The synthesis of 3-azabicyclo[3.2.0]heptane-6-carboxylic acid and 7-substituted derivatives was developed as bicyclic analogues of γ-aminobutyric acid. A sensitized, intermolecular [2+2] photocycloaddition of maleic anhydride with N-protected 3-pyrroline served as the key step in these syntheses. Upon transformation of the anhydride function of the primary cycloaddition product, 6-monosubstituted and 6,7-disubstituted 3-azabicyclo[3.2.0]heptane derivatives were obtained.

中文翻译：

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通过分子间[2+2]光环加成合成作为γ-氨基丁酸类似物的3-氮杂双环[3.2.0]庚烷衍生物

3-氮杂双环[3.2.0]庚烷-6-羧酸和7-取代衍生物的合成被开发为γ-氨基丁酸的双环类似物。马来酸酐与 N 保护的 3-吡咯啉的敏化、分子间 [2+2] 光环加成反应是这些合成中的关键步骤。在转化初级环加成产物的酸酐官能团后，获得了 6-单取代和 6,7-二取代的 3-氮杂双环 [3.2.0] 庚烷衍生物。