Bi- and Tridentate Ligand Libraries: Efficient and Facile "Click" Approach
Written by Elaine M. Schuster
Elaine M. Schuster and Mark Gandelman
Bidentate and tridentate chelating ligands represent an important class of compounds for the construction of transition metal catalysts. In particular, hetero-bidentate ligands, which have two different chelating atoms, have recently received a great amount of attention due their capacity to fine-tune the stereoelectronic properties of the reaction center. As compared to monodentate ligands, however, the synthesis of their poly-dentate counterparts is generally more complex and less efficient. It especially represents a substantial drawback for reactions which require rigorous ligand optimization.
We have developed a novel approach to the fast and efficient preparation of bi-and tridentate ligands. Our strategy utilizes a highly selective cycloaddition of the corresponding monomeric counterparts leading to their covalent assembly as multidentate ligands in solution. To the best of our knowledge, this is the first such approach to the preparation of pincer-type ligand libraries. Numerous late transition metal complexes based on these novel ligands have been prepared and their catalytic properties are discussed.
Schuster, E. Botoshansky, M., Gandelman, M. Angew. Chem. Int. Ed. 2008, 47, 4555.