In an effort to improve and simplify the synthetic route to tetronic acids 15 differently substituted β-keto esters were investigated as potential starting materials. The β-keto esters were brominated and cyclised with 2· 5 N KOH as cyclising agent. Tetronic acid and seven derivatives including the naturally occuring carolinic acid were obtained. In a number of cases products arising from a Favorskii rearrangment were isolated. The NMR ...
[Roser Justus Liebigs Annalen der Chemie, 1883 , vol. 220, p. 255 Full Text Show Details Schleicher Justus Liebigs Annalen der Chemie, 1892 , vol. 267, p. 115]