Tartaric Acid, off the Shelf Building Block for the Construction of New Chiral Transition Metal Complexes and Molecular Cages/Wires and their Further Use in Asymmetric Catalysis

• Applicant: Professor Dr. Rolf W. Saalfrank
• Subject Area: Organic Molecular Chemistry - Synthesis and Characterisation
• Term: from 2002 to 2008
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5382997

In the past, many milestones have been attained in the field of metal complexation by organic ligands leading either to highly enantioselective catalysts or to supramolecular assemblies with interesting properties. In this proposal we envisage the synthesis of new chiral transition metal complexes starting from the less expensive chiron tartaric acid. Chiral precursors like diols, diamines, and aminoalcohols therefore need to be synthesised, and recently, the related chemistry has been well established in our laboratories. The condensation of these chiral building blocks with aldehydes, nitriles, or carboxylic acids followed by complexation with various transition metals leads to new salen, bi(oxazoline), or phenolic oxazoline complexes. The tuning of these transition metal systems for optimising the enantioselectivity given by is easily performed by modifying the substitution pattern of the chiral unit or of the condensation product. Few reactions catalysed by complexes were already carried out in our laboratories viz., enantioselective epoxidation and cyclopropanation of olefins. A broad spectrum of reactions should also be catalysed by such transition metal complexes with interesting asymmetric induction, for example: the nucleophilic substitution of allylic acetates, the hydrolytic kinetic resolution of racemic epoxides, Diels-Alder, et cetera. In addition, such transition metal complexes, due to their numerous complexation sites, should also lead to new supramolecular aggregates. The condensation of diols or diamines with 1,3-diketone equivalents should give chiral bis-1,3-diketone ligands. These compounds, owing to their extra heteroatom donors, are promising candidates for the design of metallacoronands and cryptates. These complexes should lead to enantiomerically pure, helical molecular cages or to chiral, one-dimensional oxo-bridged metal strings. Equally, the potential of as catalysts for asymmetric catalysis will be studied. Furthermore, the introduction of supplementary complexation units at the ether functions should lead to a new class of catalysts for asymmetric catalysis, generated by self-assembly.

• DFG Programme: Research Grants
• International Connection: France
• Participating Person: Dr. Andreas Scheurer