Benzenoid-quinoid tautomerism of azomethines and their structural analogs. 42. Synthesis,structures, and spectral-luminescence properties of 3-hydroxy-2-acetylbenzo[b]thiophene imines

N-Aryl- and N-alkylimines of 3-hydroxy-2-acetylbenzo[b]-thiophene, the most stable isomeric form of which, according to the UV, IR, and ¹H NMR spectra data, is the E-keto enamine structure, were synthesized. Irradiation of the aminovinyl ketones in the region of the long-wave absorption band causes thermally and photochemically reversible EZ isomerization. 2-Aminoethylidene-3-(2H)-benzo[b]thiophenones have low-intensity fluorescence with a normal Stokesian shift, which is absent in solutions of their lithium and sodium salts.See [1] for Communication 41.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 591–595, May, 1989.