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. (C) 2013 Elsevier B. V. All rights reserved.