Indium-mediated regio- and chemoselective synthesis of alpha-hydroxyalkyl allenic esters and gold-catalyzed cyclizations to ethyl 2-naphthoate derivatives.

The regio- and chemoselective synthetic method of functionalized alpha-hydroxyalkyl allenic esters was developed from the reactions of various aldehydes with organoindium reagent generated in situ from indium and ethyl 4-bromobutynoate. The alpha-hydroxyalkyl allenic esters possessing electron-donating groups were cyclized to ethyl 2-naphthoate derivatives through intramolecular C-alkylation catalyzed by gold salts.