An improved and efficient method for synthesis of (lS,4S)-2-oxa-5-azabicyclo[2.2.1]heptane (1) from trans-4-hydroxy-l-proline was developed. Using benzyloxycarbonyl (Cbz) as protection group of amine, the reactions were in mild conditions, and the title compound 1 was accomplished in six steps in overall yield of 70%.

中文翻译：

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（l S，4 S）-2-氧杂-5-氮杂双环[2.2.1]庚烷的改进合成

提出了一种由反式-4-羟基-1-脯氨酸合成（l S，4 S）-2-oxa-5-氮杂双环[2.2.1]庚烷（1）的改进高效方法。用苄氧羰基（Cbz）作为胺的保护基，反应在温和的条件下进行，分六步完成标题化合物1，总收率70％。