NUCLEOPHILIC VINYLIC SUBSTITUTION ON ALPHA-TOSYLOXYMETHYLENE LACTONES

Sodium salt of 3-hydroxymethylenetetrahydro-2H-pyran-2-one (V), obtained by Claisen condensation of delta-valerolactone with ethyl formate, was converted into its sulfonates and carboxylates IV VII - X, which were obtained either as pure E-isomers or as mixtures of E- and Z-isomers; the mixtures were chromatographically separated. Substitution reaction of alpha-tosyloxymethylene lactones II, III and IV with aromatic thiols, azide anion, secondary amines and sodium enolates XI, XII and V was studied. The stereochemical outcome of this substitution is discussed from the viewpoint of mechanism of nucleophilic vinylic substitution (S(N)V).