Synthesis, resolution, and absolute configuration of optically pure 5,5''-dihydroxy-4',4''',7,7''-tetramethoxy-8,8''-biflavone and its derivatives

Article abstract of DOI:10.1021/jo00125a031

Optically pure 5,5_-dihydroxy-4,4''',7,7''-tetramethoxy-8,8''-biflavone (1) and its dimethyl derivative 5 were synthesized for the first time. Resolution of the racemic (±)-1, prepared by a modified literature procedure, was performed via the formation and recrystallization of its (+)- and (-)-camphorsulfonate 6. Hydrolysis of the (+)- or (-)-camphorsulfonate 6 afforded optically pure (+) or (-)-1, which was then methylated to give (+)- or (-)-5. The absolute configurations of (+)-1 and (-)-1, assigned as (aR) and (aS), respectively, were confirmed in an unambiguous manner by X-ray single crystal analysis and from their CD spectra.