Synthesis of perhydro‐2(1 H )‐quinoxalinones and perhydropyrrolo[1,2‐ a ]quinoxalin‐4(5 H )‐one derivatives

The novel trans ‐bicyclic‐perhydro‐2(1 H )‐quinoxalinones 4, 6 and 7 and the tricyclic‐perhydropyrrolo[1,2‐ a ]‐quinoxalin‐4(5 H )‐one derivatives 8 and 9 are prepared via a ring opening and spontaneous ring closing reaction of the aziridines 2 and 3 with the α‐amino acids glycine, L‐alanine, L‐proline and L‐phenylalanine. This methodology was used to prepare 5 and 10 which are novel rigid analogues of the kappa opioid compound 1. Treatment of aziridine 3 with methyl carbamate gave the cyclic urea 11.