CATALYST COMPOSITIONS AND THEIR USE IN THE DE-ENRICHMENT OF ENANTIOMERICALLY ENRICHED SUBSTRATES
申请人:Blacker Andrew John
公开号:US20090163719A1
公开(公告)日:2009-06-25
There is provided a process for the de-enrichment of enantiomerically enriched compositions which comprises reacting an enantiomerically enriched composition comprising at least a first enantiomer or diastereomer of a substrate comprising a carbon-heteroatom bond, wherein the carbon is a chiral centre and the heteroatom is a group V heteroatom, in the presence of a catalyst system and optionally a reaction promoter to give a product composition comprising first and second enantiomers or diastereomers of the substrate having a carbon-heteroatom bond, the ratio of second to first enantiomer or diastereomer in the product composition being greater than the ratio of second to first enantiomer or diastereomer in the enantiomerically enriched composition. Preferred catalyst systems include transition metal halide complex of the formula M
n
X
p
Y
r
wherein M is a transition metal; X is a halide; Y is a neutral optionally substituted hydrocarbyl complexing group, a neutral optionally substituted perhalogenated hydrocarbyl complexing group, or an optionally substituted cyclopentadienyl complexing group; and n, p and r are integers. The reaction promoter is preferably a halide salt.
Diastereoselective desymmetrization of diarylphosphinous acid-borane amides under Birch reduction
作者:Marek Stankevič
DOI:10.1039/c4ob02440k
日期:——
Treatment of diarylphosphinous acid-borane amides possessing chiral amido functionality with an alkali metal solution in liquid ammonia induced a preferential dearomatization of one aryl substituent at phosphorus leading to the formation of non-equimolar amounts of diastereomers. Diastereoselectivity of dearomatization depends strongly on the structure of a chiral auxiliary.
Catalytic Racemisation of Chiral Amines and Application in Dynamic Kinetic Resolution
作者:A. John Blacker、Matthew J. Stirling、Michael I. Page
DOI:10.1021/op060233w
日期:2007.5.1
back to the amine. When an optically active amine is mixed with the iridium precatalyst, racemisation is observed. The SCRAM catalyst is used under mild conditions compatible with suitable enzymes and acyldonors, and thus the DKR of an amine has been effected, giving significantly higher yield than if the enzyme alone was used. A mixed carbonate was identified as the optimal acyldonor, giving a carbamate