Optically Active Triptycenes. II. Synthesis of Optically Active 7-Substituted 2,5-Dimethoxytriptycenes

A series of optically active 7-substituted 2,5-dimethoxytriptycenes has been prepared from (+)-2,5-diacetoxy-7-carboxytriptycene (I) as suitable model compounds for a study of the relationship between their structure and optical rotatory properties. The single crystal of 2,5-dimethoxy-7-dimethylaminotriptycene hydrobromide (VII) thus prepared was subjected to X-ray crystallographic analysis and proved to have 1R, 6S absolute configuration. Consequently, it became clear that all compounds of this series have the same 1R, 6S configuration. They showed without exception positive optical rotation in visible wavelength region.