A first optical resolution of 6,12-diphenyldibenzo[b,f][1,5]diazocine with stable boat conformation was achieved by chiral supercritical fluid chromatography (SFC). The absolute configurations of enantiomers were first assigned and determined by X-ray crystal structure based on CIP-rules. The high optical rotation and circular dichroism spectrum were well explained by electronic helix theory. Owing to the high stabilization of boat conformation, the chiral configuration could be maintained at very high temperature, more than 200 °C, which was proved by Density Functional Theory calculations.

The title compound, C19H16F4O4, was prepared by the condensation reaction of 2,6-di­fluoro­benzaldehyde and penta­erythritol. The whole mol­ecule is generated by twofold rotational symmetry. The two six-membered O-heterocycles adopt chair conformations through a shared spiro-carbon atom that is located on the crystallographic twofold rotation axis. In this conformation, the two aromatic rings are located at the equatorial positions of the O-heterocycles. The conformation of this doubly substituted tetra­oxa­spiro system is chiral. In the crystal, mol­ecules are linked by C—H⋯O hydrogen bonds, forming layers parallel to (100). These layers are linked by C—H⋯F hydrogen bonds into a three-dimensional structure.

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