Hydroformylation is powerful catalytic reaction capable of converting alkenes directly into aldehydes by addition of a formyl group and hydrogen across the double bond. Installation of the formyl group at an internal carbon establishes a chiral center, and a variety of chiral ligands may be employed to direct the enantioselectivity of the reaction. The alkene substrates are easily accessed, and the resultant aldehydes are common precursors for diverse synthetic manipulations.
This chapter covers enantioselective hydroformylation from its inception, presents the most common metal precursors and ligands, and includes all examples that produce aldehydes with yields above 20% and enantioselectivity above 60:40 er. The initial discussion focuses on the mechanism and stereochemistry, and on the regio- and enantioselectivity-determining steps in particular, as these are crucial for overall yield. The “Scope and Limitations” section is divided by substrate type and offers examples of exceptional catalytic systems that have been reported for each. The application of enantioselective hydroformylation to synthetic procedures is discussed by highlighting some reported examples, comparing it to other protocols that also afford chiral aldehydes, and exploring the standard experimental conditions.
The intention of this review is to demonstrate the power and scope of enantioselective hydroformylation to researchers, and to provide a suitable starting point for those interested in its application to their own synthetic strategies.