Regioselective synthesis of heterocyclic N-sulfonyl amidines from heteroaromatic thioamides and sulfonyl azides

N-Sulfonyl amidines bearing 1,2,3-triazole, isoxazole, thiazole and pyridine substituents were successfully prepared for the first time by reactions of primary, secondary and tertiary heterocyclic thioamides with alkyl- and arylsulfonyl azides. For each type of thioamides a reliable procedure to prepare N-sulfonyl amidines in good yields was found. Reactions of 1-aryl-1,2,3-triazole-4-carbothioamides with azides were shown to be accompanied with a Dimroth rearrangement to form 1-unsubstituted 5-arylamino-1,2,3-triazole-4-N-sulfonylcarbimidamides. 2,5-Dithiocarbamoylpyridine reacts with sulfonyl azides to form a pyridine bearing two sulfonyl amidine groups.

Efficient construction of bioactive trans-5A5B6C spirolactones via bicyclo[4.3.0] α-hydroxy ketones

The intricate 5_A5_B6_C-ring fusion topologies of tricyclic spiranoid β-hydroxybutyrolactones with environmentally benign characteristics and moderate biological activities were synthesized through lactonization of the key intermediate trans-α-hydroxyindenones with malonates by an efficient and convenient short synthetic procedure.

Design, synthesis and fungicidal activity of isothiazole–thiazole derivatives

3,4-Dichloroisothiazoles can induce systemic acquired resistance (SAR) to enhance plant resistance against a subsequent pathogen attack, and oxathiapiprolin exhibits excellent anti-fungal activity against oomycetes targeting at the oxysterol-binding protein. To discover novel chemicals with systemic acquired resistance and fungicidal activity, 21 novel isothiazole–thiazole derivatives were designed, synthesized and characterized according to the active compound derivatization method. Compound 6u, with EC₅₀ values of 0.046 mg L⁻¹ and 0.20 mg L⁻¹ against Pseudoperonospora cubensis (Berk. et Curt.) Rostov and Phytophthora infestans in vivo, might act at the same target as oxysterol binding protein (PcORP1) of oxathiapiprolin; this result was validated by cross-resistance and molecular docking studies. The expression of the systemic acquired resistance gene pr1 was significantly up-regulated after treating with compound 6u for 24 h (43-fold) and 48 h (122-fold). These results can help the development of isothiazole–thiazole-based novel fungicides.

Compound 6u exhibits ultrahigh fungicidal activity by acting at its potent target PcORP1 and induces systemic acquired resistance by activating the salicylic acid pathway.