Saturated heterocycles. Part 216 . Synthesis, structure and ring opening of trans ‐perhydro‐1,4‐benzoxazepin‐3‐one derivatives

trans ‐Perhydro‐1,4‐benzoxazepin‐3‐ones 2a‐c were synthesized and transformed to condensed‐skeleton perhydro‐ trans ‐1,4‐benzoxazepines 3a,b , the thiones 4a,b , the urea derivatives 5a,b , and N ‐acylated compounds 6a‐e . Compounds 6b,d were ring‐opened by hydrochloric acid in ethanol to yield trans ‐2‐(1‐carbethoxyethoxy)‐1‐acylaminomethylcyclohexane derivatives 7b,d . The 1 H‐ and 13 C‐nmr investigation and X‐ray analysis of 5b and 6c,d proved that the expected N ‐acylated derivatives were formed and that both rings of the trans anellated compounds have a chair conformation.