| Resumo: | <p>This thesis describes the application of (arene)Cr(CO)3 methodology to the Stereoselective and enantioselective synthesis of substituted arenes. Chapter one reviews the main methods of preparation and decomplexation of (arene)Cr(CO)<sub>3</sub> complexes and the electronic and steric influences of the Cr(CO)<sub>3</sub> unit on the arene.</p> <p>Chapter two demonstrates that the benzylic oxygen directing effect in complexation reactions operates <em>via</em> a direct oxygen bond to the incoming metal unit. Attachment of bulky ft-acceptor groups, such as t-butyldimethylsilyl, to the benzylic oxygen overrides this directing effect.</p> <p>Chapter three describes the regioselective Cl functionalisation of the cryptopine skeleton. Complexation of dihydrocrytopine gives only a single product, the relative configuration of the product being determined using an X-ray crystal structure analysis. Subsequent alkylation of the O-methyl derivative gives Cl alkylated products.</p> <p>Chapter four describes the regioselective <em>ortho</em> functionalisation of ephedrine and pseudoephedrine derivatives. Treatment of (1S,2R)-(N,O-dimethylpseudoephedrine) Cr(CO)<sub>3</sub> with <em>n</em>-butyllithium leads to exclusive removal of the <em>pro-(R) ortho</em> proton. The observed stereoselectivity arises <em>via</em> <p>Chapter five describes the regioselective C4 and C5 functionalisation of (hydrocotarnine)Cr(CO)<sub>3</sub>. Complexation of 1-methylhydrocotarnine occurs to give exclusively the <em>exo</em>-1-methyl derivative. Further functionalisation to give the 1,5- and 4,5-dimethyl products is also described.</p> <p>Chapter six describes the synthesis of <em>ortho</em> substituted (benzaldehyde)Cr(CO)<sub>3</sub> complexes. Chiral material is available via preferential kinetic hydrolysis of, or classical separation of, the L-valinol derived imines.</p> <p>Chapter seven describes the Stereoselective addition of nucleophiles to (<em>o</em>-anisaldehyde) Cr(CO)<sub>3</sub> and (o-trialkylsilylbenzaldehyde)Cr(CO)3. With (<em>o</em>-anisaldehyde)- Cr(CO)<sub>3</sub> the additions are completely stereoselective giving the (<em>RR,SS</em>) diastereoisomer. With (<em>o</em>-trialkylsilylbenzaldehyde)Cr(CO)<sub>3</sub> the ratio of products is influenced by the nature of Lewis acidic species present.</p> <p>Chapter eight describes the Stereoselective benzylic elaboration of (<em>o</em>-methoxybenzyl methyl ether)Cr(CO)<sub>3</sub> achieved via selective removal of the <em>exo</em> benzylic proton from transition states with the methoxy groups <em>anti</em> to each other.</p></p>
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