Optical resolution of racemic stilbenediamine using N*-chiral ortho-palladated matrix

Optical resolution of racemic stilbenediamine (Stien) was performed by recr ystallization of its diastereomeric adducts with ortho-palladated (S)-N-iso propyl-alpha-methylbenzylamine. The less soluble (SCRN,SS) diastereomer was studied by X-ray diffraction analysis. It was established that the crystal of this diastereomer consists of dimers formed via association of two mole cules of the mononuclear cationic complex with an additional molecule of fr ee diamine of the same absolute configuration. The association occurs throu gh a system of hydrogen bonds and weak agostic interactions. Based on the X -ray diffraction data, the procedure was improved for the resolution of sti lbenediamine due to the more profitable use of the ortho-palladated reagent . The Stien/Pd ratio in the diastereomer isolated was increased up to 3 : 2 . The conformational features of the complex are discussed on the basis of H-1 NMR spectroscopy data.