Synthesis and biological evaluation of cytotoxic properties of stilbene-based resveratrol analogs

Configuration of stilbene derivatives by 1H NMR and theoretical calculation of chemical shifts

“…As we reported previously [10], the decarboxilation of a-phenylcinnamic acid (1), prepared by the Perkin reaction, gave the cis-stilbene derivative, which was next isomerized to the trans derivative. The analysis, based on of the 3 J HH coupling constant of the olefinic hydrogens, of these decarboxylated products left no doubt on the configuration of the double bond of compound (1).…”

“…The calculated 1 H chemical shifts are shown in Table 2 as an average, according to Boltzmann distribution for the conformers. These calculated chemical shifts are scaled according to linear fit for better comparison with experimental data [10]. The structural feature of the conformers that has a bigger impact on chemical shifts is the rotation around C3-C8 bond, as this conformational change implies in moving certain hydrogens in and out of a shielding zone of a benzene ring.…”

“…Compound 1 was prepared by the reaction of 3,4-dimethoxybenzaldehyde and phenylacetic acid, in the presence of acetic anhydride and triethylamine, as described elsewhere [10]. The 1 H NMR spectrum of compound 1 (see Supplementary material) was run in deuterochloroform at the frequency of 300 MHz.…”

“…With the purpose of contributing to enhance the knowledge of structure-biological activity relationship of these analogs, our research group has synthesized selected molecules and evaluated their cytotoxic potential [10].…”

“…In our route to synthetic analogs of resveratrol [10], we prepared a trisubstituted stilbene derivative, a-phenylcinnamic acid (1), by the Perkin reaction. Although we could infer, a posteriori, the configuration around the double bond of compound 1 from the analysis of the decarboxylation followed by E/Z isomerization products, there is no easy way for a direct stereoisomer assignment of this intermediate.…”