Total Synthesis of Kingianin A

A 12-step synthesis of kingianin A, an inhibitor of the antiapoptotic protein Bcl-xL, Is based on a radical cation Diels-Alder reaction (RCDA). This approach is thought to be biomimetic. The use of a tether in the key RCDA step controls the regiochemistry of the cycloaddition, leading to the desired core structure and a separable diastereomer.