Benzoid-Quinoid Tautomerism of Schiff Bases and Their Structural Analogs: LI. Photoacylotropic Enaminoketones with a Fluorophoric Migrant

The acylation of ortho-substituted (R = OH, OMe, NHTs) 2-arylaminomethylene-2,3-dihydro- benzob]thiophen-3-ones with (4-methyl-2-oxobenzob]pyran-7-yloxy)acetyl chloride results in formation of the corresponding N-acyl enaminoketones. The same reaction with 2-(2-hydroxyphenylaminomethylene)-2,3- dihydrobenzob]thiophen-3-one gives rise to a tautomeric mixture of acyloxyphenyl and N-acyl enaminoketone isomers. Irradiation at a wavelength corresponding to the absorption region of the N-acyl enaminoketone isomer leads to NO acyl group transfer to afford O-acylated isomer. The complex formation ability of all tautomeric forms with respect to Zn²⁺ and Ni²⁺ cations and their fluorescence properties were studied.