New Applications of Tridentate Bis(oxazoline) Ligands in Asymmetric Catalysis

Finding interactions between microRNAs and their mRNA targets is a challenging experimental and computational problem. While several novel experimental high throughput approaches have been developed for measuring miRNA expression, the amount of data generated from these technologies is dwarfed by the amount of data existing in current gene expression microarray repositories. Many microRNAs overlap with or map very close to the genomic coordinates of probesets in gene expression microarrays and have expression levels that are highly correlated with these probesets. We found that some Affymetrix expression chips have probeset coverage of up to 65% of the known micoRNAs in mammalian genomes. Combining this information with computationally predicted mRNA targets of the same microRNAs: we developed a tool (miGraph) to predict differentially expressed microRNAs and their differentially regulated mRNA targets from gene expression microarray data. We use this to generate bipartite graphs of potential microRNAmRNA co-expression networks. We applied this technique to a thyroid cancer dataset and show excellent agreement with direct experimental measurement of microRNA expression. This method appears to be very useful in picking out highly relevant sub networks of microRNAs and their target genes. We identify two such potential sub-networks in published brain data sets. New Oxazoline-containing Ligands for Asymmetric Catalysis Mc Keon, Sean, Guiry, Patrick*. Centre for Synthesis and Chemical Biology, School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland. Email: [email protected] Asymmetric metal catalysis is an effective and efficient method of preparing enantiopure compounds. The asymmetry of a metal-catalysed process is controlled by the organic groups bound to the metal, as they control the binding of the reactants and their reaction paths through steric and electronic interactions. Chiral tridentate ligands are believed to form a deeper concave pocket around the metal centre. The oxazoline unit has been used successfully in a wide range of metal-catalysed asymmetric transformations and the tridentate example 1 has been prepared within the Guiry research group. During that study, non-C2-symmetric examples (R ≠ R) were found to induce optimal enantioselectivities in the Cr-catalysed Nozaki-Hiyama Kishi (NHK) reaction. This poster describes the synthesis of non-C2-symmetric ligand classes 1 and 2. These ligands offer a further electronic desymmetrisation, which is hoped to increase the enantiometric excess achieved in metal catalysed asymmetric transformations. (1) Catalytic Asymmetric Synthesis, 2nd Edition, Ed. Oijiama, I. Wiley-VH, New York, 2000. (2) McManus, H. A.; Guiry, P. J. Journal of Organic Chemistry 2002, 67, 8566. (3) Mc Manus, H. A.; Guiry, P. J. Chem. Rev. 2004, 104, 4151-4202. N