58717-85-4Relevant academic research and scientific papers
Low-Pressure Cobalt-Catalyzed Enantioselective Hydrovinylation of Vinylarenes
Movahhed, Sohajl,Westphal, Julia,Dindaro?lu, Mehmet,Falk, Anna,Schmalz, Hans-Günther
supporting information, p. 7381 - 7384 (2016/05/24)
An efficient and practical protocol for the enantioselective cobalt-catalyzed hydrovinylation of vinylarenes with ethylene at low (1.2 bar) pressure has been developed. As precatalysts, stable [L2CoCl2] complexes are employed that are activated in situ with Et2AlCl. A modular chiral TADDOL-derived phosphine-phosphite ligand was identified that allows the conversion of a broad spectrum of substrates, including heterocyclic vinylarenes and vinylferrocene, to smoothly afford the branched products with up to 99 % ee and virtually complete regioselectivity. Even polar functional groups, such as OH, NH2, CN, and CO2R, are tolerated.
Neutral and Cationic Palladium Complexes of P-Stereogenic Phosphanes Bearing a Heterocyclic Substituent
Clavero, Pau,Grabulosa, Arnald,Rocamora, Mercè,Muller, Guillermo,Font-Bardia, Mercè
, p. 4216 - 4225 (2016/09/16)
The coordination chemistry of 13 optically pure P-stereogenic diarylmonophosphanes P(Het)PhR [Het = 4-dibenzofuranyl (DBF), 4-dibenzothiophenyl (DBT), 4-dibenzothiophenyl S,S-dioxide (DBTO2) and 1-thianthrenyl (TA); R = OMe, Me, iPr, Fc (ferroc
Improvements and Applications of the Transition Metal-Free Asymmetric Allylic Alkylation using Grignard Reagents and Magnesium Alanates
Grassi, David,Alexakis, Alexandre
supporting information, p. 3171 - 3186 (2015/11/03)
Two new N-heterocyclic carbene (NHC) ligands have been synthesized and employed in the transition metal-free asymmetric allylic alkylation (AAA) mediated by Grignard reagents and magnesium alanates. The employment of these ligands showed high yields and improved regio- and enantioselectivity in the formation of tertiary and quaternary stereocenters. Moreover, the low catalyst loading (up to 0.3 mol%) and high scalability (up to 10 mmol) of this improved methodology provide a convenient access to biologically active compounds and synthetically valuable intermediates.
Synthesis of P-Stereogenic Phosphoramidite and Phosphorodiamidite Ligands and Their Application in Asymmetric Catalysis
Schmitz, Christian,Leitner, Walter,Franciò, Giancarlo
, p. 6205 - 6230 (2015/10/06)
A series of P-stereogenic monodentate phosphoramidite (PNO2) and phosphorodiamidite (PN2O) ligands based on chiral Betti bases has been prepared by modular synthetic procedures. The chirality at the phosphorus can be controlled to a large extent by the synthetic route, leading to stereoselective access to single P-epimers. The absolute configuration of the P-atom was assigned by X-ray diffraction analysis. The new ligands were evaluated in asymmetric catalysis and the influence of the exocyclic amine or alcohol moiety as well as the interplay between the P-chirality and the stereocenters in the backbone were investigated. Enantioselectivities of up to 85 and 83 % ee were obtained in the Rh-catalyzed hydrogenation of dimethyl itaconate and in the Pd-catalyzed allylic amination of (rac)-(E)-1,3-diphenylallyl acetate with benzylamine, respectively. In the Ni-catalyzed hydrovinylation of styrene, ee values of up to 68 %, excellent chemoselectivities, and high activities (TOFav up to 3000 h-1) were achieved. A series of phosphoramidite (R = OR) and phosphorodiamidite (R = NR2) ligands containing a stereogenic phosphorus atom has been synthesized from chiral Betti bases as amino alcohol building blocks. The new ligands have been applied in three different asymmetric metal-catalyzed reactions, and the interplay between P-stereochemistry, structural features of R, and chirality at the backbone evaluated.
P-Stereogenic monophosphines with the 2-p-terphenylyl and 1-pyrenyl substituents. Application to Pd and Ru asymmetric catalysis
Clavero, Pau,Grabulosa, Arnald,Font-Bardia, Mercè,Muller, Guillermo
, p. 183 - 190 (2014/06/10)
The synthesis of five optically pure P-stereogenic monophosphines of the type PPhArR (Ar = 2-p-terphenylyl (a), 1-pyrenyl (b); R = OMe, Me, i-Pr) is described. The ligands were fully characterised and the absolute configurations of PPh(1-pyrenyl)R (3b and 5b; R = OMe and Me respectively) were confirmed by X-ray diffraction. The complexation of the monophosphines to Pd and Ru organometallic units yielded the neutral complexes [PdCl(η3-2-Me- allyl)P] (10-12) and [RuCl2(η6-p-cymene)P] (16-18). Complete characterisation, including the crystal structure determination of [RuCl2(η6-p-cymene)(PMePh(2-p-terphenyl))] (17a) is provided. Neutral palladium complexes appeared as mixtures of two diastereomers in solution according to NMR. The synthesis and characterisation of four cationic [Pd(η3-2-Me-allyl)(P)2]PF6 (13 and 14) is also described. The application of neutral Pd complexes to catalytic styrene hydrovinylation afforded moderate conversions, high chemoselectivities (>92%) to 3-phenyl-1-butene and up to 43% ee with precursor 12a. Cationic Pd complexes were tested as catalytic precursors in allylic substitution of rac-3-acetoxy-1,3-diphenyl-1-propene (rac-I), with the anion of dimethylmalonate and benzylamine as nucleophiles, obtaining full conversions and up to 80% ee in alkylation and 60% ee in amination with precursor 13a. Finally, ruthenium complexes were used as catalytic precursors in transfer hydrogenation of acetophenone, with complete conversions after several hours but low enantioselectivities.
Asymmetric hydrovinylation and hydrogenation with metal complexes of C 3-symmetric tris-binaphthyl monophosphites
Carrilho, Rui M. B.,Costa, Gon?alo N.,Neves, ?ngela C. B.,Pereira, Mariette M.,Grabulosa, Arnald,Bay?n, J. Carles,Rocamora, Mercè,Muller, Guillermo
, p. 1034 - 1041 (2014/03/21)
Neutral allyl-palladium complexes stabilised by bulky tris-binaphthyl monophosphite ligands have been prepared and fully characterised in solution by NMR spectroscopy, which evidenced a dynamic equilibrium between two diastereomeric species. The new allyl
Asymmetric hydrovinylation and hydrogenation with metal complexes of C3-symmetric tris-binaphthyl monophosphites
Carrilho, Rui M. B.,Costa, Gon?alo N.,Neves, ?ngela C. B.,Pereira, Mariette M.,Grabulosa, Arnald,Bay?n, J. Carles,Rocamora, Mercè,Muller, Guillermo
, p. 1034 - 1041 (2015/04/27)
Neutral allyl-palladium complexes stabilised by bulky tris-binaphthyl monophosphite ligands have been prepared and fully characterised in solution by NMR spectroscopy, which evidenced a dynamic equilibrium between two diastereomeric species. The new allyl
Asymmetric construction of quaternary stereogenic centers via auxiliary-based SN2′ reactions: A case of 1,7-relative stereogenesis
Denmark, Scott E.,Marble, Lyndon K.
, p. 559 - 590 (2016/11/15)
The stereoselective construction of quaternary stereogenic centers is described that employs an allylic substitution through the intermediacy of a chiral carbamate leaving group. Five carbamates with two substituents at the allylic terminus combined with
Copper-free asymmetric allylic alkylation with a grignard reagent: Design of the ligand and mechanistic studies
Grassi, David,Dolka, Chrysanthi,Jackowski, Olivier,Alexakis, Alexandre
supporting information, p. 1466 - 1475 (2013/02/25)
The Cu-free asymmetric allylic alkylation, catalysed by NHC, with Grignard reagents is reported on allyl bromide derivatives with good results. The enantioselectivity was quite homogeneous (around 85 % ee) on large and various substrates, regardless of the nature of the Grignard reagent. The formation of stereogenic quaternary centres was highly regioselective for both aliphatic and aromatic derivatives with good enantiomeric excess (up to 92 % ee). The methodology developed was found to be complementary with the Cu-catalysed version. Several new NHCs were tested with improved efficiency. In addition, mechanistic studies, using NMR spectroscopy, led to the discovery of the catalytically active species. Copyright
NOBIN-based phosphoramidite and phosphorodiamidite ligands and their use in asymmetric nickel-catalysed hydrovinylation
Schmitkamp, Mike,Leitner, Walter,Francio, Giancarlo
, p. 589 - 594 (2013/05/08)
Phosphoramidite and P-stereogenic phosphorodiamidite ligands derived from (Sa)-2-phenylamino-2′-hydroxy-1,1′-binaphthyl (N-Ph-NOBIN) and bis(1-phenyl-ethyl)amine were synthesised, fully characterised, and the absolute configuration of the stereogenic phosphorus atoms was assigned. The phosphoramidite ligand L2 features three non-bridged substituents at phosphorus comprising the bis(1-phenylethyl)amine and two NOBIN moieties. The NOBIN units are bound to the phosphorus through the oxygen atoms with two pendant nitrogen atoms. In the Ni-catalysed hydrovinylation of styrene no conversion was observed with the phosphorodiamidites, while the phosphoramidite ligands led to active catalysts with a marked co-operative effect on selectivities. Whereas the racemic product was obtained with the (S a,Sa,SC,SC) diastereomer, the (Sa,Sa,RC,RC) diastereomer proved to be one of the best ligands for this reaction, leading to almost perfect selectivity and ees of up to 91%.
