Synthesis of Azaphilones and Related Molecules by Employing Cycloisomerization of o‐Alkynylbenzaldehydes

Right to the core: Gold(III)-catalyzed cycloisomerization of o-alkynylbenzaldehydes to 2-benzopyrylium salts and subsequent in situ oxidation have been employed to prepare the core structure of azaphilone natural products, such as the sphingosine kinase inhibitor S-15183 (see scheme, DCE=1,2-dichloroethane, TFA=trifluoroacetic acid)), and several unnatural azaphilones.