| 摘要 |
A process for the preparation of (R)-1-(2,3-difluoro-6-nitrophenoxy)-propan-2-ol, which is a useful intermediate in the synthesis of the widely used antibiotic Levofloxacin is provided. A process for the preparation of (R)-1-(2,3-difluoro-6-nitrophenoxy)-2-trimethylsiloxypropane is also described. The process includes the ring opening of (R)-propylene oxide with 2,3-difluoro-6-nitrophenyl trimethylsilyl ether in the presence of an optically active Co(salen) catalyst. The trimethylsilyl group of the reactant is transferred to the product aryloxy alcohol, which serves to protect the secondary alcohol in situ. Upon isolation, the trimethylsilyl group is removed and the resulting regioisomeric mixture purified to yield the desired (R)-1-(2,3-difluoro-6-nitrophenoxy)-propan-2-ol in high purity and yield.
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