Synthesis of spiropyrans and merocyanine dyes based on 1-benzothieno[3,2-b]pyrrole

Abstract

A convenient method was developed for the synthesis of photochromic spiropyrans and merocyanine dyes of the 1 benzothieno[3,2 b]pyrroline series based on the conventional condensation of the analog of Fischer's salt, viz., 1,2,3,3 tetramethyl 3H [1]benzothieno [3,2 b]pyrrolium triflate, with aromatic 2 hydroxyaldehydes. Unlike Fischer's salt, benzothieno pyrrolium salts readily undergo the [1,5] sigmatropic rearrangement giving rise to 2H [1]benzo thieno[3,2 b]pyrrole derivatives. The latter compounds were used for the synthesis of the first representatives of the previously unknown spiro compounds and merocyanine dyes. The long wavelength maxima of merocyanines of the 2H benzothienopyrrole series are batho chromically shifted by more than 100 nm with respect to the absorption maxima of the "classical" 3H benzothienopyrrole analogs.

Pyrazolone Derivatives: Synthesis, Anti-inflammatory, Analgesic, Quantitative Structure–Activity Relationship and <i>in Vitro</i> Studies

“…All the reactions were followed by TLC using silica gel F254 plates (Merck), using chloroform: methanol 9 : 1 or chloroform as eluting system and were visualized by UV-lamp. Compounds 1b, 25) and 3a 31) were prepared according to reported methods, while compounds 8a, 36) 8b, 46) 2a, [26][27][28] 2c, 29,30) 2b, [33][34][35] and 3d 32) were prepared according to modified procedures from the reported methods.…”

Synthesis and spectral kinetic study of photoinduced processes of photochromic nitro-substituted indoline and benzothienopyrroline spiropyrans in solutions

“…Absorption spectra of the photoinduced merocyanine form of 1a in toluene (С = 2•10 -3 mol L -1 ) before (1) and after UV irradiation with the mercury xenon lamp through the UFS 8 light filter for 3 (2), 10 (3), and 100 s (Absorption spectra of the photoinduced merocyanine form of ISP 1a in ethanol (С = 2•10 -3 mol L -1 ) before (1) and after successive irradiation with the nonfiltered UV light from the mercury xenon lamp(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18).…”