A full study on the synthesis of 3-azabicyclo[4.1.0]heptane-1-carboxylic acid is described. Three different approaches were investigated in order to achieve an efficient synthesis of this unnatural aminoacid. The optimized synthetic route relies upon three key steps: (i) diazomalonate insertion on 4-phtalimido 1-butene, (ii) intramolecular cyclization and (iii) chemoselective reduction of the resulting lactam. Due to its bicyclic nature and conformational constraints, this aminoacid may be an useful building block in medicinal chemistry.
