Synthesis of Novel Thermally Reversible Photochromic Spiro[adamantane-2,7(6H)-benzothiophene]

A new thermally reversible photochromic compound, 4ʹ,5ʹ-hexafluoropropano-6ʹ-phenylspiro[adamantane-2,7ʹ(6ʹH)-benzothiophene], derived from UV-irradiation of 2-(1-adamantylidene-1-phenylmethyl)-3,3,4,4,5,5-hexafluoro-1-(3-thienyl)cyclopentene via the photochemical 6(pi)-electrocyclization followed by the thermal 1,5-hydrogen migration, was synthesized and its photochemical and thermal properties were examined. The structurally more simplified 3,3,4,4,5,5-hexafluoro-2-(2methyl-1-phenyl-1-propenyl)-1-(3-thienyl)cyclopentene did not yield the thermally reversible photochromic compound upon UV irradiation.