Ring Opening of 1‐Azabicyclo[1.1.0]butanes with Hydrazoic Acid – a Facile Access to N‐Unsubstituted Azetidin‐3‐Amines

Sterically congested 1‐azabicyclo[1.1.0]butanes 1 add hydrazoic acid smoothly at 0–5°, giving 3‐azidoazetidines 2 in good to excellent yields. After hydrogenolysis over Pd/C catalyst, compounds 2 were converted into N ‐unsubstituted azetidin‐3‐amines 4 . Attempted reduction of 2a with Raney ‐Ni led to a mixture of the expected azetidin‐3‐amine 4a and the ring‐enlarged 2,5‐dihydro‐1 H ‐imidazole derivative 5 .