acyclic diols, in particular 1,2-diols, were selectively monobenzoylated in good yields by the reaction with benzoyl chloride in the presence of a catalytic amount of dimethyltin dichloride and inorganic bases such as potassium carbonate. Furthermore, the method was successfully applied to a kinetic resolution of racemic 1-phenyl-1,2-ethanediol using a chiral organotin catalyst. The ee was dependent
ASYMMETRIC REDUCTION OF PROCHIRAL HYDROXY KETONES WITH A CHIRAL REDUCING AGENT PREPARED FROM TIN(II) CHLORIDE, A CHIRAL DIAMINE, AND DIISOBUTYLALUMINUM HYDRIDE
Asymmetric reduction of prochiral α- and β-hydroxy ketones with a reagent, generated from tin(II) chloride, a chiral diamine, and diisobutylaluminum hydride, afforded the corresponding dihydroxy compounds in good chemical and optical yields. Optical yields depended on the nature of the protective groups of hydroxyl function.
Efficient P-Chiral Biaryl Bisphosphorus Ligands for Palladium-Catalyzed Asymmetric Hydrogenation
作者:Wenhao Jiang、Qing Zhao、Wenjun Tang
DOI:10.1002/cjoc.201700645
日期:2018.2
A series of structurally novel P‐chiral biaryl bisphosphorus ligands L1‐L5 (BABIBOPs) are developed, providing high efficiency for the first time in palladium‐catalyzedasymmetrichydrogenation of β‐aryl and β‐alkyl substituted β‐keto esters. With the Pd‐L3 (iPr‐BABIBOP) catalyst, a series of chiral β‐hydroxyl carboxylic esters are formed in excellent enantioselectivities (up to>99% ee) and yields
The use of an enantiomerically pure amino alcohol, coupled to a transfer hydrogenation process, in the asymmetric catalysis of the reduction of ketones to alcohols, is described. The process works well for unfunctionalised ketones, affording e.e.s of up to 98%, and excellent conversions. We have recently extended, for the first time in this application, the scope of the methodology to the reductions of a-heteroatom substituted substrates, through the use of the appropriate protecting groups on each atom.
Asymmetric Transfer Hydrogenation of α-Amino and α-Alkoxy Substituted Ketones
作者:Jennifer A. Kenny、Matthew J. Palmer、Athene R. C. Smith、Tim Walsgrove、Martin Wills
DOI:10.1055/s-1999-2906
日期:——
Through the use of appropriate protecting groups, the asymmetric transfer hydrogenation of ketones bearing heteroatoms at the α-position may be achieved in high yield and enantioselectivity.