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DOI: 10.1055/s-0041-1737856
Bäckvall’s Dynamic Kinetic Resolution
Key words
acylation - dynamic kinetic resolution (DKR) - enzyme catalysis - racemization - ruthenium catalysis![](https://www.thieme-connect.de/media/synfacts/202203/i_m006_s1_10-1055_s-0041-1737856.gif)
Significance
In 1997, Bäckvall and co-workers presented a ruthenium(II)-catalyzed racemization of secondary alcohols coupled with enzymatic kinetic resolution to form the corresponding acetates in high yields and enantiomeric excesses. This protocol’s advantage over common kinetic resolution is a theoretical yield of the enantiomerically enriched acetates of 100%. A monomeric ruthenium complex later introduced is able to racemize alcohols in under 10 min at room temperature with a low catalyst loading of 0.5 mol% (Angew. Chem. Int. Ed. 2004, 43, 6535). This catalyst is still the benchmark for the racemization of secondary alcohols.
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Comment
Bäckvall’s dynamic kinetic resolution (DKR) is the first example of a dual catalytic system combining transition-metal and enzyme catalysis. From a mechanistic point of view, a slippage of the Cp ring from η5- to η3-coordination to form a free coordination site was initially assumed in the racemization process, but computations as well as mechanistic experiments strongly suggest a CO dissociation mechanism (Acc. Chem. Res. 2013, 46, 2545).
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Publication History
Article published online:
16 February 2022
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