Photolysis of hexane solutions of quinolin-2-yl-β-tropolones is accompanied by the photo-induced proton transfer O-H...N → O...H-N followed by the disrotatory electrocyclic rearrangement giving rise to 3-(1H-quinolin-2-ylidene)bicyclo[3.2.0]hept-6-ene-2,4-dione derivatives. The molecular and crystal structure of one of the compounds isolated preparatively, viz., 1,6-di(tert-butyl)-3-(4-chloro-8-methyl-1H-quinolin-2-ylidene)bicyclo[3.2.0]hept-6-ene-2,4-dione, was established by X-ray diffraction. The structures, tautomeric transformations, and the structural dynamics of the resulting compounds were studied by ab initio quantum chemical methods, absorption and fluorescence spectroscopy, and dynamic NMR spectroscopy.