An intramolecular nucleophile-catalyzed aldollactonization (ncal) reaction of s-Aryl-(e)-6-oxohex-2-enethioate with n,n-4-dimethylaminopyridine N-oxide

We have developed an intramolecular nucleophile-catalyzed aldollactonization (NCAL) reaction of S-Aryl-(E)-6-oxohex-2-enethiolate with N,N-4-dimethylaminopyridine N-oxide (DMAPO) to afford densely functionalized bicyclic β-lactones in moderate yield. This unique transformation may be explained in terms of nucleophilic substitution of the S-Aryl moiety by DMAPO, followed by 1,4-Addition of aryl thiolate to generate a zwitterionic enolate and an intramolecular C-C bond-forming reaction (aldol-lactonization).