Synthesis and Fungicidal Activity of Hydrated Geranylated Phenols against Botrytis cinerea

Abstract

Botrytis cinerea is a ubiquitous fungus that affects hundreds of plants, resulting in economic losses to the horticulture and fruit industry. The search for new antifungal agents is a matter of current interest. Thus, in this work a series of geranylated phenols in which the side alkyl chain has been hydrated have been synthesized, and their activity against B. cinerea has been evaluated. The coupling of phenol and geraniol has been accomplished under microwave irradiation obtaining the highest reaction yields in the shortest reaction times. Hydration of the side chain was carried out in dioxane with p-toluenesulfonic acid polymer-bound as the catalyst. All synthesized compounds were tested against B. cinerea using the growth inhibition assay and EC50 values were determined. The results show that activity depends on the number and nature of functional groups in the phenol ring and hydration degree of the geranyl chain. The most active compound is 1,4-dihydroquinone with one hydroxyl group attached at the end of the alkyl chain. Results from a molecular docking study suggest that hydroxyl groups in the phenol ring and alkyl chain are important in the binding of compounds to the active site, and that the experimental antifungal activity correlates with the number of H-bond that can be formed in the binding site.

Sulphonic Acid Functionalized Ionic Liquids as an Efficient Catalyst for the Synthesis of Digeranyl Ethers and Geranyl Phenols

“…However, in our case, these syntheses were achieved with only 1 mmol % IL-1 with excellent yields in comparatively shorter reaction time. Very low isolated yields, high reaction time, dry reaction conditions, low yields, and high temperature conditions reported for the synthesis of geranyl phenol using BF 3 • Et 2 O, BF 3 • Et 2 O/AgNO 3 , BF 3 • Et 2 O/Microwave reactor, [24][25][26][27][28][29][30][31][32] p-TsOH. [33] Although appropriate comparison can be made with acidic alumina, however, the conversion takes place at considerably higher reaction time (24 h).…”

“…[24][25][26][27][28][29] Alternatively, BF 3 • Et 2 O/AgNO 3 has been used as catalyst in acetonitrile that leads to formation of hydrated geranyl phenols. [30,31] Similarly, microwave reactor assisted synthesis of geranyl phenols in presence of BF 3 • Et 2 O was achieved in 10 min [32] while another route is explored with p-TsOH at 20 °C in CH 2 Cl 2. [33] Recently, heterogeneous catalyst like acidic alumina are also used for the geranylation of activated phenols that leads to formation of cannabinoid compounds.…”