The synthesis of 1,3,4,5‐tetrahydro‐2,3‐benzoxazepines and 1,2,4,5‐tetrahydro‐3,2‐benzoxazepines

Condensation of o ‐bromomethylphenethyl bromide with potassium salt of N ‐hydroxyurethan afforded 3‐earbethoxy‐1,3,4,5‐tetrahydro‐2,3‐benzoxazepine, which was hydrolyzed to 1,3,4,5‐tetrahydro‐2,3‐benxoxazepine (III). The reaction of o ‐aeetoxymethylphenethyl bromide (VIb) with potassium salt of N ‐hydroxyurethan in DMF, gave a complex mixture, from which O ‐[2‐( o ‐acetoxymethylphenyl)(ethyl]‐ N ‐earbethoxyhydroxylamine (VIIa) was separated. Subsequent desacetylation to VIIb and halogenation yielded O ‐[2‐( o ‐bromomethylphenyl)ethyl]‐ N ‐carbethoxyhydroxylamine (VIIc). By treatment of VIIc with potassium hydroxide, 2‐carbethoxy‐1,2,4,5‐tetrahydro‐3,2‐benzoxazepine (X) was obtained together with small amounts of 6,15‐diearbethoxy‐5,6,8,9,14,15,17, 18‐octahy drodibe nzo[ d,I ]‐1,8‐dioxa‐2,9‐diazaeyclotetradec in e (XI). Hydrolysis of X with potassium hydroxide gave 1,2,4,5‐tetrahydro‐3,2‐benzoxazepine (XII). N ‐Alkyl and N ‐acyl derivatives of III and XII were also prepared.