Enantioseparation of allenes by liquid chromatography
摘要:
The enantioseparation of allenes bearing ester, thioester, keto, and hydroxy groups by liquid chromatography using cellulose triacetate as chiral stationary phase was examined. On the preparative scale, enrichments up to > 98% ee were achieved.
In this account, recent accomplishments in the field of target-oriented synthesis involving allenes are summarized. Allenic α-amino acid derivatives 9, which are of interest as possible vitamin B 6 decarboxylase inhibitors, were prepared by 1,6-addition of the cyano-Gilman reagent t-Bu 2 CuLi-LiCN to 2-amino-substituted enynoates 8. and selective deprotection at either the amino or the ester group
Efficient Synthesis of 2-Hydroxy-3,4-dienoates by Oxidation of Zirconiumallenyl Enolates with Dimethyldioxirane
作者:Norbert Krause、Anja Hoffmann-Röder
DOI:10.1055/s-2006-942409
日期:2006.7
The α-hydroxylation of zirconiumallenyl enolates, obtained from β-allenic esters by deprotonation with LDA or LiN(SiMe3)2 and transmetalation with Cp2ZrCl2, with dimethyldioxirane (DMDO) selectively affords 2-hydroxy-3,4-dienoates. The oxidation proceeds usually with high yield and substrate conversion and tolerates even sensitive or unreactive substrates.
Ruthenium-Catalyzed Flash Oxidation of Allenes to α,α'-Dihydroxyketones
作者:Michael Laux、Norbert Krause
DOI:10.1055/s-1997-5759
日期:1997.7
The ruthenium-catalyzed flash oxidation of β-allenic esters 1 furnishes α,α'-dihydroxyketones 2 in 24-72% yield. In the case of the chiral allene 1e, the oxidation proceeds with good diastereoselectivity (88% de), i.e. with efficient axis to center chirality transfer. The flash oxidation can also be used for the synthesis of corticosteroids, as exemplified by the transformation of allenic steroid 4 into dihydroxyketone 5.
1,6-Addition of organolithium compounds to acceptor-substituted enynes catalyzed by a copper(I) arenethiolate
作者:Andreas Haubrich、Mayra van Klaveren、Gerard van Koten、Gabriele Handke、Norbert Krause
DOI:10.1021/jo00073a055
日期:1993.10
Enantioseparation of allenes by liquid chromatography
作者:Norbert Krause、Gabriele Handke
DOI:10.1016/0040-4039(91)80482-l
日期:1991.12
The enantioseparation of allenes bearing ester, thioester, keto, and hydroxy groups by liquid chromatography using cellulose triacetate as chiral stationary phase was examined. On the preparative scale, enrichments up to > 98% ee were achieved.