2  Synthetic methods : Part (ii) Oxidation and reduction methods

As in last year's account, this Report highlights advances in some of the most commonly used oxidation and reduction reactions, focusing on the literature from 2004. Significant advances in oxidation chemistry include the first high enantioselectivities in iminium salt-catalysed alkene epoxidations (Scheme 1); new reaction conditions with broader scope and further mechanistic insight into polyleucine-mediated nucleophilic epoxidation; and proline-catalysed α-aminoxylation of ketones (Scheme 10). Amongst highlights in reduction chemistry are the accomplishment of direct asymmetric hydrogenation of unprotected β-enamine esters (Scheme 12); new iridium catalysts 16–19 for asymmetric hydrogenation of unfunctionalized trisubstituted alkenes (Scheme 13); and effective asymmetric conjugate reduction reactions promoted by copper (Scheme 16) and by organocatalysts (Scheme 17).