Structurally Versatile Novel Photochromic Bisarylindenone and Its Acetal: Achievement of Large Cyclization Quantum Yield

Bisarylindenones and an acetal derivative, a novel thermally Irreversible photochromic family based on 6 pi-electrocyclization with three easily modifiable functional groups, have been synthesized. 2,3-Bis(5-methyl-2-phenyl-4-thiazolyl)indenone showed photochromic back-and-forth reactions with two different visible lights. Its ethylene acetal recorded 0.81 as the photocyclization quantum yield in hexane, which is the largest value known to date for 6 pi-electrocyclization In solution.