The crystal structure of 1,5-bis(3,5-dimethyl-2-hydroxybenzyl)-1,5-diazocan-2,6-dione

The study of the molecular geometry of 1,5-bis(3,5-dimethyl-2-hydroxybenzyl)-1,5-diazocan-2,6-dione (2) as determined by X-ray analysis is reported and compared with that of cyclodi-β-alanyl (3). Interestingly there are 1.5 molecules of 2 in the asymmetric unit, showing the two conformations (1 twist-boat- and 0.5 chair-type) with two parallel aromatic rings (from alternate twist-boat conformers) sandwiching the eight-membered ring of the centrosymmetric chair-type conformation. The twist-boat is shown by pmr spectroscopy to be the only significantly populated conformer at low temperature in deuteriodichloromethane solution.