Synthesis of 2-(9-Fluorenyl)acrylic Acid Derivatives via Intramolecular Friedel-Crafts Reaction of Morita-Baylis-Hillman Adducts of 2-Biphenyl-carboxaldehydes

Treatment of propiolic acid esters or N, N-dimethylpropynamide and various 2-biphenylcarboxaldehydes with tetrabutyl-ammonium iodide/zirconium(IV) chloride, titanium(IV) chloride/dimethyl sulfide, or titanium(IV) bromide/dimethyl sulfide or treatment of methyl acrylate and 2-biphenylcarboxaldehydes with 1,4-diazabicyclo[2.2.2]octane (DABCO) and triethanolamine induce an aldol-type reaction to furnish β-halo-α-(hydroxymethyl)acrylates or α-(hydroxymethyl)acrylates, respectively. These can be used for the preparation of 2-(9 H-fluoren-9-yl)acrylic acid derivatives by intramolecular Friedel-Crafts reaction with sulfuric acid in tetrachloromethane.