A Selective Intramolecular 5-exo-dig or 6-endo-dig Cyclization en Route to 2-Furanone or 2-Pyrone Containing Tricyclic Scaffolds

Ringfused bicyclic 2-pyridones exhibit interesting biological properties against pili assembly in uropathogenic Escherichia coli (Pinkner, J. S. et al. Proc. Natl. Acad. Sci. U. S. A. 2006, 103, 17897–17902; Åberg, V. et al. Org. Biomol. Chem. 2007, 5, 1827–1834) as well as curli formation (Cegelski, L. et al. Nat. Chem. Biol. 2009, 5, 913–919). In the search for new ring-fused central fragments, highly selective synthetic routes to the 2-furanone or 2-pyrone containing tricyclic scaffolds 1 and 2 have been developed.