- Organocatalytic Enantioselective Michael-Aldol[3+2] Annulation for the Synthesis of Nitro-Methanobenzo[7] annulenes
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We report an enantioselective Michael-Aldol[3+2] annulation between 2-alkyl-3-hydroxynaphthalene-1,4-diones and nitroalkenes using a bifunctional thiourea catalyst, and a series of nitro-methanobenzo[7]annulenes with potential biological activities were synthesized in good yields with excellent enantio- and diastereoselectivities. A gram-scale synthesis and further transformation of the product demonstrated the synthetic value of this reaction.
- Liu, Jin-Yu,Zhang, Xiao-Hai,Zhang, Yang
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supporting information
p. 5008 - 5011
(2021/09/28)
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- Access to C5-Alkylated Indolines/Indoles via Michael-Type Friedel-Crafts Alkylation Using Aryl-Nitroolefins
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A straightforward synthetic route toward C5-alkylated indolines/indoles has been developed. The strategy is composed of Zn(OTf)2-catalyzed Friedel-Crafts alkylation of N-benzylindolines with nitroolefins, and a series of diverse indolines was first obtained in up to 99% yield. This reaction provides a direct and practical route to a variety of the C5-alkylated indolines which were also utilized for accessing corresponding indoles. Indoline derivatives with free NH groups could be obtained through an N-deprotection reaction. Moreover, the primary alkyl nitro groups in both indolines and indoles are amenable to further synthetic elaborations, thereby broadening the diversity of the products.
- Ertugrul, Berrak,Kilic, Haydar,Lafzi, Farrokh,Saracoglu, Nurullah
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p. 9018 - 9038
(2018/06/27)
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- Construction of multisubstituted tetrahydropyrans by a domino oxa-michael/tsujia-trost reaction
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Biologically significant tetrahydropyrans (THP) were synthesized by a Tandem oxa-Michael/Tsujia-Trost reaction. Different Michael acceptors were investigated, and optimal results in terms of diastereoselectivities and yields were obtained with nitro olefins. The influence of the reaction parameters, substrate patterns, and type of metal counterions on the yield and stereochemical outcome of this process is discussed, and an explanation for the observed stereoselectivities is proposed.
- Wang, Liang,Menche, Dirk
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p. 10811 - 10823
(2013/02/22)
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- Unexpected course of [2+3] cycloaddition of 2-nitropropene to (Z)-C,N-diphenylnitrone
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The [2+3] cycloaddition of 2-nitropropene to (Z)-C,N-diphenylnitrone leads to 3,4-trans-2,3-diphenyl-4-nitro-4-methyl- and 3,5-trans-2,3-diphenyl-5-nitro- 5-methylisoxazolidines as primary reaction products. This, however, is not the only pathway of 2-nitropropene conversion. In the reaction conditions, the nitroalkene also undergoes isomerisation and the resulting trans- and cis-1-nitropropenes yield respective stereoisomeric 2,3-diphenyl-4-nitro-5- methylisoxazolidines in the reaction with (Z)-C,N-diphenylnitrone.
- Jasinski, Radomir,Mikulska, Maria,Baranski, Andrzej
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body text
p. 41 - 45
(2012/04/23)
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- Concise synthesis of tetrahydropyrans by a tandem oxa-michael/tsuji-trost reaction
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A novel domino sequence facilitates the rapid assembly of polysubstituted tetrahydropyrans. The one-pot relay process generates up to three new stereogenic centers, including a tetrasubstituted carbon center, in a highly concise and convergent fashion from simple starting materials. Copyright
- Wang, Liang,Li, Pengfei,Menche, Dirk
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supporting information; experimental part
p. 9270 - 9273
(2011/02/28)
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- METHOD FOR ELIMINATING COLOR FORMING IMPURITIES FROM NITRO COMPOUNDS
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A method for stabilizing nitro compounds against discoloration. The method comprises reacting nitro compounds containing color-forming impurities with nitric acid, neutralizing and washing the product, and distilling therefrom purified nitro compounds.
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Page/Page column 8
(2009/12/02)
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- Novel synthesis of α-nitroalkenes from nitroalkanes via halogenation of intermediate N,N-bis(silyloxy)enamines
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An approach to conjugated nitroalkenes via oxidation of N,N-bis(silyloxy)enamines with bromine or iodine in the presence of tetra-n-butylammonium acetate is described. The acetate ion plays a key role by acting as a mild desilylating reagent. This new strategy allows the synthesis of α-nitroalkenes from the corresponding nitroalkanes.
- Kunetsky, Roman A.,Dilman, Alexander D.,Struchkova, Marina I.,Tartakovsky, Vladimir A.,Ioffe, Sema L.
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p. 5203 - 5205
(2007/10/03)
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- Propylene oxidation by palladium nitro and nitrato complexes: In situ NMR and IR studies
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The mechanism of the propylene oxidation by Pd(NOn) Cl2-m(CH3CN)2 complexes (n=2,3; m=0,1,2) in chloroform solutions has been studied by 1 and IR spectroscopy. The main reaction products are acetone and 2-nitropropylene, with their ratio depending on the equilibrium existing in the reaction solutions between palladium complexes containing NOn ligands bonded to a palladium atom via either an oxygen or a nitrogen atom. Reactivities of the oxygen bonded nitrato and nitrito complexes are significantly higher than that of the nitrogen bonded nitro complex. Various new organopalladium intermediates have been observed and monitored in situ. A reversible insertion of the coordinated propylene into the Pd-O or Pd-N bonds results in nitrato-, nitrito- and nitropalladation intermediates, which then decompose via a β-hydrogen elimination. Two isomers of the nitritopalladation intermediate have been detected, i.e., a palladium metallacycle and an open ring complex, with the latter being much more reactive towards the β-hydrogen elimination than the former. The decomposition of the nitrato- and nitritopalladation intermediates results in the organometallic precursor of acetone, i.e., an acetonylpalladium complex, and then in acetone itself. On the other hand, the nitropalladation intermediate originates 2-nitropropylene. In the presence of dioxygen, which re-oxidizes the nitrosyl groups, the acetone formation becomes a catalytic reaction with respect to both palladium and nitrogen. Elsevier B.V. All rights reserved.
- Beck, Irene E.,Golovin, Anatoli V.,Likholobov, Vladimir A.,Gusevskaya, Elena V.
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p. 2880 - 2887
(2007/10/03)
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- Kinetics and mechanisms of the gas-phase elimination of 2-substituted primary, secondary and tertiary hydroxy groups in nitroalkanes
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The kinetics of the gas-phase elimination of several 2-substituted primary, secondary and tertiary hydroxy groups in nitroalkanes were determined in a static reaction system over the temperature range 220-400°C and pressure range of 29-235 Torr. The reactions, in seasoned vessels, are homogeneous and unimolecular and obey a first-order rate law. The presence of secondary and tertiary hydroxy substituent at the 2-position of the nitro group in nitroalkanes leads to a retro-aldol type of decomposition. The mechanism may be rationalized in terms of a six-membered cyclic transition state to give the corresponding aldehyde or ketone and the nitroalkane, respectively. However, some of the primary 2-hydroxy groups in nitroalkanes undergo a dehydration process with very limited isomerization to the corresponding alkyl nitrate. The mechanism of dehydration is believed to proceed through a six-membered rather than the already reported four-membered cyclic transition state to give the nitroalkene and water. In the case of the primary hydroxy substituent in 2-methyl-2-nitro-1-pentanol, the products of elimination are HNO2 gas and 3-hydroxy-2-methyl-1-propene. This reaction is rationalized in terms of a four-membered cyclic transition state type of mechanism. The kinetic and thermodynamic parameters of the hydroxynitroalkane substrates are presented and discussed. Copyright 2004 John Wiley & Sons, Ltd.
- Dominguez, Rosa Maria,Herize, Armando,Rotinov, Alexandra,Alvarez-Aular, Alvaro,Visbal, Gonzalo,Chuchani, Gabriel
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p. 399 - 408
(2007/10/03)
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- CYCLOADDITION DES METHYLAZIDE ET PHENYLAZIDE AU β-NITROSTYRENE ET AU NITROPROPENE HOMOLOGUE
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Phenylazide and methylazide reacts with title olefines and gives two isomeric triazoles without nitro group, and 4-nitro-1,2,3 triazole.The isomerisation of starting alkenes explains the formation of isomeric triazoles.Oxydation of amino-nitro-diazocompounds in equilibrium with 1,2,3 triazolines leads to 4-nitro-1,2,3 triazoles.
- Cailleux, P.,Piet, J. C.,Benhaoua, H.,Carrie, R.
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- Synthesis and serotonin receptor affinities of a series of enantiomers of α-methyltryptamines: Evidence for the binding conformation of tryptamines at serotonin 5-HT(1B) receptors
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A procedure for the preparation of optically pure α-methyltryptamines (AMTs) from substituted indoles was developed. The key step in the sequence was the reductive amination of substituted indole-2-propanones with the commercially available pure enantiomers of α-methylbenzylamine, followed by the chromatographic separation of the resulting pair of diastereomeric amines by preparative centrifugal (Chromatotron) chromatography. Catalytic N-debenzylation then afforded the pure AMT enantiomers. Optical purity was established by chiral HPLC analysis of the 2-naphthoylamide derivatives. An improved procedure for the preparation of indole-2-propranone was also developed. To probe structure-activity relationships of serotonin receptors, affinities of the α-methyltryptamine enantiomers were then measured at the 5-HT2 antagonist receptor subtype, with displacement of [3H]ketanserin, and were estimated at the 5-HT(1B) receptor, with displacement of [3H]serotonin, respectively, in rat frontal cortex homogenates. Enantioselectivity at the receptor subtypes varied, depending on aromatic substituents. For a 5-hydroxy or 5-methoxy, the S enantiomer had higher affinity or was equipotent to the R enantiomer. This selectivity at [3H]serotonin binding sites was reversed for 4-oxygenated α-methyltryptamines, where a 4-hydroxy or 4-methoxy did not enhance affinity over the unsubstituted compounds. These results can be explained, for the [3H]serotonin displacement data, if the binding conformation is one where the ethylamine side chain is trans and lying in a plane perpendicular to the indole ring plane.
- Nichols,Lloyd,Johnson,Hoffman
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p. 1406 - 1412
(2007/10/02)
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- Laser-powered Homogeneous and Heterogeneous Pyrolysis of 2-Nitropropane
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The pyrolysis of 2-nitropropane has been studied under both homogeneous conditions (using a continuous-wawe CO2 laser and sensitized by sulphur hexafluoride) and heterogeneous conditions (pulsed pyrolysis) at temperatures in the range 820-1210 K.A comparison of both decompositions is aided by the determination of spatial temperature profiles and the effective temperature in the laserdriven reaction by using calculations of the temperature distribution, thermocouple techniques and elimination of ethyl acetate as a 'chemical thermometer'.The main process in the laser-driven decomposition is the clean decomposition into propene and nitrous acid occuring via C-N bond fission.In heterogeneous pyrolysis additional products such as 2-nitropropene, acetonitrile and acetone are formed.The high yield of 2-nitropropene at 820 K indicates a unique route to this compound.
- Pola, Josef,Farkacova, Marta,Kubat, Pavel,Trka, Antonin
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p. 1499 - 1506
(2007/10/02)
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- Preparation of nitro-olefins
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A process for the preparation of nitro-olefins comprising reacting a compound of the formula STR1 where R and R1 can be hydrogen, alkyl of 1-20 carbon atoms or phenyl, with an aldehyde acceptor selected from the group consisting of alkylene polyols or aromatic polyols, in the presence of an alkaline catalyst or a Lewis acid catalyst.
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