 2016

The aminoindanol core as a key scaffold in bifunctional organocatalysts

  • Isaac G. Sonsona,
  • Eugenia Marqués-López and
  • Raquel P. Herrera

Beilstein J. Org. Chem. 2016, 12, 505–523, doi:10.3762/bjoc.12.50

Graphical Abstract
  • to explain the sense of the asymmetric induction observed in the reaction, some experiments with structurally modified catalysts (4' and 4'') were carried out. The results obtained using indole (2a) and β-nitrostyrene (3a) supported the importance of the hydroxy group, since low yield and selectivity
  • catalyst, in its Z form, which is stabilized due to an intramolecular hydrogen bond (Scheme 14). In 2012, Dong and co-workers studied the catalytic activity of several β-amino alcohol-based squaramide organocatalysts involved in the Michael addition of acetylacetone (36a) to β-nitrostyrene (3a) in
  • catalyst, the hydroxy group of the squaramide 43 was methylated (43'). Its catalytic activity was tested in the reaction of acetylacetone (36a) and β-nitrostyrene (3a), leading to very low enantiomeric excess (24% ee). This fact suggested the important role played by the hydroxy group in the activation and
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Published 14 Mar 2016

(Thio)urea-mediated synthesis of functionalized six-membered rings with multiple chiral centers

  • Giorgos Koutoulogenis,
  • Nikolaos Kaplaneris and
  • Christoforos G. Kokotos

Beilstein J. Org. Chem. 2016, 12, 462–495, doi:10.3762/bjoc.12.48

Graphical Abstract
  • substrates were tested and the products were isolated in good yields, moderate diasteroselectivities and excellent enantioselectivities. To expand the utility of the developed process, Zhao and co-workers performed the reaction with trans-β-nitrostyrene in gram scale isolating the desired product in 74
  • tandem Michael addition of γ,δ-unsaturated-β-ketoesters 114 to trans-β-nitrostyrene 115 which produced tetrasubstituted cyclohexenols 116 and 117 utilizing Takemoto’s catalyst 77 (Scheme 37) [56]. In a paper that described in more detail the transformation, the authors showed that the substitution of the
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Published 10 Mar 2016

Organocatalytic and enantioselective Michael reaction between α-nitroesters and nitroalkenes. Syn/anti-selectivity control using catalysts with the same absolute backbone chirality

  • Jose I. Martínez,
  • Uxue Uria,
  • Maria Muñiz,
  • Efraím Reyes,
  • Luisa Carrillo and
  • Jose L. Vicario

Beilstein J. Org. Chem. 2015, 11, 2577–2583, doi:10.3762/bjoc.11.277

Graphical Abstract
  • . Results and Discussion We started our work by first applying the conditions optimized for our recently reported cascade process to the reaction between ethyl 2-nitropropanoate (1a) and β-nitrostyrene (2a). As it can be seen in Scheme 2, the use of catalyst 4 led to the formation of the syn-diastereoisomer
  • consequence of the very likely decomposition of these rather unstable nitroalkene reagents. Finally, we also surveyed the use of a nitroacetate donor with a bulkier substituent such as 1b which also performed very well in the reaction with trans-β-nitrostyrene (2a), para-methoxy-trans-β-nitrostyrene (2e) or
  • para-bromo-trans-β-nitrostyrene (2k), yielding the corresponding products syn-3o–q with comparable results to those obtained with Michael donor 1a (Table 1, entries 15–17). Next, we proceeded to evaluate the scope of the reaction leading to diastereomeric adducts anti-3 (Table 2) using bifunctional
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Published 14 Dec 2015

Cathodic hydrodimerization of nitroolefins

  • Michael Weßling and
  • Hans J. Schäfer

Beilstein J. Org. Chem. 2015, 11, 1163–1174, doi:10.3762/bjoc.11.131

Graphical Abstract
  • in [6][7][8]. There have been reports on the reductive dimerization of nitro alkenes prior to 1991. 1,4-Dinitro-2,3-diphenylbutane (3) has been obtained in less than 20% yield in the catalytic hydrogenation of β-nitrostyrene (4) [11]. Hydrodimerization of 4 was observed in enzymatic reduction [12
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Published 14 Jul 2015

New hydrogen-bonding organocatalysts: Chiral cyclophosphazanes and phosphorus amides as catalysts for asymmetric Michael additions

  • Helge Klare,
  • Jörg M. Neudörfl and
  • Bernd Goldfuss

Beilstein J. Org. Chem. 2014, 10, 224–236, doi:10.3762/bjoc.10.18

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  • catalysts based on rigid cis-PV-cyclodiphosphazane amides of N1,N1-dimethylcyclohexane-1,2-diamine have been developed. Employed in the asymmetric Michael addition of 2-hydroxynaphthoquinone to β-nitrostyrene, the open-chain 9-epi-aminochinchona-based phosphorus amides show a high catalytic activity with
  • defined geometry. Introducing a new motif, Shea et al. have synthesized achiral tridentate (thio)phosphorus triamides and assessed their catalytic activity relative to the established (m-(CF3)2-Ph)2thiourea [18]. In the Friedel–Crafts reaction of N-methylindole with β-nitrostyrene and the Baylis–Hillman
  • of 2-hydroxynaphthoquinone to β-nitrostyrene as a test reaction. Results and Discussion Computational assessment of HB strengths To determine the relative strength of the hydrogen bonding, the interaction between unsubstituted HB motifs and nitrobenzene (I–IV, Figure 2) was computed. In the
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Published 21 Jan 2014

Synthetic scope and DFT analysis of the chiral binap–gold(I) complex-catalyzed 1,3-dipolar cycloaddition of azlactones with alkenes

  • María Martín-Rodríguez,
  • Luis M. Castelló,
  • Carmen Nájera,
  • José M. Sansano,
  • Olatz Larrañaga,
  • Abel de Cózar and
  • Fernando P. Cossío

Beilstein J. Org. Chem. 2013, 9, 2422–2433, doi:10.3762/bjoc.9.280

Graphical Abstract
  • irradiation was not as effective as occurred in the reaction with NMM. For example, the purification of the crude reaction mixture of the cycloaddition of 7aa with β-nitrostyrene afforded an overall poor yield (~28%) of a complex 4:15:10 mixture of three compounds (16, 17, and 18) (Scheme 9) [44]. The desired
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Published 11 Nov 2013

Sequential Diels–Alder/[3,3]-sigmatropic rearrangement reactions of β-nitrostyrene with 3-methyl-1,3-pentadiene

  • Peter A. Wade,
  • Alma Pipic,
  • Matthias Zeller and
  • Panagiota Tsetsakos

Beilstein J. Org. Chem. 2013, 9, 2137–2146, doi:10.3762/bjoc.9.251

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  • Peter A. Wade Alma Pipic Matthias Zeller Panagiota Tsetsakos Department of Chemistry, Drexel University, Philadelphia, PA 19104, U.S.A Department of Chemistry, Youngstown State University, Youngstown, OH, U.S.A 10.3762/bjoc.9.251 Abstract The tin(IV)-catalyzed reaction of β-nitrostyrene with (E
  • formal cycloadducts of (Z)-3-methyl-1,3-pentadiene. A Friedel–Crafts alkylation product from the reaction of the diene, β-nitrostyrene, and toluene was also obtained in 10% yield. The tin(IV)-catalyzed reaction of β-nitrostyrene with (Z)-3-methyl-1,3-pentadiene in dichloromethane afforded four nitronic
  • Discussion Cycloaddition studies The tin(IV) chloride-catalyzed reaction of β-nitrostyrene and an E,Z–mixture of 3-methyl-1,3-pentadiene (1a,b, 70:30, respectively) in dichloromethane solution afforded a series of six Diels–Alder nitronic ester cycloadducts, none of which heavily predominated (Table 1). Only
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Published 17 Oct 2013

Organocatalytic tandem Michael addition reactions: A powerful access to the enantioselective synthesis of functionalized chromenes, thiochromenes and 1,2-dihydroquinolines

  • Chittaranjan Bhanja,
  • Satyaban Jena,
  • Sabita Nayak and
  • Seetaram Mohapatra

Beilstein J. Org. Chem. 2012, 8, 1668–1694, doi:10.3762/bjoc.8.191

Graphical Abstract
  • , respectively, via the generation of a transient ion pair through iminium and imine intermediates. The reaction afforded the corresponding tetrahydroxanthenones 14 in excellent yields (95%) and enantioselectivities (95%) (Scheme 10). 1.2. Reaction of 2-hydroxycinnamaldehydes/2-hydroxy-β-nitrostyrene with
  • for constructing highly functionalized and enantiomerically enriched tetrahydro-6H-benzo[c]chromenes with five stereogenic centers. The reaction involved a domino oxa-Michael–Michael–Michael–aldol condensation of o-hydroxy-β-nitrostyrene 15 and two equivalents of α,β-unsaturated aldehydes in the
  • cascade reaction starts in an analogous manner to that previously mentioned, although the first oxa-Michael step is followed by a second Michael addition to form the chroman unit. A series of α,β-unsaturated aldehydes were reacted with the o-hydroxy-β-nitrostyrene as shown in Scheme 11. Except for the
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Published 04 Oct 2012

Synthesis and evaluation of new guanidine-thiourea organocatalyst for the nitro-Michael reaction: Theoretical studies on mechanism and enantioselectivity

  • Tatyana E. Shubina,
  • Matthias Freund,
  • Sebastian Schenker,
  • Timothy Clark and
  • Svetlana B. Tsogoeva

Beilstein J. Org. Chem. 2012, 8, 1485–1498, doi:10.3762/bjoc.8.168

Graphical Abstract
  • Organic Chemistry I, University of Erlangen-Nuremberg, Henkestraße 42, 91054, Erlangen, Germany 10.3762/bjoc.8.168 Abstract A new guanidine-thiourea organocatalyst has been developed and applied as bifunctional organocatalyst in the Michael addition reaction of diethyl malonate to trans-β-nitrostyrene
  • thiourea moiety and an imidazole group [43][44] on a chiral scaffold, as asymmetric catalysts in the addition of acetone to trans-β-nitrostyrene, have also been reported [44][45][46][47]. Since guanidines [48] are stronger bases than amines and/or imidazole, we were interested in exploring whether
  • . However, guanidine-thiourea 7 gave the product 10 only in racemic form and in moderate yield (62%, Scheme 2). The Michael additions of 2,4-pentanedione and diethylmalonate to trans-β-nitrostyrene were further explored (Scheme 3). The use of guanidine-thiourea 7 at 20 mol % in toluene at room temperature
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Published 07 Sep 2012

A quantitative approach to nucleophilic organocatalysis

  • Herbert Mayr,
  • Sami Lakhdar,
  • Biplab Maji and
  • Armin R. Ofial

Beilstein J. Org. Chem. 2012, 8, 1458–1478, doi:10.3762/bjoc.8.166

Graphical Abstract
  • of the C–C bond. The observation that β-nitrostyrene, a neutral electrophile, also reacts 102 times faster with 33– than with 36 also excludes Coulomb attraction to be the major factor for the high reactivity of 33−. On the other hand, di-tert-butyl azodicarboxylate reacts only six times faster with
  • data in Figure 18 and Figure 19 now explains why the Jørgensen-Hayashi diphenylprolinol trimethylsilyl ether [81], the precursor of 32b, and structurally related pyrrolidines have previously been employed for catalyzing the reactions of aldehydes and ketones with weak electrophiles, such as β
  • -nitrostyrene (E = –13.9) [85] or di-tert-butyl azodicarboxylate (E = –12.2) [86]. The less basic imidazolidinones, which yield the less nucleophilic enamines 32d and 32e, are suitable catalysts for reactions with stronger electrophiles, such as the chlorinating agent 2,3,4,5,6,6-hexachlorocyclohexan-2,4-dien-1
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Published 05 Sep 2012

Combined bead polymerization and Cinchona organocatalyst immobilization by thiol–ene addition

  • Kim A. Fredriksen,
  • Tor E. Kristensen and
  • Tore Hansen

Beilstein J. Org. Chem. 2012, 8, 1126–1133, doi:10.3762/bjoc.8.125

Graphical Abstract
  • also tested in the Michael addition of methyl malonate to trans-β-nitrostyrene (Table 4) [21]. The catalyst gave quantitative yield and excellent enantioselectivity after 3–4 days reaction time. However, the catalyst exhibited poor recycling properties as yields fell sharply after the second reaction
  • determined by HPLC analysis (Chiralpak AD-H, 2% iPrOH in isohexane, 1.0 mL/min): tR = 19.2 min and 26.2 min. General procedure for asymmetric Michael addition of methyl malonate to trans-β-nitrostyrene: trans-β-Nitrostyrene (83.4 mg, 0.56 mmol) and methyl malonate (0.23 g, 1.78 mmol) were dissolved in
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Published 20 Jul 2012

Catalyst-free and solvent-free Michael addition of 1,3-dicarbonyl compounds to nitroalkenes by a grinding method

  • Zong-Bo Xie,
  • Na Wang,
  • Ming-Yu Wu,
  • Ting He,
  • Zhang-Gao Le and
  • Xiao-Qi Yu

Beilstein J. Org. Chem. 2012, 8, 534–538, doi:10.3762/bjoc.8.61

Graphical Abstract
  • [22], a transition-metal-free process for the synthesis of substituted dihydrofurans [23] and a catalyst-free tandem reaction for the synthesis of 5-hydroxy-1,5-dihydro-2H-pyrrol-2-ones in aqueous medium [24]. Recently, when carrying out the reaction of β-nitrostyrene with 1,3-cyclopentanedione under
  • . Results and Discussion In our initial study, equimolar amounts of β-nitrostyrene (1a) and 1,3-cyclopentanedione (2a), as a model reaction (Table 1, entry 1), were mixed and ground in a mortar at room temperature. The mixture became sticky and adhered to the wall of the mortar firmly after a few seconds
  • solvents gave much lower yields. In fact, there are few reports on the Michael addition of β-nitrostyrene and 1,3-cyclopentanedione. Hrnčiar and Čulák performed the same reaction in methanol using sodium methylate as a catalyst; however, only 85% of product 3a was obtained, and a longer reaction time was
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Published 11 Apr 2012
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