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|Type:||Artigo de evento|
|Title:||Preparation Of An (-)-ephedrine Intermediate Through Asymmetric Reduction Of 1-phenyl-1,2-propanedione By Anaerobically Pre-treated Baker's Yeast|
|Abstract:||The influence of using an anaerobically pre-treated baker's yeast on the reduction of (R)-1-hydroxy-1-phenyl-2-propanone (2) and (S)-2-hydroxy-1-phenyl- 1-propanone (4) was investigated in comparison with non-pre-treated baker's yeast reduction (control experiments). We observed that there is no significant difference between the anaerobically pre-treated yeast and the control experiment on the reduction rates of 2. On the other hand, the rate of reduction of 4 mediated by the anaerobically pre-treated yeast is much slower than the aerobic experiment. To improve the regioselectivity of reduction of 1-phenyl-1,2-propanedione (1), a baker's yeast suspension was pre-treated with nitrogen (60 min) followed by oxygen (20 min), to give 2 in 28-31% of yields (96% e.e.) and 3 in 42-62% (>99% e.e.) after 75-90 min of reaction. © 2004 Elsevier B.V. All rights reserved.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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