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
Efficient Cu-Catalyzed Asymmetric Conjugate Additions of Alkylzinc Reagents to Aromatic and Aliphatic Acyclic Nitroalkenes
作者:Dawn M. Mampreian、Amir H. Hoveyda
DOI:10.1021/ol0488338
日期:2004.8.1
Cu-catalyzed method for asymmetric conjugate addition (ACA) of alkylzinc reagents to acyclic disubstituted nitroalkenes is presented. Reactions are typically effected at ambient temperature in the presence of 2 mol % chiral dipeptide phosphine and 1 mol % (CuOTf)(2).C(6)H(6). Nitroalkenes bearing aromatic as well as aliphatic substituents readily undergo asymmetricadditions. [reaction: see text]
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 nitrocompounds were reacted, the stereochemical integrity of the stereocenter was maintained and α-functionalized
A highly efficient, iridium-catalyzed, enantioselectivehydrogenation of β,β-disubstituted nitroalkenes has been developed. Using a complex consisting of iridium and (S,S)-f-spiroPhos as the catalyst, a variety of β,β-disubstituted nitroalkenes were successfully hydrogenated to the corresponding chiral nitroalkanes with excellent enantioselectivities (up to 98% ee) and high turnover numbers (TON=1000)
Light-Enabled Enantiodivergence: Stereospecific Reduction of Activated Alkenes Using a Single Organocatalyst Enantiomer
作者:Theresa Hostmann、John J. Molloy、Kathrin Bussmann、Ryan Gilmour
DOI:10.1021/acs.orglett.9b04263
日期:2019.12.20
Light-enabled enantiodivergence is demonstrated in which the alkene substrate configuration is manipulated (E → Z) prior to organocatalytic reduction with a chiral thiourea and Hantzsch ester. This allows stereodivergent reduction to be regulated at the substrate level with high fidelity and mitigates the need for a second, enantiomeric catalyst (up to 93:07 and 95:5 er). The synthetic utility of this