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

Abstract 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.