Structure, tautomerism, and features of 1-(5-acetyl-2,4-dihydroxyphenyl)-3-(furan-2-yl)prop-2-en-1-one (FC) and 1,1′-(4,6-dihydroxybenzene-1,3-diyl)bis[3-(furan-2-yl)prop-2-en-1-one] (FDC)

Abstract

Quantum chemistry studies of various tautomeric/rotameric forms of the furanyl analogues of acetyl dihydroxychalcone (FC) and dihydroxydichalcone (FDC) have shown that the thermodynamically most stable molecules are planar. In the crystalline solid phase, both molecules are more (FDC) or less (FC) non-planar. Two relatively strong intramolecular H-bonds, whose existence is evidenced by X-ray, computational, and spectral investigations, stabilize the planar geometry and influence the features of the lowest energy tautomers/rotamers of both compounds. Extending to the visible region, the electronic absorption of FC and FDC is accompanied by an intramolecular electron density shift, a property that could have analytical implications. Keywords Chalcone and dichalcone furanyl analogues Á Crystal and computed structures Á Tautomerism Á Intra-and intermolecular interactions Á Spectral features Electronic supplementary material The online version of this article (

Single and double intramolecular proton transfers in the electronically excited state of flavone derivatives

“…Reagents of relevant grade for syntheses and spectroscopic investigations were purchased from Sigma-Aldrich. Identity of the investigated compounds was conrmed with H 1 -NMR, C 13 -NMR and MALDI TOF MS, their purity was controlled with TLC and elemental analysis. NMR spectra were recorded on 500 MHz 1 H (125 MHz 13 C) or 200 MHz 1 H spectrometers with trimethylsilane as reference.…”

“…In an attempt to obtain a derivative of 3,7-dihydroxyavone with a carbonyl fragment in position 6 we rstly made an attempt to synthesize 6-acetyl-3,7-dihydroxy-2-phenyl-4H-chromen-4-one starting from the commercially available 1,1 0 -(4,6-dihydroxy-1,3-phenylene)bisethanone. However, reaction of the latter with equimolar quantity of benzaldehyde and other aldehydes in alkalinic media led to a mixture of mono-and dichalcone derivatives, 13 which were difficult to separate. In order to eliminate formation of the undesired dichalcone product, 1,1 0 -(4,6dihydroxy-1,3-phenylene)bisethanone derivatives were designed with substituent(s) in one of the a positions (5, Scheme 1).…”

“…2b: White powder (67%), 1 H NMR (500 MHz, DMSO-d 6 , d): 7.05 (s, 1H), 7.09 (d, 1H, J ¼ 8.9 Hz), 7.55-7.60 (m, 3H), 8.14 (d, 1H, J ¼ 8.9 Hz), 8.16-8.21 (m, 2H); 10.60 (s, 1H), 12.16 (broad s, 1H). 13 3,7-Dihydroxy-4-oxo-2-phenyl-4H-chromene-8-carbaldehyde (2a). The compound was prepared from 7-hydroxy-3-methoxy-2phenyl-4H-chromen-4-one 12 following the procedure described for 1a.…”

“…Pale yellow powder (84%), 1 H NMR (500 MHz, DMSO-d 6 , d): 7.09 (d, 1H, J ¼ 8.9 Hz), 7.50 (t, 1H, J ¼ 6.9 Hz), 7.58 (t, 2H, J ¼ 7.5 Hz), 8.24 (d, 1H, J ¼ 8.9 Hz), 8.37 (d, 2H, J ¼ 7.5 Hz), 9.77 (s, 1H), 10.60 (s, 1H), 12.23 (broad s, 1H). 13…”

Crystal structure and Hirshfeld surface analysis of (E)-1-(3,5-dichloro-2-hydroxyphenyl)-3-(5-methylfuran-2-yl)prop-2-en-1-one

“…A search of the Cambridge Structural Database (CSD, Version 5.39, last update August 2018; Groom et al, 2016) for 3-(furan-2-yl)-1-(2-hydroxyphenyl)prop-2-en-1-ones gave six hits. These involve only four compounds, namely: 3-(furan-2yl)-1-(2-hydroxyphenyl)prop-2-en-1-one itself (BOGVID; Kong & Liu, 2008); 1-(5-bromo-2-hydroxyphenyl)-3-(2-furyl)prop-2-en-1-one, for which variable pressure measurements were carried out (KUDMON, KUDMON01, KUDMON02; Bakowicz et al, 2015); 1,1 0 -(4,6-dihydroxy-1,3-phenylene)bis[3-(2-furyl)prop-2-en-1-one] (POHZUJ; Wera et al, 2014); and 1-(5-acetyl-2,4-dihydroxyphenyl)-3-(2-furyl)prop-2-en-1-one (POJBAT; Wera et al, 2014). As in the title compound there are intramolecular O-HÁ Á ÁO hydrogen bonds present forming S(6) ring motifs.…”