Novel preparation method for sitafloxacin intermediate

The invention provides a novel preparation method for sitafloxacin intermediate (7S)-amino-5-[1(R)-5-phenethyl] 4-oxo-5-azaspiro [2.4]-heptane. The method comprises the following steps: adopting raceme (7R, 7S)-amino-5-[1(R)-5-phenethyl] 4-oxo-5-azaspiro [2.4]-heptane as the raw material, and obtaining (7S)-amino-5-[1(R)-5-phenethyl] 4-oxo-5-azaspiro [2.4]-heptane after optical resolution. The method has the advantages that the cost is low, the operation is simple, the reaction is mild, toxic and harmful substances are not used and generated, the yield is high, and the optical purity of the product is high, thereby being suitable for large-scale industrialized production.