BACKGROUND: Pyrisoxazole is a fungicide that has two chiral carbon atoms and four isomers: (3S,5R)-, (3R,5S)-, (3S,5S)-, and (3R,5R)-pyrisoxazole. RESULTS: Pure crystals of four pyrisoxazole isomers were prepared by chiral separation and single-crystal cultivation. Their absolute configurations were established by X-ray single crystal diffraction analysis. Bioassays indicated that compound (3S,5R)-pyrisoxazole showed excellent fungicidal activity with a median effective concentration (EC 50) value of 0.14 ∼g mL −1 and protective activity with an EC 50 value of 13.29 ∼g mL −1. These values are superior to the commercial fungicides boscalid and racemic pyrisoxazole. CONCLUSIONS: The biological activity of racemic pyrisoxazole is due almost exclusively to the isomer (3S,5R)-pyrisoxazole; the other three isomers had very low activity.

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The novel insecticide tetrachlorantraniliprole was synthesized utilizing 2,3,5-trichloropyridine as the starting material by a six-step route in 18% yield. The process of simultaneous oxidation and acyl chlorination was studied by in situ FTIR. The molecular structure of tetrachlorantraniliprole was identified by means of NMR, IR, MS, and X-ray diffraction analyses. The single crystal of tetrachlorantraniliprole was formed from toluene solvent, and exhibited monoclinic P2 1 /n group with crystal parameters of a = 15.3316(16) Å, b = 16.7139(16) Å, c = 19.6687(19) Å, V = 4835.2(8) Å 3 , and Z = 4. Moreover, its density = 1.605 g/m 3 , F(000) = 2328.0, µ = 2.17 mm −1 , and 26933 reflections were measured (2.992° 2θ 51.998°).

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