Au(III)-Catalyzed Synthesis of Polysubstituted Halofurans

Siginificance

Au(III)-catalyzed selective cyclo-isomerization of haloallenyl ketones to 3-halofurans is reported. The reaction proceeds in good to excellent yields (44-97%) under mild conditions for a variety of substituted haloallenyl ketones with diverse functionalities. This method allows the synthesis of halofurans possessing hydroxymethyl and alkene functionalities, which could not be derived by known methods of furan synthesis employing electrophilic reagents. A mechanism via a halirenium intermediate and involving a 1,2-migration of halogen is proposed.