The Vilsmeier reagent as an efficient acid activator for the synthesis of β-lactams

The Vilsmeier reagent (chloromethylenedimethylammonium chloride) has been used as an efficient and cheap acid activator for the one-step Staudinger reaction of substituted acetic acids and imines under mild conditions. This reaction is clean and the by-products are DMF and triethylamine hydrochloride which were removed by simple aqueous work-up.