Facile synthesis of β,β′-diketophosphine sulfides from imines and Lawesson’s reagent

In a convenient one-pot sequence, treatment of imines with Lawesson’s reagent (LR) followed by hydrolytic work-up leads to β,β′-diketophosphine sulfides in good to excellent yields. These compounds were isolated exclusively in their tautomeric β-keto-β′-enol form as was evident from IR and NMR spectroscopic data.