Stereochemical Control of Polyketides through Asymmetric Aldol Reaction

Polyketides are a group of complex natural products that can inhibit the growth of bacteria, viruses, fungi, and tumor cells. Most polyketides are very difficult to extract from bacteria. Therefore, numerous syntheses of polyketide-related synthons have been attempted.

However, controlling the stereochemistry of the polyketide poses the most challenging task for researchers. The aim of this report is to discuss control of the stereochemistry of the polyketide-related synthons in asymmetric aldol reactions. Several important methodologies for stereochemical control in the aldol reaction exist. The first approach is to control the enolate geometry and the aldehyde (or ketone) geometry. The second approach is to use a chiral auxiliary and chiral ligands. The third approach is to use a chiral catalyst, which is the most efficient method if the catalyst operates with complete efficiency. Proposed transition states are also described to explain the resulting stereochemistry of the aldol adduct.