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.
通过使用适当的保护基团,可以高产率和高对映选择性地实现δ位含有杂原子的酮的不对称转移氢化。
Enantiospecific synthesis of (+)-(R)-6,7-dimethoxy-2-methyl-4-phenyl-1,2,3,4-tetrahydroisoquinoline from (+)-(S)-2-methylamino-1-phenylethanol (halostachine)
作者:Steven J. Coote、Stephen G. Davies、David Middlemiss、Alan Naylor
DOI:10.1039/p19890002223
日期:——
Acid-promoted cyclisation of (+)-(R)-N-(3,4-dimethoxybenzyl)halostachine tricarbonylchromium at –20 °C is highly stereoselective, proceeding with retention of configuration, to yield, after removal of the tricarbonylchromium unit, homochiral (+)-(R)-6,7-dimethoxy-2-methyl-4-phenyl-1,2,3,4tetrahydroisoquinoline. In contrast, cyclisation of (–)-(R)-N-(3,4-dimethoxybenzyl)halostachine under acidic conditions