Synthesis and Anti‐Oomycete Activity of 1‐Sulfonyloxy/Acyloxydihydroeugenol Derivatives

Abstract

Endeavor to discover biorational natural products‐based fungicides, two series (26) of novel 1‐sulfonyloxy/acyloxydihydroeugenol derivatives (3a–p and 5a–j) were prepared and assessed for their fungicidal activity against P. capsici Leonian, in vitro. Results of fungicidal activity revealed that, among all compounds, especially compounds 3a, 5c, and 5e displayed the most potent anti‐oomycete activity against P. capsici with EC50 values of 69.33, 68.81, and 67.77 mg/L, respectively. Overall, the anti‐oomycete activities of 1‐acyloxydihydroeugenol derivatives (5a–j) were higher than that of 1‐sulfonyloxydihydroeugenol derivatives (3a–p). It is proved that the introduction of the acyl group at hydroxy position of dihydroeugenol is more beneficial to improve its anti‐oomycete activity than that of the sulfonyl group. These preliminary results will pave the way for further modification of dihydroeugenol in the development of potential new fungicides.

Synthesis and Anti‐Oomycete Activity of Sulfonate Derivatives of Fenjuntong

“…As depicted in Scheme 1, 1 reacted with R 1 SO 2 Cl to afford Fenjuntong sulfonic ester derivatives ( 3a – p ) in suitable yields [20–25] . The structures of all target compounds were confirmed by 1 H‐NMR, 13 C‐NMR, HR‐MS, and m.p., and the data of compounds 3a – p can be found in the Supporting Information .…”

“…The EC 50 values of 3b and Fenjuntong were 84.50 and 517.25 mg/L, respectively. [20][21][22][23][24][25] The data of target compounds 3a-p can be found in the Supporting Information.…”

“…Subsequently, the organic phase was combined, washed by saturated aq. brine (30 mL), dried over anhydrous Na 2 SO 4 , concentrated under reduced pressure, and purified by silica gel CC to obtain 1‐sulfonyloxydihydroeugenol derivatives in 24–54 % yields [20–25] . The data of target compounds 3a – p can be found in the Supporting Information .…”

“…Mean colony diameter (minus the diameter of the plug) was measured for each treatment and expressed as a percentage of growth inhibition. The median effective concentration (EC 50 ) of 3a – p , and zoxamide for P. capsici isolate was calculated by linear regression of relative percentage of growth inhibition against log transformed samples concentration [20–25] …”

“…Our previous studies showed that sulfonate derivatives of 2-hydroxyacetophenone (I-a-p, Figure 1), paeonol (II-a-p, Figure 1), α/β-naphthol (III/IV, Figure 1), maltol (V, Figure 1), eugenol/dihydroeugenol (VI/VII, Figure 1), and carvacrol/thymol (VIII/IX, Figure 1) have obvious anti-oomycete activity against P. capsici. [20][21][22][23][24][25] P. capsici is a typical oomycete that cause serious diseases in various plants worldwide and threaten the production of agriculture every year. [2,26,27] Fenjuntong is a non-food bioactive product that has a wide range of biological activities.…”