Asymmetric Synthesis via Chiral Transition Metal Auxiliaries

Stoichiometric reagents for the control of the absolute stereochemistry of new chiral centres produced during reactions involving carbon--carbon bond formation are described. Chiral iron acyl reagents act as chiral equivalents of a variety of carbonyl functionalities and their potential for asymmetric synthesis can be illustrated for pseudopeptides, amino acids, β -lactams, γ -lactams and lactones. A simple methodology based on arene chromium tricarbonyl chemistry allows the elaboration of benzylic chiral centres with complete control over the absolute stereochemistry. This may be illustrated, for example, by the conversion of amphetamine derivatives into pseudoephedrines.