Large- scale ruthenium- and enzyme- catalyzed dynamic kinetic resolution of (rac)-1-phenylethanol

• Krisztián Bogár,
• Belén Martín-Matute and
• Jan-E. Bäckvall

Beilstein J. Org. Chem. 2007, 3, No. 50, doi:10.1186/1860-5397-3-50

• larger scale and the results are summarized in Table 1. On a 10 mmol-scale, 1 mol% of Ru-catalyst 1 can be used to achieve 90% yield of acetate 3 (99% ee) after 18 h at room temperature (entry 1). A decrease of the catalyst loading to 0.5 mol% afforded 87% of enantiopure acetate, although a longer

• high efficiency of the latter reaction suggests that the racemization catalyst loading can be further decreased, and that an increased reaction temperature may facilitate this decrease. Indeed, a DKR reaction at 70°C on a 1 mol-scale employing only 0.05 mol% Ru-catalyst in a more concentrated reaction

• . Under optimized reaction conditions, DKR of 1-phenylethanol (2) was performed delivering 159 g (97% yield) of enantiomerically pure (R)-1-phenylethanol acetate (3) in a short reaction time (20 h) using 0.05 mol% of Ru-catalyst 1, and small amounts of enzyme. The employed heterogeneous biocatalyst