Facile Optical Resolution of a Dibenzopyrazinoazepine Derivative and the Nature of Molecular Recognition of Amines by Chiral 2,3-Di-O-(arylcarbonyl)tartaric Acids

Article abstract of DOI:10.1246/bcsj.69.3581

A facile optical resolution of racemic 1,2,3,4,10,14b-hexahydrodibenzopyrazino<1,2-a>azepine (1) was developed using 2,3-di-O-benzoyl-D-(-)-tartaric acid ((+)-DBT) as a resolving agent.The resolution efficiency depends remarkably on the (+)-DBT:1 ratio.When (+)-DBT and racemic 1 were mixed in methanol-water (9:1 v/v) in a 1:4 stoichiometry, a crystalline salt consisting of (+)-DBT, (R)-1, methanol, and water in a 1:2:2:2 ratio crystallized preferentially in a fair yield.X-Ray crystallographic analysis showed its highly ordered supramolecular structure: (+)-DBT molecules self-assemble via hydrogen bonding with the aid of water and methanol to form a puckered layer, and stacking of (R)-1 molecules constructs a column which is sandwiched in between the puckered layers.The X-ray crystallographic data reported for the salts that consist of amines and DBT were reinvestigated to reveal that most of the host frameworks derived from DBT have a layer structure similar to the above puckered one.