Facile preparation of nitroguanidines containing a sulfoximine motif

Recent Progress in Synthetic Applications of Hypervalent Iodine(III) Reagents

Hypervalent iodine(III) compounds have found wide application in modern organic chemistry as environmentally friendly reagents and catalysts. Hypervalent iodine reagents are commonly used in synthetically important halogenations, oxidations, aminations, heterocyclizations, and various oxidative functionalizations of organic substrates. Iodonium salts are important arylating reagents, while iodonium ylides and imides are excellent carbene and nitrene precursors. Various derivatives of benziodoxoles, such as azidobenziodoxoles, trifluoromethylbenziodoxoles, alkynylbenziodoxoles, and alkenylbenziodoxoles have found wide application as group transfer reagents in the presence of transition metal catalysts, under metal-free conditions, or using photocatalysts under photoirradiation conditions. Development of hypervalent iodine catalytic systems and discovery of highly enantioselective reactions using chiral hypervalent iodine compounds represent a particularly important recent achievement in the field of hypervalent iodine chemistry. Chemical transformations promoted by hypervalent iodine in many cases are unique and cannot be performed by using any other common, non-iodine-based reagent. This review covers literature published mainly in the last 7-8 years, between 2016 and 2024.

Design, synthesis, and antifungal activities of novel sulfoximine derivatives for plant protection

BACKGROUND

Fungicides play a significant role in the integrated management of plant pathogens. However, the irrational application of fungicides with similar structures has led to development of cross-resistance, therefore there is a need to seek novel fungicides with new structures.

RESULTS

Twenty-eight novel sulfoximine derivatives incorporating nitroguanidine moieties were designed, synthesized, and evaluated as antifungal agents. The bioassay results indicated that most of the synthesized compounds displayed excellent fungicidal activities against Sclerotinia sclerotiorum, Rhizoctonia solani, Fusarium graminearum, and Pyricularia grisea. Among these, compounds 6c₄ , 6c₅ , and 6c₆ exhibited remarkable fungicidal activities against P. grisea, with EC₅₀ values of 1.28, 1.17, and 1.68 μg mL^-1 , respectively. In addition, compound 6c₂ displayed the most potent activity against S. sclerotiorum (EC₅₀  = 3.64 μg mL^-1 ). Further in vivo fungicidal activity screening against S. sclerotiorum demonstrated that the protective and curative effects of compound 6c₂ were 98.1% and 91.3% at 25 μg mL^-1 , respectively, comparable to that of boscalid (94.4%, 89.6%). The preliminary mechanism study found that the hyphae of S. sclerotiorum treated with compound 6c₂ was abnormal with mycelial collapse and membrane permeability increase. The present findings can help to develop new fungicides for crop protection.

CONCLUSION

Novel sulfoximine derivatives containing nitroguanidine possess potential antifungal activity, and the unique structure may offer an alternative option for fungicide development in the future. © 2022 Society of Chemical Industry.

Design, Synthesis, and Antifungal Activity of Sulfoximine Derivatives Containing Nitroguanidine Moieties

To discover novel pesticide candidates, a series of sulfoximine derivatives were designed and synthesized via the oxidation coupling reaction of sulfides and N -alkyl nitroguanidines. The compounds were evaluated for their antifungal activity against six phytopathogenic fungi. Most of them exhibited a broad spectrum of fungicidal activity in vitro . Compound 8IV-b displayed good fungicidal activity against Sclerotinia sclerotiorum , Rhizoctonia solani , Botrytis cinerea , Fusarium graminearum , and Phytophthora capsici , with EC 50 value of 12.82, 12.50, 17.25, 31.08, and 30.11 mg/L, respectively. In addition, compounds 8III-c and 8IV-e had EC 50 values of 22.23 and 20.67 mg/L against P.capsic , which were significantly better than that of the commercial procymidone (118.15 mg/L). Strikingly, 8IV-d exhibited satisfactory fungicidal activity against B.cinerea, which was comparable to control procymidone in terms of their EC 50 values (7.42 versus 10.83 mg/L), and the bioassays in vivo further confirmed that 8IV-d possessed potent protective effect against B.cinerea at 200 mg/L (72.2%). These present findings will facilitate the design and development of novel potent fungicides.