The synthesis of optically active P-phenyl-P-(2,4,6-trimethylphenyl)phosphinamide and an X-ray structure of (–)-(1R)-N-(1-phenylethyl)(SP)-P-phenyl-P-(2,4,6-trimethylphenyl)phosphinamide

Abstract

The primary phosphinic amide P-phenyl-P-(2,4,6-trimethylphenyl)phosphinamide has been prepared in optically active form (75% enantiomeric excess) in six steps from dichlorophenylphosphine. The configuration of the intermediate N-(1-phenylethyl)-P-phenyl-P-(2,4,6-trimethylphenyl)phosphinamide has been established by an X-ray crystal structure determination of the minor diastereoisomer. This compound exhibits in the solid state two independent rotameric conformations about the P–N bond. Geometry optimisation by MNDO MO calculations refined these to the same rotamer having the nitrogen lone pair anticlinal to the P–O bond.