DAST-mediated cyclization of α,α-disubstituted-α-acylaminoketones: efficient and divergent synthesis of unprecedented heterocycles.

The design of a new potent nonsteroidal ecdysone agonist led to the discovery of a diethylaminosulfur trifluoride (DAST)-mediated cyclization of α,α-disubstituted-α-acylaminoketones. The resulting fluorooxazolines can be ring-opened or selectively substituted by a range of nucleophiles to provide in high yields a diverse array of unprecedented heterocyclic frameworks.