关键词: 电催化, 芳基乙烯, 硫羟基化, β-羟基硫醚, 抗菌活性

As the core skeleton structure of many drugs and natural products, β-hydroxysulfides exhibit a variety of biological activities, including anti-fungal, anti-tumor, anti-inflammatory, and anti-HIV properties. They are also used as synthetic building blocks. Complementary catalytic methods that facilitate the efficient synthesis of structurally diverse β-hydroxysulfides are highly sought after. Herein, a mild and efficient electricity-driven strategy has been developed for the synthesis of β-hydroxysulfides from aryl alkenes and trimethylsilyl sulfides in an undivided cell with Mg anode and graphite cathode, while exhibiting mild conditions, high atom-economy, and excellent functional group tolerance. The reaction avoids the use of transition-metal catalysts, peroxide reagents, and malodorous thiols. A representative procedure is described as follows. A mixture of styrene (28.3 mg, 0.2 mmol), (phenylthio)trimethylsilane (58.9 mg, 0.3 mmol), and ⁿBu₄NBF₄ (65.8 mg, 0.2 mmol) in acetonitrile (8 mL) and acetic acid (1 mL) was added to a three-necked flask (10 mL). The electrolysis was performed in an undivided cell equipped with a Mg rod anode (Ø = 6 mm) and a graphite rod cathode (Ø = 6 mm) under a constant current of 16 mA (~20.4 mA/cm²) at room temperature for 4 h. After completion, the mixture was extracted with ethyl acetate. The combined organic layers were washed with brine, dried over anhydrous Na₂SO₄, filtered, and concentrated. The crude product was purified by silica gel column chromatography to afford the target compound. Based on the synthesis, the antifungal activities of the target compounds, β-hydroxysulfides, was tested using the mycelial growth rate method in vitro. With the commercial fungicide Azoxystrobin (Azo) as the positive control, the antifungal activities of the target compounds against two plant pathogenic fungi, Rhizoctonia solani (R.s.) and Botrytis cinerea (B.c.), were determined at a concentration of 100 μg/mL. Notably, some compounds showed higher inhibition rates against the tested fungi than the control agent Azoxystrobin. Among them, at a concentration of 100 μg/mL, compound (3ae) exhibited inhibition rates of 90% and 97% against R.s. and B.c., respectively. which were superior to those of the control agent Azoxystrobin (72% and 74%, respectively). Finally, a preliminary exploration was conducted on the relationship between the antifungal activities of the target compounds and their molecular structures, providing valuable insights for the future development of more efficient agricultural antifungal agents.

Key words: electrochemical catalysis, aryl alkenes, thiohydroxylation, β-hydroxysulfide, antifungal activity