Preparation and structural elucidation of (−)-tetrahydroberberine-(+)-2,3-di(p-toluyl) tartaric acid complex

A new (2:1) complex of (−)-13aS-tetrahydroberberine [(−)-13aS-THB] with (+)-2,3-di(p-toluyl) tartaric acid (DTTA), i.e. 5,8,13,13a-tetrahydro-9,10-dimethoxy-2,3-methylenedioxy-6H dibenzo[a,g] quinolizine·2,3-di(p-toluyl) tartaric acid [2C20H20NO4·C20H18O8], as well as its optical active component (−)-THB, has been obtained from the resolution process of (±)-THB in methanol. The structures of this complex and an enantiomer (−)-13aS-THB have been characterized by CD, IR and NMR spectroscopy as well as by X-ray single crystal diffraction.