Resolution of racemic gossypol.

Treating racemic gossypol with chiral amine (S)-1-methylphenethyl amine gave the expected pair of diastereomeric amino condensates in which the binaphthyl nuclei racemized during further treatment. Acetylation was applied to avoid the change. On acetylation, 7 products were separated. Their structures were assigned based upon their spectroscopic data. After hydrolysis they gave optically active (+)- and (-)-gossypol correspondingly. A simple and practical method of quick separation of the diastereomers was also discussed.