4453-82-1Relevant articles and documents
Kinetic resolution of racemic allylic alcoholsviairidium-catalyzed asymmetric hydrogenation: scope, synthetic applications and insight into the origin of selectivity
Wu, Haibo,Margarita, Cristiana,Jongcharoenkamol, Jira,Nolan, Mark D.,Singh, Thishana,Andersson, Pher G.
, p. 1937 - 1943 (2021/02/22)
Asymmetric hydrogenation is one of the most commonly used tools in organic synthesis, whereas, kinetic resolutionviaasymmetric hydrogenation is less developed. Herein, we describe the first iridium catalyzed kinetic resolution of a wide range of trisubstituted secondary and tertiary allylic alcohols. Large selectivity factors were observed in most cases (sup to 211), providing the unreacted starting materials in good yield with high levels of enantiopurity (ee up to >99%). The utility of this method is highlighted in the enantioselective formal synthesis of some bioactive natural products including pumiliotoxin A, inthomycin A and B. DFT studies and a selectivity model concerning the origin of selectivity are presented.
Half-Sandwich Nickel(II) NHC-Picolyl Complexes as Catalysts for the Hydrosilylation of Carbonyl Compounds: Evidence for NHC-Nickel Nanoparticles under Harsh Reaction Conditions
Ulm, Franck,Shahane, Saurabh,Truong-Phuoc, Lai,Romero, Thierry,Papaefthimiou, Vasiliki,Chessé, Matthieu,Chetcuti, Michael J.,Pham-Huu, Cuong,Michon, Christophe,Ritleng, Vincent
supporting information, p. 3074 - 3082 (2021/08/03)
The cationic [NiCp(Mes-NHC-CH2py]Br complex 2 a was prepared directly by the reaction of nickelocene with 1-(2-picolyl)-3-mesityl-imidazolium bromide (1), and its PF6? derivative 2 b, by subsequent salt metathesis. X-ray diffraction studies and Variable Temperature 1H NMR experiments run with 2 a and 2 b strongly suggest the bidentate coordination of the picolyl-functionalized carbene to the nickel both in the solid state and in solution in both cases. These data suggest the absence of hemilabile behavior of the latter, even in the presence of a coordinating anion. Both complexes show similar activity in aldehyde hydrosilylation, further implying the absence of hemilability of the picolyl-functionalized carbene, and effectively reduce a broad scope of aldehydes in the absence of additive under mild conditions. In the case of ketones, effective hydrosilylation is only observed in the presence of a catalytic amount of potassium t-butoxide at 100 °C. Dynamic light scattering, scanning transmission electron microscopy and X-ray photoelectron spectroscopy show evidence for the involvement of NHC-picolyl-Ni nanoparticles under these conditions.
Selective Hydrogenation and Hydrodeoxygenation of Aromatic Ketones to Cyclohexane Derivatives Using a Rh&at;SILP Catalyst
Bordet, Alexis,Emondts, Meike,Leitner, Walter,Moos, Gilles
supporting information, p. 11977 - 11983 (2020/06/02)
Rhodium nanoparticles immobilized on an acid-free triphenylphosphonium-based supported ionic liquid phase (Rh&at;SILP(Ph3-P-NTf2)) enabled the selective hydrogenation and hydrodeoxygenation of aromatic ketones. The flexible molecular approach used to assemble the individual catalyst components (SiO2, ionic liquid, nanoparticles) led to outstanding catalytic properties. In particular, intimate contact between the nanoparticles and the phosphonium ionic liquid is required for the deoxygenation reactivity. The Rh&at;SILP(Ph3-P-NTf2) catalyst was active for the hydrodeoxygenation of benzylic ketones under mild conditions, and the product distribution for non-benzylic ketones was controlled with high selectivity between the hydrogenated (alcohol) and hydrodeoxygenated (alkane) products by adjusting the reaction temperature. The versatile Rh&at;SILP(Ph3-P-NTf2) catalyst opens the way to the production of a wide range of high-value cyclohexane derivatives by the hydrogenation and/or hydrodeoxygenation of Friedel–Crafts acylation products and lignin-derived aromatic ketones.