Here we report an efficient one‐pot procedure for the preparation of functionalized azabicyclo[6.3.0]alkanone amino acid derivatives. The synthetic protocol exploits an ethylene‐mediated cross enyne metathesis followed by a ring closing metathesis. The reactivity of the newly synthesized 8,5‐fused bicyclic scaffolds has then been investigated to obtain variously functionalized derivatives with potential applications in the field of peptides/peptidomimetics.