The boron trifluoride-catalysed reaction of furan derivatives with ethane-1,2-dithiol

Abstract

Treatment of furan, 3-isopropylfuran, benzofuran, and the diterpene 3-ketomarrubiin with ethane-1,2-dithiol in the presence of boron trifluoride–ether complex gives 2,5-(or 2,3-)dihydro-2-(2-mercaptoethylthio)furan derivatives. Similar treatment of furfuryl alcohol gives the corresponding 2-mercaptoethyl thioether, and furfural gives the corresponding thioacetal, but ethyl 2-furoate and 2-nitrofuran remain unaltered. The addition reaction is considered to occur through nucleophilic attack of a thiol group on the 2-position of a boron trifluoride-co-ordinated furan nucleus.