Solvent-free, one-pot synthesis of beta-lactams by the Sc(OTf)(3)-catalyzed reaction of silyl ketene thiocetals with imines

A solvent-free, catalytic, one-pot synthesis of -lactams is described. The reaction involves the reaction between silyl ketene thioacetals derived from 2-pyridyl thioesters and imines at room temperature in the presence of catalytic amounts of Sc(OTf)3 and in the absence of solvent. Extension of this procedure to the synthesis of an enantiomerically pure azetidinone, a precursor of industrially relevant bioactive -lactams, is also reported.