Efficient oxidative resolution of a P-stereogenic triarylphosphine and asymmetric synthesis of a P-stereogenic atropoisomeric biphenyl diphosphine dioxide
摘要:
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. (C) 2010 Elsevier Ltd. All rights reserved.
Efficient oxidative resolution of a P-stereogenic triarylphosphine and asymmetric synthesis of a P-stereogenic atropoisomeric biphenyl diphosphine dioxide
摘要:
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. (C) 2010 Elsevier Ltd. All rights reserved.