Isoflucypram, the first representative of a new succinate dehydrogenase inhibitor fungicide subclass: Its chemical discovery and unusual binding mode.

Succinate dehydrogenase inhibitors (SDHIs) have played a crucial role in disease control to protect cereals as well as fruit and vegetables for more than a decade. Isoflucypram, the first representative of a newly installed subclass of SDHIs inside the Fungicide Resistance Action Committee (FRAC) family of complex II inhibitors, offers unparalleled long-lasting efficacy against major foliar diseases in cereals. Herein we report the chemical optimization from early discovery towards isoflucypram and the first hypothesis of its altered binding mode in the ubiquinone binding site of succinate dehydrogenase. © 2020 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Et3N-induced demethylation-annulation of 3-alkynyl-4-methoxy-2-pyridones and structurally related compounds in the synthesis of furan-fused heterocycles.

Various 3-iodo-4-methoxypyridin-2-ones and related pyrone and coumarin derivatives have been demonstrated as readily available precursors of 2-substituted furan-fused heterocycles by means of in situ sequential Sonogashira-acetylide coupling, dealkylation, and regioselective furan annulation reactions. A Et3N-induced S(N)2 process has been established that accounts for the dealkylation process.

Flexible strategy for differentially 3,5-disubstituted 4-oxypyridin-2(1H)-ones based on site-selective Pd-catalyzed cross-coupling reactions.

3,5-Dihalogeno-4-methoxy-N-methylpyridin-2(1H)-ones have been shown to undergo single Suzuki coupling reactions in a site-selective fashion. Monoarylations occur at the C-5 position preferentially, thus leaving the remaining C-3 halide free for further functionalization, to finally access differentially 3,5-disubstituted 2-pyridones. This two-step strategy has been applied to the elaboration of the 3-acyl-5-aryl-4-oxy-2-pyridone subunit that is prevalent in numerous bioactive natural products. [reaction: see text].

A synthetic entry to furo[2,3-b]pyridin-4(1H)-ones and related furoquinolinones via iodocyclization.

[reaction: see text] N-Methyl-4-alkoxy-3-alkynylpyridin-2(1H)-ones readily undergo iodine-promoted 5-endo-heteroannulation under mild conditions to 3-iodofuropyridinium triiodide salts in moderate to good yields. The latter may be dealkylated in situ upon exposure to an iodide anion to provide the corresponding 3-iodofuro[2,3-b]pyridin-4(1H)-ones. The same strategy applies to the formation of furo[2,3-b]quinolin-4(9H)-ones.

Efficient syntheses of pterulone, pterulone B and related analogues.

An efficient synthesis of the three halogenated naturally occurring products, pterulone (2), pterulone B (3) and alcohol 5, and of a wide range of related unnatural analogues has been achieved starting from the two readily available 1-benzoxepine sulfonyl-containing intermediates 6a and 6b. The biological activities of pterulone and some of the synthesized analogues were tested against a wide spectrum of phytopathogenic fungi.

Palladium-mediated three-component synthesis of furo[2,3-b]pyridones by one-pot coupling of 3-iodopyridones, alkynes, and organic halides.

[reaction: see text] The one-pot assembly of 4-alkoxy-3-iodo-2-pyridones, terminal alkynes, and organic halides has been achieved by integration of two sequential palladium-mediated cross-coupling reactions--Sonogashira and Wacker-type heteroannulation processes--and subsequent deprotection of the alkoxy group to afford furo[2,3-b]pyridones.