Resolutions Involving Metal Complexation. Preparation and Resolution of (R,S)-Methylphenyl(8-quinolyl)phosphine and Its Arsenic Analogue. Crystal and Molecular Structure of (+)589-[(R)-Dimethyl(1-etliyl-α-naplithyl)aminato-C2, N]-[(S)-methylphenyl(8-quinolyl)phosphine]palladium(II) Hexafluorophosphate

Abstract

The asymmetric bidentates (R,S)-methylphenyl(8-quinolyl)phosphine and (R,S)-methylphenyl(8-quinolyl)arsine have been prepared in high yield from 8-chloroquinoline and the respective substituted phosphide or arsenide anion in tetrahydrofuran at −78 °C. Both compounds are air-stable crystalline solids. An efficient and large-scale resolution of both substances is described, which is based upon the fractional crystallization of a pair of internally diastereoisomeric palladium(II) complexes containing the chiral chelating ligand and an optically active ortho-metalated dimethyl(1-ethyl-α-naphthyl)amine. The optically pure enantiomers of the tertiary phosphine have [α]D ±107° (mp 98 °C) and the corresponding arsine [α]D ±115° (mp 75–76 °C) in diethyl ether solution. The molecular structure and absolute configuration of (+)589-[(R)-dimethyl-(1-ethyl-α-naphthyl)aminato-C2, N][(S)-methylphenyl(8-quinolyl)phosphine]palladium(II) hexafluorophosphate has been determined by a single-crystal X-ray analysis. The complex crystallizes in space group P212121 with a = 25.784 (5) Å, b = 19.159 (3) Å, c = 12.277 (2) Å, and Z = 8. The structure was solved by heavy-atom methods and refined by least-squares methods to an R of 0.079 and Rw of 0.047 for 2955 reflections. The tertiary phosphine liberated from this complex, [α]D −107° (diethyl ether), accordingly has the R absolute configuration. Show more