Dynamic Kinetic Resolution of Secondary Diols via Coupled Ruthenium and Enzyme Catalysis
作者:B. Anders Persson、Fernando F. Huerta、Jan-E. Bäckvall
DOI:10.1021/jo990447u
日期:1999.7.1
Enzymatic acylation of secondary symmetrical diols (as meso/dlmixtures) in combination with ruthenium-catalyzed isomerization of the diol led to efficient dynamic kineticresolution. In this way, a meso/dlmixture of the diol was transformed to enantiomerically pure (R,R)-diacetate, making efficient use of all the diol material. For some of the flexible substrates, substantial amounts of meso-diacetates
starting from commercially available mixtures of the diols (dl/meso approximately 1:1) has been realized by combining a fast ruthenium-catalyzed epimerization with an enzymatic transesterification. The in situ coupling of these two processes produces the diacetates in highyield in >99 % enantiomeric excess.
Stereochemical Studies of the Hydrogenation with an Asymmetrically Modified Raney Nickel Catalyst. The Hydrogenation of Acetylacetone
作者:Akira Tai、Kazuhisa Ito、Tadao Harada
DOI:10.1246/bcsj.54.223
日期:1981.1
The hydrogenation of acetylacetone (I) over asymmetricallymodifiedRaneynickel (MRNi) proceeded, step by step, as follows: acetylacetone (I)\oversetStep 1→ 4-hydroxy-2-pentanone (II) \oversetStep 2→ 2,4-pentanediol (III). It was demonstrated that the optical yield of Step 1 and the diastereomer excess of Step 2 are governed by the ratio of the stereo-differentiating reaction site to the non-stereo-differentiating