Synthesis and Anti‐Oomycete Activity of Sulfonate Derivatives of Fenjuntong

Abstract

In order to discover highly active fungicides, sixteen novel sulfonate derivatives of Fenjuntong were synthesized by structural modification of 2′‐hydroxybutyrophenone, and their anti‐oomycete activity against Phytophthora capsici Leonian was determined in this study. Among all tested compounds, compound 3b displayed more significant anti‐oomycete activity than the precursor Fenjuntong against P. capsici, and the EC50 values of 3b and Fenjuntong were 84.50 and 517.25 mg/L, respectively. By comparing the anti‐oomycete activity of compounds 3a–p, I‐a–p, and II‐a–p, the following conclusions were drawn: (1) Hydroxy group is well tolerated, and sulfonylation of hydroxy group enhances its anti‐oomycete activity. (2) The proper length of the ketone carbonyl chain is very important for their anti‐oomycete activity. (3) The presence of a site methoxy group in the structural skeleton is closely related to the anti‐oomycete activity. These important results will pave the way for further modification of Fenjuntong to develop potential new fungicides.

Synthesis of Hinokitiol Sulfonate Derivatives and Their Anti‐Oomycete and Nematicidal Activities

“…Hinokitiol (1) reacted with RSO 2 Cl (2a -p) to prepare a series of hinokitiol ester derivatives (3a -p) in suitable yields. [23][24][25][26][27][28][29][30][31] The structures of all title compounds were well confirmed by 1 H-NMR, 13 C-NMR, HRMS, and m.p., and the data of compounds 3a-p can be found in the Supporting Information. Interestingly, the two methyl groups on the isopropyl group at position C-4 in the structure of hinokitiol are not coupled with the hydrogen atom on the tertiary carbon atom, and both methyl groups are singlets.…”

“…The synthetic route of the target compounds is depicted in Scheme 1. Hinokitiol ( 1 ) reacted with RSO 2 Cl ( 2a – p ) to prepare a series of hinokitiol ester derivatives ( 3a – p ) in suitable yields [23–31] . The structures of all title compounds were well confirmed by 1 H‐NMR, 13 C‐NMR, HRMS, and m.p., and the data of compounds 3a – p can be found in the Supporting Information .…”

“…brine (20 mL), dried over anhydrous Na 2 SO 4 , concentrated under reduced pressure, and purified by CC to obtain hinokitiol ester derivatives (3a -p) in 17 -54 % yields. [23][24][25][26][27][28][29][30][31][32][33] The data of title compounds 3a-p can be found in the Supporting Information.…”

“…Our previous studies showed that sulfonate derivatives of 3-methoxyphenol (I-1, Figure 1), 2-hydroxyacetophenone (I-2, Figure 1), paeonol (I-3, Figure 1), Fenjuntong (I-4, Figure 1), α/βnaphthol (II-1/II-2, Figure 1), maltol/ethyl maltol (III-1/ III-2, Figure 1), eugenol/dihydroeugenol (IV-1/IV-2, Figure 1), and carvacrol/thymol (V-1/V-2, Figure 1) have clear anti-oomycete activity against P. capsici. [23][24][25][26][27][28][29][30][31] In addition, componds I-3 and III-1 have nematicidal activity against Heterodera glycines Ichinohe and Bursaphelenchus xylophilus (Steiner et Buhrer), respectively. [25,29] Overall, to the best of our knowledge, study on the synthesis of novel 2-sulfonyloxyhinokitiol derivatives (3a -p, Figure 1) as anti-oomycete and nematicidal agents against P. capsici has not yet been reported.…”

“…Previous studies have shown that hinokitiol has a wide range of pharmacological effects and biological activities, [16–22] such as antibacterial activity, [18] antifungal activity, [19] neuroprotective activity, [16] anti‐inflammatory activity, [20] anti‐plasmodial activity, [21] antitumor activity, [22] etc. Our previous studies showed that sulfonate derivatives of 3‐methoxyphenol ( I‐1 , Figure 1), 2‐hydroxyacetophenone ( I‐2 , Figure 1), paeonol ( I‐3 , Figure 1), Fenjuntong ( I‐4 , Figure 1), α/β‐naphthol ( II‐1/II‐2 , Figure 1), maltol/ethyl maltol ( III‐1/III‐2 , Figure 1), eugenol/dihydroeugenol ( IV‐1/IV‐2 , Figure 1), and carvacrol/thymol ( V‐1/V‐2 , Figure 1) have clear anti‐oomycete activity against P. capsici [23–31] . In addition, componds I‐3 and III‐1 have nematicidal activity against Heterodera glycines Ichinohe and Bursaphelenchus xylophilus (Steiner et Buhrer), respectively [25,29] .…”