Functionalization of phospha-thiahelicenes and application of their gold(I) complexes in enantioselective catalysis

Helically chiral structures are known to display peculiar properties and applications in many fields, including asymmetric catalysis. However, both the synthesis of helical phosphorus ligands and their uses in enantioselective organometallic catalysis have been underdeveloped so far [1]. In the course of our studies on helical phosphane derivatives as potential chiral ligands in asymmetric organometallic catalysis [2], we have recently reported the synthesis of a new chiral phospha-thiahelicene based gold (I) complex, which is an excellent and selective pre-catalyst for the enantioselective cycloisomerization of N-tethered enynes [3]. On the basis of these very promising results we have effectively functionalized the phospha-thiahelicene scaffold to obtain new gold (I) complexes, which are then tested as pre-catalysts in other challenging enantioselective cycloisomerization reactions. 1. a) Y. Shen, C.-F. Chen, Chem. Rev. 2012, 112, 1463; b) P. Aillard , A. Voituriez, A. Marinetti, Dalton Trans. 2014, 43, 15263. 2. a) S. Cauteruccio, A. Loos, A. Bossi, M. C. Blanco Jaimes, D. Dova, F. Rominger, S. Prager, A. Dreuw, E. Licandro, A. S. K. Hashmi, Inorg. Chem. 2013, 52, 7995; b) K. Yavari, P. Aillard, Y. Zhang, F. Nuter, P. Retailleau, A. Voituriez, A. Marinetti, Angew. Chem. Int. Ed. 2014, 53, 861. 3. P. Aillard, A. Voituriez, D. Dova, S. Cauteruccio, E. Licandro, and A. Marinetti, Chem. Eur. J. 2014, 20, 12373.