Efficient oxidative resolution of a P-stereogenic triarylphosphine and asymmetric synthesis of a P-stereogenic atropoisomeric biphenyl diphosphine dioxide

Racemic 3-methoxyphenyl(1-naphthyl)phenylphosphine 1 was effectively resolved via an oxidative resolution procedure utilizing l-menthyl bromoacetate as the resolving agent to give enantiopure 3-methoxyphenyl(1-naphthyl)phenylphosphine oxide (R)-2 in 41% yield. Reduction of the resolved (R)-4 with HSiCl₃/NEt₃ provided the corresponding phosphine (R)-1 in >97% ee. Ortho-iodination of the enantiopure (R)-4 followed by Ullmann coupling of the resulting iodoarylphosphine oxide gave a P-stereogenic and atropoisomeric biphenyl diphosphine dioxide as a single diastereoisomer. The latter transformation constitutes the first example of an effective transfer of a P-centered chirality to an axial chirality of the atropoisomeric biaryl system. The absolute configurations of the resolved phosphine and the atropoisomeric biaryl system have also been established.