Readily available hydrogen bond catalysts for the asymmetric transfer hydrogenation of nitroolefins
作者:Jakob F. Schneider、Markus B. Lauber、Vanessa Muhr、Domenic Kratzer、Jan Paradies
DOI:10.1039/c1ob05059a
日期:——
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
A highlyenantioselectiveFriedel–Craftsalkylation reaction of indoles with acyclic α-substituted β-nitroacrylates is developed under the catalysis of Ni(ClO4)2–bisoxazoline complex at 1 mol % catalyst loading, affording chiral indolic β-nitroesters bearing all-carbon quaternary stereocenters in excellent yields and ees of up to 97%. Transformation of one of the products to β2,2-amino ester and t
A deuterium‐labelingreaction of nitroalkanes in deuterium oxide and the subsequent nitroaldol reaction have been accomplished under basic and organocatalytic conditions to provide the deuterium‐labeled β‐nitroalcohols in high yields and high deuterium contents. β‐Deuterated β‐nitroalcohols could be smoothly obtained from the reaction of nitroalkanes and various electrophiles using the easily‐removal
Metal‐templated organocatalysis: The enantioselective formation of an all‐carbon quaternarystereocenter is catalyzed by the ligand sphere of an inert bis‐cyclometalated iridium complex (see picture). In this complex, the metal‐centered chirality serves as the sole source for the effective asymmetric induction.
Enantioselective addition of nitromethane to α-keto esters catalyzed by copper(<scp>ii</scp>)–iminopyridine complexes
作者:Gonzalo Blay、Victor Hernández-Olmos、José R. Pedro
DOI:10.1039/b716446g
日期:——
The coppercomplex of a chiral iminopyridine easily prepared from (R)-(-)-fenchone and picolylamine catalyzes the enantioselective Henry (nitroaldol) reaction between nitromethane and alpha-keto esters. Good yields and modest to good enantioselectivities are obtained for a wide range of alpha-keto esters, bearing aromatic, alkyl or alkenyl groups attached to the ketone carbonyl group.