7796-78-3Relevant academic research and scientific papers
Copper(I) thiolate catalysts in asymmetric conjugate addition reactions
Arink, Anne M.,Braam, Thijs W.,Keeris, Roy,Jastrzebski, Johann T. B. H.,Benhaim, Cyril,Rosset, Stephane,Alexakis, Alexandre,Van Koten, Gerard
, p. 1959 - 1962 (2004)
Equation presented. Full conversion and enantioselectivities up to 83% have been obtained in the conjugate addition reactions of diethyl zinc to Michael acceptors catalyzed by well-defined (chiral) copper(I) aminoarenethiolates. Interesting differences between organozinc or Grignard reagents have been found: for cyclic enones R2Zn reagents afford better results, whereas earlier work showed that RMgX reagents react more selectively with acyclic enones.
Metal-Free Deoxygenation of Chiral Nitroalkanes: An Easy Entry to α-Substituted Enantiomerically Enriched Nitriles
Pirola, Margherita,Faverio, Chiara,Orlandi, Manuel,Benaglia, Maurizio
supporting information, p. 10247 - 10250 (2021/06/18)
A metal-free, mild and chemodivergent transformation involving nitroalkanes has been developed. Under optimized reaction conditions, in the presence of trichlorosilane and a tertiary amine, aliphatic nitroalkanes were selectively converted into amines or nitriles. Furthermore, when chiral β-substituted nitro compounds were reacted, the stereochemical integrity of the stereocenter was maintained and α-functionalized nitriles were obtained with no loss of enantiomeric excess. The methodology was successfully applied to the synthesis of chiral β-cyano esters, α-aryl alkylnitriles, and TBS-protected cyanohydrins, including direct precursors of four active pharmaceutical ingredients (ibuprofen, tembamide, aegeline and denopamine).
Boosting Conjugate Addition to Nitroolefins Using Lithium Tetraorganozincates: Synthetic Strategies and Structural Insights
Dell'Aera, Marzia,Perna, Filippo Maria,Vitale, Paola,Altomare, Angela,Palmieri, Alessandro,Maddock, Lewis C. H.,Bole, Leonie J.,Kennedy, Alan R.,Hevia, Eva,Capriati, Vito
supporting information, p. 8742 - 8748 (2020/07/04)
We report the first transition metal catalyst- and ligand-free conjugate addition of lithium tetraorganozincates (R4ZnLi2) to nitroolefins. Displaying enhanced nucleophilicity combined with unique chemoselectivity and functional group tolerance, homoleptic aliphatic and aromatic R4ZnLi2 provide access to valuable nitroalkanes in up to 98 % yield under mild conditions (0 °C) and short reaction time (30 min). This is particularly remarkable when employing β-nitroacrylates and β-nitroenones, where despite the presence of other electrophilic groups, selective 1,4 addition to the C=C is preferred. Structural and spectroscopic studies confirmed the formation of tetraorganozincate species in solution, the nature of which has been a long debated issue, and allowed to unveil the key role played by donor additives on the aggregation and structure of these reagents. Thus, while chelating N,N,N’,N’-tetramethylethylenediamine (TMEDA) and (R,R)-N,N,N’,N’-tetramethyl-1,2-diaminocyclohexane (TMCDA) favour the formation of contacted-ion pair zincates, macrocyclic Lewis donor 12-crown-4 triggers an immediate disproportionation process of Et4ZnLi2 into equimolar amounts of solvent-separated Et3ZnLi and EtLi.
Deoxycholic acid-derived biaryl phosphites as versatile and enantioselective ligands in the rhodium-catalyzed conjugate addition of arylboronic acids to nitroalkenes
Jumde, Varsha R.,Iuliano, Anna
supporting information, p. 3475 - 3483 (2013/12/04)
A highly enantioselective conjugate addition of arylboronic acids to cyclic as well as acyclic aromatic and aliphatic nitroalkenes is presented. The rhodium complexes obtained from deoxycholic acid-derived binaphthyl and flexible biphenyl phosphites showed good activity as well as very high enantioselectivity (ee up to 99%) in the conjugated addition even in the presence of challenging substrates such as 1-nitrocyclohexene or aliphatic acyclic nitroalkenes. Copyright
Highly enantioselective hydrogenation of β,β-disubstituted nitroalkenes
Li, Shengkun,Huang, Kexuan,Cao, Bonan,Zhang, Jiwen,Wu, Wenjun,Zhang, Xumu
supporting information; experimental part, p. 8573 - 8576 (2012/09/10)
Building the building blocks: A highly enantioselective hydrogenation of ?-aryl-?-alkyl disubstituted nitroalkenes 1 has been developed. This method results in enantiomerically pure nitroalkanes 2, which are versatile precursors for chemical synthesis.
Readily available hydrogen bond catalysts for the asymmetric transfer hydrogenation of nitroolefins
Schneider, Jakob F.,Lauber, Markus B.,Muhr, Vanessa,Kratzer, Domenic,Paradies, Jan
supporting information; experimental part, p. 4323 - 4327 (2011/07/08)
This paper focuses on readily accessible thiourea hydrogen bond catalysts derived from amino acids, whose steric and electronic features are modulated by their degree of substitution at the carbinol carbon center. These catalysts were applied in the asymmetric transfer hydrogenation of nitroolefins furnishing the chiral products in up to 99% yield and 86% enantiomeric excess. The proposed catalyst's mode of action is supported by mechanistic investigations.
Reductive biotransformation of nitroalkenes via nitroso-intermediates to oxazetes catalyzed by xenobiotic reductase A (XenA)
Durchschein, Katharina,Fabian, Walter M. F.,MacHeroux, Peter,Zangger, Klaus,Trimmel, Gregor,Faber, Kurt
experimental part, p. 3364 - 3369 (2011/06/25)
A novel reductive biotransformation pathway for β,β-disubstituted nitroalkenes catalyzed by flavoproteins from the Old Yellow Enzyme (OYE) family was elucidated. It was shown to proceed via enzymatic reduction of the nitro-moiety to furnish the corresponding nitroso-alkene, which underwent spontaneous (non-enzymatic) electrocyclization to form highly strained 1,2-oxazete derivatives. At elevated temperatures the latter lost HCN via a retro-[2 + 2]-cycloaddition to form the corresponding ketones. This pathway was particularly dominant using xenobiotic reductase A, while pentaerythritol tetranitrate-reductase predominantly catalyzed the biodegradation via the Nef-pathway.
Sugar-based phosphite and phosphoroamidite ligands for the Cu-catalyzed asymmetric 1,4-addition to enones
Raluy, Eva,Pamies, Oscar,Dieguez, Montserrat,Rosset, Stephane,Alexakis, Alexander
experimental part, p. 2167 - 2172 (2010/03/24)
A modular sugar-based phosphoroamidite L1-L5a-g and phosphite L6-L9a-g ligand library was tested in the asymmetric Cu-catalyzed 1,4-conjugate addition reactions of β-substituted (cyclic and linear) and β,β′-disubstituted (cyclic) enones. The selectivity d
Organocatalytic asymmetric transfer hydrogenation of nitroolefins
Martin, Nolwenn J. A.,Ozores, Lidia,List, Benjamin
, p. 8976 - 8977 (2008/02/10)
We describe a highly efficient and highly enantioselective Hantzsch ester mediated conjugate transfer hydrogenation of β,β-disubstituted nitroolefins that is catalyzed by a Jacobsen-type thiourea catalyst. Copyright
Application of the chiral bis(phosphine) monoxide ligand to catalytic enantioselective addition of dialkylzinc reagents to β-nitroalkenes
Cote, Alexandre,Lindsay, Vincent N. G.,Charette, Andre B.
, p. 85 - 87 (2007/10/03)
(Chemical Equation Presented) Me-DuPHOS monoxide is shown to be a very effective ligand in the enantioselective copper-catalyzed addition of dialkylzinc reagents to β-nitroalkenes providing access to chiral nitroalkanes. The major advantages of this process are high yields, broad and complementary substrate scope, and high enantioselectivities. The effect of achiral dummy ligands as an additive has also been documented.
