ARENE ACTIVATION BY TRANSITION METALS

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Arenemanganese tricarbonyl and arene(cyclopentadienyl)ruthenium complexes have been demonstrated to be useful precursors for the construction of diaryl ethers in which both aromatic rings carry protected amino acid side chains. The major thrust of the proposed research is the development of this new methodology towards the synthesis of heptapeptide arylethers related to the glycopeptide antibiotics vancomycin and ristocetin A, which are potentially useful against gram-positive bacteria. A series of simplified polycyclic peptide/aryl ethers will be synthesised and their binding to simple peptides, such as Ac-D-Ala-D-Ala and Ac2-L-Lys-D-Ala-D-Ala, which represent bacterial cell wall precursors, will be studied. Information relating to the minimum structural requirements for significant binding interaction will be thus obtained. Parallel studies on the broader applications of arene-iron and arene-ruthenium complexes will be carried out, since these complexes promise to offer a means of constructing certain aryl ethers that are not available using the organomanganese chemistry. The two important chemical reactions to be employed in all of these studies are (1) addition of phenoxides to a haloarene-metal complex, followed by (2) addition of chiral glycine enolate equivalents to the aryl ether metal system that results from the first reaction. Application of arene-ruthenium complexes in the synthesis of dityrosine derivatives and the antibiotics bouvardin, K-13, and OF 494-III will also be examined.