Transketolase (TK) represents a potential target for novel herbicide development. To discover novel TK inhibitors with potency against resistant weeds, 36 thioether compounds containing 1,2,4-triazole Schiff bases were designed and synthesized for herbicidal activity evaluation. The results demonstrated that compounds 5av and 5aw provided excellent weed control with inhibition of over 90% against the tested weeds, even at concentrations as low as 100 mg/L in vitro. In addition, compounds 5av and 5aw exhibited higher postemergence herbicidal activity than all of the positive controls against the tested weeds at 50−90 g [active ingredient (ai)]/ha in a greenhouse, while being safe for crops of maize and wheat at 90 g (ai)/ha. Fluorescent binding experiments of At TK indicated that compounds 5av and 5aw had strong TK inhibitory activity and could tightly bind with the enzyme At TK. Also, molecular docking analyses revealed that the structures of compounds 5av and 5aw were suitable for TK inhibitory activity. Taken together, these results suggested that compounds 5av and 5aw were promising herbicide candidates for weed control in wheat and maize fields targeting TK.
Transketolase
(TK) has been regarded as a new target for the development
of novel herbicides. In this study, a series of 2-thioether-5-(thienyl/pyridyl)-1,3,4-oxadiazoles
were designed and synthesized based on TK as the new target. The preliminary
bioassay results indicated that compounds 4l and 4m displayed the best herbicidal activities against Amaranthus retroflexus (AR) and Digitaria sanguinalis (DS), with
the inhibition exceeding 90% at 100–200 mg/L in vitro. Moreover, they also displayed higher postemergence herbicidal activities
(90% control) against AR and DS than
all of the positive controls at 45–90 g [active ingredient
(ai)]/ha in a greenhouse. Notably, compounds 4l and 4m showed a broad spectrum of weed control at 90 g ai/ha.
More significantly, compound 4l exhibited good crop selectivity
against maize at 90 g ai/ha. Both fluorescent binding experiments
and molecular docking analyses indicated that compounds 4l and 4m exhibited strong TK inhibitory activities with
superior binding affinities than the others. Preliminary mechanism
studies suggested that they might exert their TK inhibitory effects
by occupying the active cavity of At TK and forming
more strong interactions with amino acids in the active site. Taken
together, these results suggested that compound 4l was
a potential herbicide candidate for weed control in maize fields targeting
TK.
The nickel-catalyzed cross-electrophile coupling of 1,2,3-benzotriazin-4(3H)-ones with aryl bromides to generate a diverse array of ortho-arylated benzamide derivatives has been developed. The reaction displayed good functional group tolerance with Zn as the reductant. The key to this transformation is the ring opening of benzotriazinones, which undergo a denitrogenative process to obtain various benzamide derivatives (29 examples, 42−93% yield). The scalability of this transformation was demonstrated.
Organo-silanes,
germanes, and stannanes are considered to be conducive
to the development of cross-coupling reactions because they are stable,
nontoxic, and easy to handle. Using feedstock toluenes, one-pot direct
benzylic C–H silylations, germylations, and stannylations are
developed. Simply combining toluenes, LiN(SiMe3)2/CsCl, and R3MCl (M = Si, Ge, Sn) generates a diverse
array of bench-stable benzyl silanes, germanes, and stannanes (38
examples, 53–90% yields). The syntheses developed here are
easy to access on scale.
The deprotonation of allylbenzene was successfully demonstrated with a catalytic alkali amide base (NaN(SiMe 3 ) 2 ). The deprotonated allyl anion could be trapped by in situ generated N-(trimethylsilyl) aldimines to provide value-added homoallylic amines (39 examples, 68−98% yields) in a one-pot manner with excellent liner selectivity. Compared with the previously reported method for the synthesis of homoallylic amines, this method does not need to use the preinstalled protection groups on the imines, which need to be removed after the reaction to obtain the N−H free homoallylic amine derivatives.
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