Synthesis, resolution and reactions of (±)-1-(dimethylarsino)-2-(methylphenylphosphino)benzene. Crystal and molecular structure of [(S), (S)]-(+)589-{2-[1-(dimethylamino)ethyl]phenyl-C1,N}[1-(dimethylarsino)-2-(methylphenylphosphino)benzene-As,P]palladium(II) hexafluorophosphate

Abstract

Asymmetric bidentate (±)-1-(dimethylarsino)-2-(methylphenylphosphino)benzene has been prepared by the reaction of sodium dimethylarsenide with (±)-1-chloro-2-(methylphenylphosphino)benzene in tetrahydrofuran. Its resolution has been achieved by the separation by fractional crystallisation of a pair of internally diastereomeric palladium(II) complexes containing the racemic ligand and orthometallated (S)-dimethyl(1-phenylethyl)amine. The optically pure antipodes have α±32°(589 nm, dichloromethane). The absolute configuration of the R enantiomer of the ligand has been assigned by a crystal-structure determination of the least-soluble diastereomeric complex [(S),(S)]-(+)₅₈₉-{2-[1-(dimethylamino)ethyl]phenyl-C¹, N}[1-(dimethylarsino)-2-(methylphenylphosphino)benzene-As,P]palladium(II) hexafluorophosphate. Chemoselective cleavage of the dimethylarsino moiety of the free benzene derivative occurs in the presence of lithium metal in tetrahydrofuran.