ORGANOMANGANESE COMPLEXES IN ORGANIC SYNTHESIS

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Arene manganese tricarbonyl complexes provide an excellent means of synthesizing diaryl ethers under extremely mild conditions. We have explored the application of this technique for preparing diaryl ethers having amino acid side chains, as a model for ristocetin synthesis, and the coupling reaction proceeds without loss of optical activity of the protected amino acid. It is proposed to set in hand a detailed investigation into the synthesis of haloarene-Mn(CO)3 complexes containing funcitonalized substituents and to study the displacement of halide by a range of substituted phenoxides and other nucleophiles. A number of simple but important natural products, such as isomagnolol, cularines, and neothalibrine, will be synthesized to illustrate the usefulness of this technique. Ultimately, manganese complexes will be made available which can be applied to the construction of the novel triaryldiether and diaryl ether amino acid subunits found in the glycopeptide anitibiotics related to ristocetin. A total synthesis of ristocetin is a formidable undertaking, but as a long term objective is extremely important, since these compounds are potentially valuable broad spectrum antibiotics which are useful in the treatment of staphylococcal infections when other antibiotics are ineffective. New methods for carbon-carbon bond formation using triene-Mn(CO)3 and dienyl-Mn(CO)3 complexes will be investigated, with a view to their ultimate application as organic synthesis intermediates. Particular attention will be paid to the use of manganese carbonyl to effect the formation of polyquinane derivatives.