Réactions de friedel-crafts de dérivés aromatiques sur des composés dicarbonylés-1,4éthyléniques-2,3.ii alkylations par quelques hydroxy-5 ou chloro-5 dihydro-2,5 furannones-2. nouvelle méthode de synthèse des acides 1h-indènecarboxyliques-1

With acid catalysts, 3,4-dimethyl-5-hydroxy (or 5-chloro)-2-(5H)furanones substituted at position 5, react with aromatic derivatives to give the corresponding 5-aryl-3,4-dimethyl-2(5H)-furanones in a first step. Some of these 5-aryl furanones are able to isomerize into 1H-indenecarboxylic acids by ring-opening, allylic-type-transposition, and intramolecular alkylation. The nature of the catalyst is important: sulfuric acid leads to the 5-aryl furanones, while aluminium chloride leads in one step, to indenecarboxylic acids. This type of reaction is fairiy general. Reaction mechanisms are proposed and discussed.