Synthesis of 3‐Azabicyclo[3.2.0]heptane Derivatives as γ‐Aminobutyric Acid Analogues through Intermolecular [2+2] Photocycloaddition

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.