Réactions de Friedel et Crafts de dérivés aromatiques sur les composés dioxo‐1,4,2,3‐non saturés. IV. Réactions des hydroxy‐5‐ouchloro‐5‐diméthyl‐3,5‐ ou diméthyl‐4,5‐dihydro‐2,5‐furannones‐2

Friedel-Craftsreactions of aromatic derivatives with 1,4-dicarbonyls 2,3-ethylenic compounds. Part IV. Reactions of 5-hydroxy or 5-chloro 3,5-dimethyl or 4,5-dimethyl 2 (5 H) furanones We studied the Friedel-Crafts reactions of 2-(5H)-furanones. In the presence of sulfuric acid and of an aromatic derivative, 5-hydroxy- or 5-chloro-5-methyl-2-(5H)-furanones with one methyl group either in the 3 position, or in the 4 position generally give the corresponding 5-aryl-2-(5H)-furanones, while with aluminium chloride, it is possible to obtain, when a reaction takes place, isomeric 1H-indenecarboxylic acids. However, in a particular case, an addition to the substrate's double bond is observed. The 3-aryl-5-hydroxy-tetrahydrofuran-2-one obtained is methylated in two ways and gives either a cyclic product, or a linear one. In two cases tautomerism between 1H-1-indenecarboxylic acid and 1H-3-indenecarboxylic has been shown by 1H-NMR.