Synthesis of chiral nonracemic PC(sp³)P pincer ligands

The manuscript describes a straightforward synthetic route toward a new family of chiral nonracemic dibenzobarrelene-based pincer ligands. The target molecules have been synthesized via lithiation of the racemic 1-bromo-8-diphenylphosphinotriptycene (2) and subsequent quenching with diastereomerically pure (1R,2S,5R)-(-)-menthyl (S)-p-toluenesulfinate. The resulting mixture of diastereomers was resolved using conventional column chromatography. Hydrogenation of the diastereomerically pure compounds lead to the formation of enantiopure PCS ligands.