Then the protected D-mannitol, mixed with lead tetraacetate, hippuric and acetic anhydride, were refluxed in THF for 18 h in a one-pot two step reaction to afford a chiral precursor (Z)-2-phenyl-4-[(S)-2,3-O-(isopropylidene)]-propylidene-5(4H)-oxazolones.

• 产物与四乙酸铅、马尿酸、乙酐于THF中回流18 h完成一釜二步反应，纯化后得到含有手性碳原子的环丙烷氨基酸前体(Z)-2 苯基-4-[(S)-2，3-O-(异丙叉)]丙叉?f唑-5-酮，前体中的手性碳原子可作为环丙烷氨基酸衍生物不对称合成的手性源；