Effective synthesis of fluorine-containing phenanthrene bearing hydroxyl group using Mallory reaction and its application for fluorinated polyesters

Mallory reaction of 1,2-bis(4-hydroxyphenyl)-3,3,4,4,5,5-hexafluorocyclopentene under light irradiation (lambda = 356 nm) in the presence of iodine as an oxidant proceeded to give fluorine-containing phenanthrene bearing hydroxyl groups, 6,9-bis(4-hydroxyphenyl)-1,1,2,2,3,3-hexafluoro-2,3-dihydro-1H-cyclopenta[l]phenanthrene. Polycondensation of the prepared fluorine-containing phenanthrene with various acid dichlorides afforded the phenanthrene-type polyesters. For comparison, diarylethene-type polyesters were also prepared analogously. Diarylethene-type polyesters consisting m-phenylene unit showed good solubility in typical organic solvents such as CHCI3. Tetramethylene-linked diarylethene-type polyesters with M-n = 4100 (M-n = number average molecular weight) was isolated as oil. Other diarylethene-type and all phenanthrene-type polyesters were insoluble in organic solvents. The phenanthrene-type polyesters had high thermal stability revealed by TGA analysis.