One-Step Synthesis and Stealth Photochromism of Arylbutadienes.

The synthesis of thermally irreversible photochromic arylbutadienes has been demonstrated with a one-step reaction using commercially available ketones by McMurry cross-coupling. Although ( Z)-5-(1-([1,1'-bi(cyclopentylidene)]-2-ylidene)ethyl)-4-methyl-2-phenylthiazole, a 1-(4-methyl-2-phenyl-5-thiazolyl)butadiene, showed poor photochromism, ( Z)-5-(1-([1,1'-bi(cyclopentylidene)]-2-ylidene)ethyl)-2,4-dimethylthiazole, a 1-(2,4-dimethyl-5-thiazolyl)butadiene, showed stealth photochromic transformations by 313 and 366 nm light irradiation between the moderate conversion ratios of the open and closed forms.