Substituted 2‐(ortho‐hydroxyaryl)cyclopenta[b]pyridines: Synthesis and Fluorescent Properties under Neutral, Acidic Medium and Solid State

Abstract

New derivatives of substituted 2‐(ortho‐hydroxyaryl)cyclopenta[b]pyridines were synthesized by pseudo‐five component reaction of cyclopentanone, two molecules of aromatic aldehyde, Kröhnke salt of ortho‐hydroxy substituted aromatic ketone and ammonium acetate. On the basis of the counter four‐component synthesis, the path of this transformation has been established. The fluorescent properties of the obtained structures are considered in chloroform under neutral, acidic conditions (TFA added) and in the solid state.

DBU-catalyzed synthesis of unsymmetrical cross-conjugated 2-arylidene-5-((dimethylamino)methylene)cyclopentanones

“…(E)-2-(3,4,5-trimethoxybenzylidene)cyclopentan-1-one (1i) Yellow solid, yield 66%; m.p.= 133.9-135.8 °C (lit. m.p.=134-136°C) 2 . 1 H NMR (CDCl3, 400 MHz, δ, ppm, J/Hz): 7.29 (t, J = 2.5 Hz, 1H), 6.76 (s, 2H), 3.87 (s, 9H), 2.98 (td, J = 7.4 Hz, 2.5 Hz, 2H), 2.39 (t, J = 7.9 Hz, 2H), 2.03 (p, J = 8.1 Hz, 2H).…”

“…m.p. = 153-155) 2 . 1 H NMR (CDCl3, 400 MHz, δ, ppm, J/Hz): 7.75 (t, J = 2.7 Hz, 1H), 7.04 (s, 1H), 6.50 (s, 1H), 3.90 (s, 3H), 3.83 (m, 6H), 2.91 (td, J = 7.2, 2.7 Hz, 2H), 2.35 (t, J = 7.7 Hz, 2H), 2.00 (p, J = 8.0 Hz, 2H).…”

“…Solvents were chloroform with a sample concentration of 2x10 -6 mol/dm 3 . 2arylidenecyclopentanone (1a-c,e,g,i-l) was prepared by known methods 1,2 . All reactions were performed in air with constant magnetic stirring.…”

Multicomponent synthesis of chromophores – The one-pot approach to functional π-systems

“…Frontiers in Chemistry frontiersin.org 25 (ortho-hydroxyaryl)cyclopenta[b]pyridines 79 and 80 are synthesized with yields ranging from 19% to 87% (Supplementary Material S27) (Batalin et al, 2021). For the aromatic aldehyde either benzaldehyde or up to 3 methoxy groups with various substitution patterns on the aromatic ring were furnished, which influenced the yields and the amount of pyridium salt added.…”

New type of cross-conjugated cyclopentanones as of ketocyanine dye - 2-arylidene-5-((dimethylamino)methylene)cyclopentanones: synthesis and photophysical properties

“…This work is a continuation of research on the synthesis and study of the photophysical properties of systems based on cyclopentanone [21][22][23][24] and is aimed at the synthesis of a series of new ketocyanines of the 2-arylidene-5-((dimethylamino)methylene)cyclopentanones and the study of their photophysical properties depending on the nature substituents and the polarity of the medium.…”