The synthesis and the photochromic properties of new phenanthropyran derivative containing styryl substituent are described. The compound 8 showed two-step two-photon photochromism to produce a thermally stable cyclopentaannulated compound 10 through a thermally unstable open keto form intermediate 9. © 2004 Elsevier B.V. All rights reserved.
Kim, N., Yi, K. Y., Yoo, S. E., Kim, G., & Park, S. K. (2005). Synthesis and photochromic properties of phenanthropyran derivative substituted with styryl group. Journal of Photochemistry and Photobiology A: Chemistry, 170(2), 169–175. https://doi.org/10.1016/j.jphotochem.2004.08.007