Optimization of and Mechanistic Considerations for the Enantioselective Dihydroxylation of Styrene Catalyzed by Osmate-Laccase-Poly(2-Methyloxazoline) in Organic Solvents

摘要

The Sharpless dihydroxylation of styrene with the artificial metalloenzyme osmate-laccase-poly(2-methyloxazoline) was investigated to find reaction conditions that allow this unique catalyst to reveal its full potential. After changing the co-oxidizing agent to tert-butyl hydroperoxide and optimizing the osmate/enzyme ratio, the turnover frequency and the turnover number could be increased by an order of magnitude, showing that the catalyst can compete with classical organometallic catalysts. Varying the metal in the active center showed that osmate is by far the most active catalytic center, but the reaction can also be realized with permanganate and iron(II) salts.