- Synthesis of Highly Substituted Phenols and Benzenes with Complete Regiochemical Control
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Substituted phenols are requisite molecules for human health, agriculture, and diverse synthetic materials. We report a chemical synthesis of phenols, including penta-substituted phenols, that accommodates programmable substitution at any position. This method uses a one-step conversion of readily available hydroxypyrone and nitroalkene starting materials to give phenols with complete regiochemical control and in high chemical yield. Additionally, the phenols can be converted into highly and even fully substituted benzenes.
- Zhang, Xiaojie,Beaudry, Christopher M.
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supporting information
p. 6086 - 6090
(2020/08/12)
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- Reaction behaviour of arylamines with nitroalkenes in the presence of bismuth(iii) triflate: An easy access to 2,3-dialkylquinolines
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We report the reaction behaviour of arylamines with nitroalkenes in the presence of bismuth(iii) triflate (10 mol%) and diacetoxyiodobenzene (10 mol%). We obtained 2,3-dialkylquinoline derivatives instead of the expected 3-alkylindole derivatives. The present reaction is an alternative approach for the synthesis of 2,3-dialkylquinoline derivatives under milder conditions. Furthermore, we establish the mechanistic pathway by theoretical calculations using Gaussian 09 software [B3LYP/6-311+G(d,p)], which shows that the conventional aza-Michael reaction is preferred over Michael addition. Aliphatic nitroalkenes behave in a different manner than aromatic nitroalkenes. An aza-Michael adduct gives rise to an imine by the elimination of water which may tautomerize to the corresponding enamine. The resulting imine and enamine intermediates react together to afford the desired quinoline derivatives. This protocol has the advantages of consecutive formation of one C-N and two C-C bonds, high regioselectivity, broad substrate-scope and good yields.
- Ali, Saghir,Gattu, Radhakrishna,Singh, Varun,Mondal, Santa,Khan, Abu T.,Dubey, Gurudutt,Bharatam
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supporting information
p. 1785 - 1793
(2020/03/17)
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- A Nickel-Bisdiamine Porous Organic Polymer as Heterogeneous Chiral Catalyst for Asymmetric Michael Addition to Aliphatic Nitroalkenes
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We report a polystyrene-incorporated chiral nickel(II)-bisdiamine complex, which is accessible on gram-scale. This metal complex functions as a heterogeneous catalyst for the enantioselective Michael addition between malonates and aliphatic nitroalkenes,
- Buendia, Mikkel B.,Kegn?s, S?ren,Kramer, S?ren
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supporting information
p. 5506 - 5512
(2020/10/23)
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- Highly Enantioselective Michael Addition of Dithiomalonates to Nitroolefins Catalyzed by New Bifunctional Chiral Thioureas
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We report a highly efficient asymmetric Michael addition of dithiomalonates to trans -β-nitroole?ns catalyzed by versatile cinchona-based bifunctional thioureas, which provides the corresponding adducts in high yields (up to 92%) and with excellent enanti
- Yuan, Jia-Ni,Liu, Hui-Xia,Tian, Qin-Qin,Ji, Nan,Shen, Kuo,He, Wei
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supporting information
p. 2577 - 2586
(2018/05/03)
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- An Asymmetric Vinylogous Michael Cascade of Silyl Glyoximide, Vinyl Grignard, and Nitroalkenes via Long Range Stereoinduction
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A diastereoselective auxiliary-mediated vinylation/[1,2]-Brook rearrangement/vinylogous Michael cascade of silyl glyoximide, vinylmagnesium bromide, and nitroalkenes is described. The reaction occurs with complete regio- and diastereocontrol in good yield. The diastereoselectivity is induced by a rare instance of 1,7-chirality transfer that is hypothesized to arise from a trans-multihetero-decalin transition state. (Chemical Equation).
- Boyce, Gregory R.,Johnson, Jeffrey S.
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p. 1712 - 1717
(2016/03/01)
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- Organocatalytic Enantioselective Transfer Hydrogenation of β-Amino Nitroolefins
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The asymmetric organocatalytic transfer hydrogenation of β-acylamino and β-tert-butyloxycarbonylamino nitroolefins has been successfully realised in excellent enantioselectivities and yields (up to >99% ee, 97% yield) with a simple thiourea catalyst and a Hantzsch ester as hydrogen source, giving a direct access to enantiomerically pure β-amino nitroalkanes. (Figure presented.).
- Ferraro, Antonino,Bernardi, Luca,Fochi, Mariafrancesca
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supporting information
p. 1561 - 1565
(2016/10/13)
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- Asymmetric addition of cyanide to β-nitroalkenes catalysed by chiral salen complexes of Titanium(IV) and Vanadium(V)
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Structurally well-defined bimetallic titanium(IV) (salen) and monometallic vanadium(V) (salen) complexes have been used as catalysts for the asymmetric addition of trimethylsilyl cyanide to β-nitroalkenes to produce chiral nitronitriles with ee values in the range of 79-89% and conversions up to 100% at 0°C. The reaction conditions (solvent, temperature, time and vanadium complex counter-ion) were optimised, and it was shown that the catalyst loading could be significantly reduced (20 to 2mol%) and the reaction temperature increased (-40 to 0°C) compared to previous studies that used an insitu prepared catalyst. The results are compared and contrasted with previous results obtained by using the same catalysts for the asymmetric addition of trimethylsilyl cyanide to aldehydes, and a transition-state structure for the asymmetric addition of trimethylsilyl cyanide to nitroalkenes is proposed to account for the observed stereochemistry.
- North, Michael,Watson, James M.
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p. 2405 - 2409
(2013/08/23)
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- Asymmetric N-heterocyclic carbene catalyzed addition of enals to nitroalkenes: Controlling stereochemistry via the homoenolate reactivity pathway to access δ-lactams
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An asymmetric intermolecular reaction between enals and nitroalkenes to yield δ-nitroesters has been developed, catalyzed by a novel chiral N-heterocyclic carbene. Key to this work was the development of a catalyst that favors the δ-nitroester pathway over the established Stetter pathway. The reaction proceeds in high stereoselectivity and affords the previously unreported syn diastereomer. We also report an operationally facile two-step, one-pot procedure for the synthesis of δ-lactams.
- White, Nicholas A.,Dirocco, Daniel A.,Rovis, Tomislav
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supporting information
p. 8504 - 8507
(2013/07/19)
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- Catalytic asymmetric intermolecular stetter reaction of enals with nitroalkenes: Enhancement of catalytic efficiency through bifunctional additives
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An asymmetric intermolecular Stetter reaction of enals with nitroalkenes catalyzed by chiral N-heterocyclic carbenes has been developed. The reaction rate and efficiency are profoundly impacted by the presence of catechol. The reaction proceeds with high selectivities and affords good yields of the Stetter product. Internal redox products were not observed despite of the protic conditions. The impact of catechol has been found to be general, facilitating far lower catalyst loadings than were previously achievable.
- Dirocco, Daniel A.,Rovis, Tomislav
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supporting information; experimental part
p. 10402 - 10405
(2011/08/22)
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- Diastereo- and enantioselective synthesis of vicinal amino alcohols by oxa Michael addition of N-formylnorephedrine to nitro alkenes
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The first intermolecular asymmetric oxa Michael additions with removable chirality information within the hydroxide source are reported. As enantiopure oxygen nucleophile functioning as chiral hydroxide equivalent N-formylnorephedrine (7) was used and conjugate additions to aliphatic (E)-nitro alkenes 2a-j were carned out in good yields (35-87%) and excellent diastereomeric excesses (de = 94-≥98%). After reduction of the nitro group and protection of the amino function (11a-h, 73-87%, both steps), the cleavage of the auxiliary occurred without epimerisation (69-99%) using Na/NH3. The Boc-protected 2-amino alcohols 12a-h could be obtained in good overall yields (30-58 %, four steps) and excellent diastereomeric and enantiomeric excesses (de, ee = 94-≥98%). Transition states explaining the overall stereochemical outcome are presented based on the absolute configuration determined by X-ray structure analysis on 8b.
- Enders, Dieter,Haertwig, Andreas,Raabe, Gerhard,Runsink, Jan
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p. 1771 - 1792
(2007/10/03)
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