Formation of gamma-lactones through CAN-mediated oxidative cleavage of hemiketals.

The generation of substituted gamma-lactones can be accomplished through application of a tandem chain extension-aldol reaction, followed by CAN-mediated oxidative cleavage of the aldol product. The oxidative cleavage requires the intermediacy of a hemiketal and the presence of an alpha-heteroatom. Formation of the gamma-lactone through the oxidative cleavage is used to assign stereochemistry of the aldol reaction and as the final step in a short synthesis of members of the phaseolinic acid family of natural products.