Boron trifluoride-promoted reaction of benzenesulphenanilides with alkenes in acetonitrile and benzonitrile: amidino- and amido-sulphenylation of alkenes

Abstract

Benzenesulphenanilides (1) react at room temperature with alkenes in acetonitrile or benzonitrile in the presence of boron trifluoride–diethyl ether to give amidino sulphides (5; R = Me, Ph) in fair to good yields together with varying amounts of amido sulphides (7; R = Me, Ph) and arylamino sulphides (4), whereas at 100 °C and in the presence of water 4′-nitrobenzenesulphenanilide affords amido sulphides (7; R = Me, Ph) as the main products. With cyclohexene a high selectivity for trans-addition is observed. With terminal alkenes the terminal sulphides are produced with high regioselectivity. The findings are consistent with a mechanism involving intermediacy of episulphonium ions (3) which result from alkene attack at the sulphur atom of an anllide–BF₃ complex.