Highly Selective Entry to the Azadirachtin Skeleton via a Claisen Rearrangement/Radical Cyclization Sequence

A highly diastereoselective, microwave-induced Claisen rearrangement of an appropriately substituted propargylic enol ether allows the formation of the sterically congested C8−C14 bond of azadirachtin. When combined with a radical-mediated cyclization of the corresponding allene, this sequence offers rapid entry to the framework of azadirachtin.