SIMPLE SYNTHESIS OF DIMETHYL 4-METHYL-6-PERFLUOROALKYLISOPHTHALATES AND DIMETHYL 5-PERFLUOROALKYLBIPHENYL-2,4-DICARBOXYLATES VIA ACYCLIC PRECURSORS

Reaction of methyl propynoate 2 with acetylmethylenetriphenylphosphora ne 1 a or benzoylmethylenetriphenylphosphorane 1b at 90-degrees-C give s methyl 5-oxo-2-(triphenylphosphoranylidene)hex-3-enoate 4a or methyl benzoyl-2-(triphenylphosphoranylidene)but-3-enoate 4b as the main pro duct, respectively. Phosphoranes 4a or 4b can further react with methy l perfluoroalkynoates 5a and 5b to afford dimethyl l)-4-(triphenylphos phoranylidene)pent-2-enedioates 6a and 6b or dimethyl l)-4-(triphenylp hosphoranylidene)pent-2-enedioates 6c and 6d, respectively. Diemethyl 4-methyl-6-perfluoroalkylisophthalates 7a and 7b or dimethyl 5-perfluo roalkylbiphenyl-2,4-dicarboxylates 7c and 7d were prepared in high yie ld via intramolecular Wittig reaction of phosphoranes 6a/6b or 6c/6d i n benzene or methanol. The structures of compounds 4a, 6a and 7a were confirmed by IR, MS and H-1, F-19 and C-13 NMR spectroscopy and elemen tal analyses. Reaction mechanisms for the formation of compounds 4, 6 and 7 are proposed.