Convenient synthesis of allenyl sulphides; application to the synthesis of αβ-unsaturated ketones

P2S5 in methylene chloride containing pyridine reduces allenyl phenyl sulphoxides to sulphides; the difficult hydrolysis of the latter is eased by the introduction of a methoxy group into the benzene ring and this method then becomes a practicable synthesis of αβ-unsaturated ketones.