Synthesis of methoxybenzoflavones and assignments of their NMR data

Abstract

A phytotoxic root exudate from Acroptilon repens was identified as 7,8-benzoflavone, an inhibitor of cytochrome P450 1A2 and activator of cytochrome P450 3A4. The synthetic 5,6-benzoflavone also is a potent phytotoxin. Six 7,8-benzoflavones and eight 5,6-benzoflavones were synthesized in this study. The NMR data for a few of these compounds have been previously reported; however, the NMR data for most of them have not been reported. For reference purposes, the complete NMR data for the 14 benzoflavones are described.

1H and 13C NMR spectral assignments of 2′‐hydroxychalcones

“…The long‐range coupling time for HMBC was 70 ms. Zero filling of 2 K and the sine‐squared bell window function were applied before Fourier transformation using XWin‐NMR (Bruker) . All NMR data were analyzed using Sparky…”

1H and 13C NMR spectral assignments of novel naphthalenylphenylpyrazolines

“…[13] The same procedures were applied to 2-hydroxynaphthylchalcone (II) to produce the corresponding thioamide compounds (4-7), which were reacted with ethyl bromoacetate to give thiazolone compounds (14)(15)(16)(17)(18). [14] Benzochalcone (III) was reacted with hydrazine to form pyrazoline (IV); then, IV was dissolved in ethanol and treated with an equimolar amount of methoxy-substituted isothiocyanate, and the resulting solution was refluxed.…”

Investigation of 2-hydroxy-4-methoxy-2′,3′-benzochalcone binding to tubulin by using NMR and in silico docking

“…The relaxation delay and the 90 o pulse for the 1 H-NMR experiments were 1 s and 10.2 µs, respectively. Experimental procedures were followed as described previously (Hwang et al, 2012). X-ray crystallographic data were collected on SMART (Bruker AXS Inc.,USA), and then solved and refined using SAINT software (Bruker) (Shin et al, 2013b).…”