Synthesis and spectroscopic properties of some merocyanine dyes

The reaction between some 1,1-diarylprop-2-yn-1-ols 3 and cyclohexane-1,3-diones affords merocyanine dyes 7, the valence tautomers of the tetrahydro-2H-[1]benzopyrans. The spectroscopic properties of these dyes are discussed. The isomeric merocyanine dyes 14 and 15 derived from the reaction of 1,1-bis(4-dimethyl-aminophenyl)prop-2-yn-1-ol and 2-tetralone are dehydrogenated to the photochromic 3H-naphtho[2,1-b]pyran 12. This protocol constitutes a new route to the photochromic naphthopyran unit.