中文摘要：

以L-酪氨酸为原料合成了化合物1和化合物2，化合物2与NaBH4在THF下回流过夜，还原完毕后加少量水继续回流7～8h就可直接得到关环产物3，总产率为40．8％．在反应体系中，水的存在促进了关环产物的生成，使还原和成环在一个单一的过程中就可完成．

英文摘要：

Compounds 1 and 2 have been synthesized from L - tyrosine. Refluxing a THF solution of compound 2 with NaBH4, after the reduction step was completed,then adding several drops of water and refluxing 7 - 8 h formed oxazolidin - one 3 directly, and total yield of the tree steps was 40.8 %. In our reactions, existing of a little water promoted the cyelization , and made the reduction and eyclization steps be accomplished in a single operation.