Alkenes as Ketol Surrogates-A New Approach toward Enantiopure Acyloins
Bernd Plietker*
*Institut für Organische Chemie, Universität Stuttgart,
Pfaffenwaldring 55, 70569 Stuttgart, Germany, Email: bernd.plietker
oc.uni-stuttgart.de
B. Plietker, Org. Lett., 2004, 6, 289-291.
DOI: 10.1021/ol0362663
Abstract
A two-step sequence of asymmetric dihydroxylation and regioselective monooxidation gave enantiopure α-hydroxy ketones (acyloins). The combination of RuCl3/Oxone/NaHCO3 was used in the first catalytic regioselective oxidation of vic-diols to α-ketols.
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Details
This paper by Bernd Plietker introduces a novel method for synthesizing enantiopure α-hydroxy ketones (acyloins) using alkenes as ketol surrogates. The approach involves a two-step process: asymmetric dihydroxylation followed by regioselective monooxidation. The key innovation is the use of cyclic ruthenates and a combination of RuCl3, Oxone, and NaHCO3, which allows for the selective oxidation of vic-diols to α-ketols. This method provides high regioselectivity and maintains enantiomeric excess without the need for inert gas or dry solvents. The study demonstrates that Oxone is the most effective reoxidant for this process, yielding high conversion rates and selectivity. The method tolerates a broad range of functional groups and is particularly effective for electron-poor substrates. The findings also support the proposed mechanism involving cyclic ruthenates and highlight the potential for future asymmetric developments. This new protocol complements existing α-hydroxylation methods and offers a convenient route to enantiopure acyloins, which are valuable building blocks in organic synthesis. The research was supported by various scientific funding bodies and detailed experimental procedures are available online.
Key Words
dihydroxylation, α-hydroxy ketones, ruthenium, oxone
ID: J54-Y2004-070
