Since the discovery of the cerium-catalyzed α-hydroxylation of β-dicarbonyl compounds 1 (Scheme 1) this reaction has been utilized as a racemic method for natural product synthesis. Despite intensive efforts to establish a catalytic, asymmetric version by application of chiral ligands, today only stoichiometric methods, e.g. with optically active oxaziridines are available. Hence, objective of the project is the development of new chiral ligands for asymmetric cerium-catalyzed reactions, e.g. based on a C2-symmetric bis-imidazoline scaffold.
 a) J. Christoffers, T. Werner, S. Unger, W. Frey, Eur. J. Org. Chem. 2003, 425-431; b) J. Christoffers, T. Werner, Synlett 2002, 119-121; c) Review: J. Christoffers, A. Baro, T. Werner, Adv. Synth. Catal. 2004, 346, 143-151.
 a) J. Christoffers, T. Werner, W. Frey, A. Baro, Chem. Eur. J. 2004, 10, 1042-1045; b) Y. Wu, C. Du, C. Hu, Y. Li, Z. Xie, J. Org. Chem. 2011, 76, 4075–4081; c) Z.-H. Chen, Y.-Q. Zhang, Z.-M. Chen, Y.-Q. Tu, F.-M. Zhang, Chem. Commun. 2011, 47, 1836–1838; d) Y.-M. Zhao, P. Gu, Y.-Q. Tu, C.-A. Fan, Q. Zhang, Org. Lett. 2008, 10, 1763–1766.
 a) J. Lie, G. Chen, Z. Wang, R. Zhang, X. Zhang, K. Ding, Chem. Sci. 2011, 2, 1141–1144; b) S.-H. Cao, M. Shi, Tetrahedron: Asymm. 2010, 21, 2675–2680; c) J.-J. Jiang, J. Huang, D. Wang, M.-X. Zhao, F.-J. Wang, M. Shi, Tetrahedron: Asymm. 2010, 21, 794–799;
 M. Schulz, J. Christoffers, Eur. J. Org. Chem. 2013, 7624–7630.