Pure Appl. Chem., 2006, Vol. 78, No. 2, pp. 249-256
doi:10.1351/pac200678020249
Self-assembly of bidentate ligands for combinatorial homogeneous catalysis based on an A-T base pair model*
Bernhard Breit and Wolfgang Seiche
Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, 79104 Freiburg, Germany
Abstract:
A new concept for generation of chelating ligand libraries for homogeneous metal complex catalysis based on self-assembly is presented. Thus, self-assembly of structurally simple monodentate ligands in order to give structurally more complex bidentate ligands is achieved employing hydrogen bonding. Based on this concept and on the 2-pyridone/hydroxypyridine tautomeric system, a new rhodium catalyst was identified which operated with excellent activity and regioselectivity upon hydroformylation of terminal alkenes. In order to generate defined unsymmetrical heterodimeric ligands, an A-T base pair analog-the aminopyridine/isoquinolone system-was developed which allows for complementary hydrogen bonding. Based on this platform, a 4 x 4 phosphine ligand library was screened in the course of the rhodium-catalyzed hydroformylation of 1-octene. A catalyst operating with outstanding activity and regioselectivity in favor of the linear aldehyde was discovered.
Keywords: 2-hydroxypyridine; 2-pyridone; 6-DPPon; bidentate ligands; BINAP; combinatorial; homogeneous catalysis; hydroformylation; rhodium catalyzed; XANTPHOS.
*Pure Appl. Chem. 78, 197-523. An issue of reviews and research papers based on lectures presented at the 13th IUPAC International Symposium on Organometallic Chemistry Directed Towards Organic Synthesis (OMCOS-13), Geneva, Switzerland, 17-21 July 2005.