- Dual Role of Vinyl Sulfonamides as N-Nucleophiles and Michael Acceptors in the Enantioselective Synthesis of Bicyclic δ-Sultams
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A new methodology for the synthesis of enantiomerically enriched bicyclic δ-sultams is described, involving an initial organocatalytic intramolecular aza-Michael reaction of vinyl sulfonamides bearing a conjugated ketone at a remote position. The resulting Michael adducts were then subjected to an intramolecular conjugate addition over the vinyl sulfone moiety, thus rendering the final bicyclic sultams containing two stereocenters. The key point of this strategy relies on the use of vinyl sulfonamides as both, nitrogen nucleophiles and Michael acceptors. The use of phosphazene-derived bases avoided the racemization of the intermediate derivatives, rendering 6-membered ring bicyclic δ-sultams in enantiomerically enriched manner with a small erosion of enantiopurity. Anyway, after recrystallization, final sultams were obtained in almost enantiomerically pure form. Nevertheless, the enantioselective synthesis of either 5-membered ring products or benzofused derivatives was found to be out of the scope of our strategy. (Figure presented.).
- Mulet, Cristina,Escolano, Marcos,Llopis, Sebastián,Sanz, Sergio,Ramírez de Arellano, Carmen,Sánchez-Roselló, María,Fustero, Santos,del Pozo, Carlos
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- Copper-Catalyzed Carbonylative Synthesis of β-Homoprolines from N-Fluoro-sulfonamides
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A new methodology for the carbonylative transformation of N-fluoro-sulfonamides into N-sulfonyl-β-homoproline esters has been described. In the presence of a catalytic amount of Cu(OTf)2, a range of β-homoproline derivatives were prepared in moderate to good yield. The reaction proceeds via the intramolecular cyclization and intermolecular carbonylation of a free carbon radical. Notably, this procedure offers the possibility to build potential functionalized bioactive molecules.
- Wu, Xiao-Feng,Yin, Zhiping,Zhang, Youcan
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supporting information
p. 1889 - 1893
(2020/03/24)
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- A novel chiral yttrium complex with a tridentate linked amido-indenyl ligand for intramolecular hydroamination
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A new chiral silicon-linked tridentate amido-indenyl ligand was developed from indene and enantiopure 1,2-cyclohexanediamine. Its yttrium complex was synthesized, characterized and applied to efficiently catalyze the intramolecular hydroamination of non-a
- Chai, Zhuo,Hua, Dezhi,Li, Kui,Chu, Jiang,Yang, Gaosheng
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supporting information
p. 177 - 179
(2014/01/06)
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- Regioselective copper(II)-mediated bromoamination of unfunctionalized olefins: An efficient route to N-heterocyclic compounds
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Bromoamination of unfunctionalized olefins was realized under mild conditions using copper(II) bromide (CuBr2) as both reaction promoter and bromine source. The reactions could be carried out under open air at ambient temperature, and both N-alkylated and N-tosylated substrates could be converted to the corresponding N-heterocyclic compounds in high regioselectivity and good isolated yields. A variety of biologically important structures could be obtained via subsequent nucleophilic substitution reactions.
- Liu, Gong-Qing,Ding, Zhen-Ying,Zhang, Li,Li, Ting-Ting,Li, Lin,Duan, Lili,Li, Yue-Ming
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supporting information
p. 2303 - 2310
(2014/07/21)
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- A new method for intramolecular chloroamination of unfunctionalized olefins
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A new method for the intramolecular chloroamination of unfunctionalized olefins is reported. The reactions were carried out at room temperature for 3 h using hydrated copper(II) chloride as both promoter and chlorine source, and the corresponding vincinal haloamines were obtained in good isolated yields.
- Liu, Gong-Qing,Li, Wei,Li, Yue-Ming
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supporting information
p. 395 - 402
(2013/05/08)
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- Rhodium(iii)-catalyzed allylic C-H bond amination. Synthesis of cyclic amines from ω-unsaturated N-sulfonylamines
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For the first time, intramolecular allylic amination was conducted using rhodium(iii) according to an "inner-sphere" type mechanism with amines activated by only one electron-withdrawing group. The activation of C(sp 3)-H bonds was chemoselective and allows the access to a variety of substituted cyclic amines such as pyrrolidines and piperidines.
- Cochet, Thomas,Bellosta, Veronique,Roche, Didier,Ortholand, Jean-Yves,Greiner, Alfred,Cossy, Janine
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p. 10745 - 10747
(2013/01/15)
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- Hepatitis C Virus Inhibitors
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Hepatitis C virus inhibitors having the general formula are disclosed. Compositions comprising the compounds and methods for using the compounds to inhibit HCV are also disclosed.
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- Intramolecular hydroamination of aminoalkenes by calcium and magnesium complexes: A synthetic and mechanistic study
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The β-diketiminate-stabilized calcium amide complex [{ArNC(Me)CHC(Me)NAr}Ca{N(SiMe3)2}-(THF)] (Ar = 2,6-diisopropylphenyl) and magnesium methyl complex [{ArNC(Me)CHC(Me)NAr}Mg(Me) (THF)] are reported as efficient precatalysts for hydroamination/cyclization of aminoalkenes. The reactions proceeded under mild conditions, allowing the synthesis of five-, six-, and seven-membered heterocyclic compounds. Qualitative assessment of these reactions revealed that the ease of catalytic turnover increases (i) for smaller ring sizes (5 > 6 > 7), (ii) substrates that benefit from favorable Thorpe-Ingold effects, and (iii) substrates that do not possess additional substitution on the alkene entity. Prochiral substrates may undergo diastereoselective hydroamination/cyclization depending upon the position of the existing stereocenter. Furthermore, a number of minor byproducts of these reactions, arising from competitive alkene isomerization reactions, were identified. A series of stoichiometric reactions between the precatalysts and primary amines provided an important model for catalyst initiation and suggested that these reactions are facile at room temperature, with the reaction of the calcium precatalyst with benzylamine proceeding with ΔG°(298 K) = -2.7 kcal mol-1. Both external amine/amide exchange and coordinated amine/amide exchange were observed in model complexes, and the data suggest that these processes occur via low-activation-energy pathways. As a result of the formation of potentially reactive byproducts such as hexamethyldisilazane, calcium-catalyst initiation is reversible, whereas for the magnesium precatalyst, this process is nonreversible. Further stoichiometric reactions of the two precatalysts with 1-amino-2,2-diphenyl-4-pentene demonstrated that the alkene insertion step proceeds via a highly reactive transient alkylmetal intermediate that readily reacts with N-H σ bonds under catalytically relevant conditions. The results of deuterium-labeling studies are consistent with the formation of a single transient alkyl complex for both the magnesium and calcium precatalysts. Kinetic analysis of the nonreversible magnesium system revealed that the reaction rate depends directly upon catalyst concentration and inversely upon substrate concentration, suggesting that substrate-inhibited alkene insertion is rate-determining.
- Crimmin, Mark R.,Arrowsmith, Merle,Barrett, Anthony G. M.,Casely, Ian J.,Hill, Michael S.,Procopiou, Panayiotis A.
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supporting information; experimental part
p. 9670 - 9685
(2011/03/20)
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- 3,3′-Bis(trisarylsilyl)-substituted binaphtholate rare earth metal catalysts for asymmetric hydroamination
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Chiral 3,3′-bis(trisarylsilyl)-substituted binaphtholate rare earth metal complexes (R)-[Ln{Binol-SiAr3}(o-C6H 4CH2NMe2)(Me2NCH2Ph)] (Ln = Sc, Lu, Y; Binol-SiAr3 = 3,3′-bis(trisarylsilyl)-2,2′- dihydroxy-1,1′-binaphthyl; Ar = Ph (2-Ln), 3,5-xylyl (3-Ln)) and (R)-[La{Binol-Si(3,5-xylyl)3}{E(SiMe3)2}(THF) 2] (E = CH (4a), N (4b)) are accessible via facile arene, alkane, and amine elimination. They are efficient catalysts for the asymmetric hydroamination/cyclization of aminoalkenes, giving TOF of up to 840 h -1 at 25 °C for 2,2-diphenyl-pent-4-enylamine (5c) using (R)-2-Y. Enantioselectivities of up to 95% ee were achieved in the cyclization of 5c with (R)-2-Sc. The reactions show apparently zero-order rate dependence on substrate concentration and first-order rate dependence on catalyst concentration, but rates depend on total amine concentrations. Activation parameters for the cyclization of pent-4-enylamine using (R)-2-Y (ΔH(S)? = 57.4-(0.8) kJ mol-1 and ΔS(S)? = -102(3) J K-1 mol-1; ΔH(R)? = 61.5(0.7) kJ mol-1 and ΔS(R)? = -103(3) J K-1 mol -1) indicate a highly organized transition state. The binaphtholate catalysts were also applied to the kinetic resolution of chiral α-substituted aminoalkenes with resolution factors f of up to 19. The 2,5-disubstituted aminopentenes were formed in 7:1 to ≥50:1 trans diastereoselectivity, depending on the size of the α-substituent of the aminoalkene. Rate studies with (S)-1-phenyl-pent-4-enylamine ((S)-15e) gave the activation parameters for the matching (ΔH? = 52.2(2.8) kJ mol -1, ΔS? = -127(8) J K-1 mol-1 using (S)-2-Y) and mismatching (ΔH? = 57.7(1.3) kJ mol -1, ΔS? = -126(4) J K-1 mol-1 using (R)-2-Y) substrate/catalyst combination. The absolute configuration of the Mosher amide of (2S)-2-methyl-4,4-diphenyl-pyrrolidine and (2R)-methyl-(5S)- phenyl-pyrrolidinium chloride, prepared from (S)-15e, were determined by crystallographic analysis. Catalyst (R)-4a showed activity in the anti-Markovnikov addition of n-propylamine to styrene.
- Gribkov, Denis V.,Hultzsch, Kai C.,Hampel, Frank
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p. 3748 - 3759
(2007/10/03)
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- Enantioselective intramolecular alkene hydroaminations catalyzed by yttrium complexes of axially chiral bis(thiolate) ligands
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(Chemical Equation Presented) A yttrium(III) complex derived from proligand 7c has been shown to be a superior catalyst for enantioselective intramolecular alkene hydroaminations that provide cyclic amines with ee's ranging from 69% to 89%.
- Joon, Young Kim,Livinghouse, Tom
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p. 1737 - 1739
(2007/10/03)
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- Palladium(II)-catalyzed intramolecular diamination of unfunctionalized alkenes
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Intramolecular diamination reactions are described which yield cyclic ureas as direct products of an oxidative alkene transformation in the presence of palladium acetate and iodosobenzene diacetate as terminal oxidant. The reaction is truly catalytic in metal catalyst and represents the proof of principle for this elusive type of alkene oxidation. Copyright
- Streuff, Jan,Hoevelmann, Claas H.,Nieger, Martin,Muniz, Kilian
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p. 14586 - 14587
(2007/10/03)
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- Zirconium catalysed enantioselective hydroamination/cyclisation
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A chiral zirconium alkyl cation catalyses the cyclisation of certain aminoalkenes with enantioselectivity up to 82%, the highest thus far observed for such a process.
- Knight, Paul D.,Munslow, Ian,O'Shaughnessy, Paul N.,Scott, Peter
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p. 894 - 895
(2007/10/03)
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