Synthesis and biological evaluation of arylpyrazoles as fungicides against phytopathogenic fungi

Abstract

3-phenol-1H-pyrazoles (2), 4-halogeno-3-phenol-1H-pyrazoles (3) and 2-(1-phenol-1H-pyrazol-5-yl)phenols (4) were prepared by the condensation of (E)-3-(dimethylamino)-1-phenylprop-2-en-1-ones and hydrazine hydrate or phenylhydrazine in good yields. They were evaluated against five phytopathogens fungi, namely Cytospora sp., Colletotrichum gloeosporioides, Botrytis cinerea, Alternaria solani and Fusarium solani in vitro. Most of the above-mentioned compounds exhibited activities. For example, 4-chloro-2-(1H-pyrazol-3-yl)phenol (3k) and 4-bromo-3-phenol-1H-pyrazole (3b) showed good and broad-spectrum antifungal properties against Cytospora sp., C. gloeosporioides, Botrytis cinerea, Alternaria solani and F. Solani with [Formula: see text] values ranging from 4.66 to 12.47 [Formula: see text]g/mL. The results showed that pyrazoles with one aryl group at 3-position (2 and 3) exhibited better antibacterial activity than those with two aryl substituents (4). In addition, the existence of an electron-withdrawing group, a substituent on the ortho-position of phenol ring or a halogen atom at the 4-position of the pyrazole enhanced the antifungal activity of pyrazoles 2 and 3. A series of arylpyrazole derivatives was facilely prepared and was evaluated against five phytopathogens fungi including Cytospora sp., Colletotrichum gloeosporioides, Botrytis cinerea, Alternaria solani, and Fusarium solani in vitro. Most of those compounds exhibited remarkable antifungal activities and were superior to the positive control hymexazol.

One‐pot Synthesis of Substituted Pyrazoles from Propargyl Alcohols via Cyclocondensation of in situ‐Generated α‐Iodo Enones/Enals and Hydrazine Hydrate

“…3,4‐Disubstituted pyrazoles were reported to be valuable fungicides against phytopathogenic fungi [15] . Fezolamine [3,4‐diphenyl‐1H‐pyrazole‐1‐propanamines, 80410‐36‐2] is an antidepressant drug, which can be prepared by Michael addition of acrylonitrile to diphenylpyrazole followed by reductive alkylation of the resulting diphenylpyrazolepropionitriles [16] …”

“…3,4-Disubstituted pyrazoles were reported to be valuable fungicides against phytopathogenic fungi. [15] Fezolamine [3,4diphenyl-1H-pyrazole-1-propanamines, 80410-36-2] is an antidepressant drug, which can be prepared by Michael addition of acrylonitrile to diphenylpyrazole followed by reductive alkylation of the resulting diphenylpyrazolepropionitriles. [16] After sequential one-pot synthesis of pyrazoles with substitutions at 1, 3, and 5 position, the synthesis of 3,4disubstituted pyrazoles were further explored.…”

“…Both superacid (TfOH) and middle strong acid (TFA) gave lower yields of 2 a with even longer reaction times compared with Bi(OTf) 3 (entries 10 and 11 vs entry 1). Reactions without catalyst or catalyzed by Lewis acids other than triflate salts, such as FeCl 3 , AlCl 3 , and InCl 3 , gave no rearrangement products (entries [12][13][14][15]. Solvent investigation indicated that dioxane gave the best results among THF, DCM, DCE, benzene, and dioxane (entries 16-19, and entry 1).…”

The Effect of Salt-Tolerant Antagonistic Bacteria CZ-6 on the Rhizosphere Microbial Community of Winter Jujube (Ziziphus jujuba Mill. “Dongzao”) in Saline-Alkali Land

“…The most volatile compound produced by CZ-6 is 2-methylpropylhydrazine. Although no studies have shown that it antagonizes pathogens, its derivatives can be synthesized into pesticides, suggesting the strain's potential use as microbial pesticide [ 56 ]. Recent study has shown that the main VOC produced by the CZ-6 strain, 2-nonanone, can inhibit anthracnose fungus, Candida , and Staphylococcus [ 57 ]; 2-heptanone has also been reported to have strong antifungal activity.…”

Electrochemical Oxidative Cross‐Coupling of Enaminones and Thiophenols to Construct C−S Bonds

“…Enaminones are a kind of important structures, which widely exist in numerous pharmaceuticals and agrochemicals [1] . Moreover, enaminones are often used as important versatile intermediates for the preparation of various heterocycles, [2] such as furans, [2a] pyridines, [2b–d] pyrazoles, [2e,f] thiazines, [2g] quinolones [2h,i] . The functionalization of enaminones is a promising strategy to obtain valuable compounds [3] .…”