The widespread presence of secondary amines in agrochemicals, pharmaceuticals, natural products, and small-molecule biological probes has inspired efforts to streamline the synthesis of molecules with this functional group. Herein, we...
α-Amino ketone moieties are present in many pharmacologically active molecules, but their synthesis is challenging. Herein, we report a mild, operationally simple method for direct acylation of α-amino C(sp 3 )−H bonds from carboxylic acids via the merger of carbene and photoredox catalysis. Specifically, cross-coupling reactions between a wide range of carboxylic acids, a class of feedstock chemicals, and readily available N-alkyl anilines by means of single-electron N-heterocyclic carbene catalysis combined with photocatalysis provided access to structurally diverse α-amino ketones. The method features a broad substrate scope and is compatible with a wide array of functional groups. To demonstrate the potential applications of the method, we subjected one of the α-amino ketone products to further transformations.
Synthetic DNA walkers are artificially designed DNA self-assemblies with the capability of performing quasimechanical movement at the micro/nanoscale and have shown extensive promise in biosensing, intracellular imaging, and drug delivery. However, DNA walkers are usually constructed by covalently or coordinately binding DNA strands specifically to hard surfaces, thereby greatly limiting their movement efficiency. Herein, we report an intraparticle and interparticle transferable DNA walker (dynamic micelle-supported DNA walker, DMwalker) constructed by immobilizing walking tracks and walking arms onto the corona of DNA micelles according to the principle of Watson−Crick base pairing. The DNAzyme-powered walking arm can drive the intraparticle and interparticle movements of the DM-walker due to the fact that the dynamic structure of the DNA micelle helps overcome the spatial barrier between the arms and tracks in the system, resulting in high walking efficiency. Moreover, the whole DM-walker can be constructed by self-assembly, getting rid of the tedious process and low efficiency of fixing DNA strands on hard surfaces. Taking miRNA-10b as a model target, the DM-walker demonstrates high walking efficiency (reaction duration of 20 min) and high sensitivity (LOD of 87 pM). The proposed DM-walker provides an avenue to develop novel DNA walkers on dynamic interfaces and holds great potential in clinical diagnosis.
BACKGROUND
Insect pests seriously decrease the yield and quality of agricultural crops. Resistance to commonly used insecticides is increasingly undermining their effectiveness, and therefore the development of agents with novel modes of action is desirable. Isoxazolines are a new class of insecticides that act on γ‐aminobutyric acid (GABA) gated chloride channels. In this work, we used the highly active 4‐triazolyphenyl isoxazoline DP‐9 as a parent structure to design and synthesize a series of quaternary ammonium salt (QAS) derivatives, and we systematically evaluated their insecticidal and antifungal activities.
RESULTS
Many of the synthesized QASs exhibit insecticidal activities equivalent to or higher than that of DP‐9. In particular, compounds I‐31 (93%, 0.00005 mg/L) and I‐34 (80%, 0.00001 mg/L) showed insecticidal activities against diamondback moth larvae that were 2–10 times higher than those of fluralaner (70%, 0.0001 mg/L) and DP‐9 (80%, 0.0001 mg/L), in addition to showing excellent activities against oriental armyworm, fall armyworm, cotton bollworm, corn borer, and mosquito larvae. Furthermore, all of the synthesized compounds also showed broad‐spectrum fungicidal activities.
CONCLUSION
The insecticidal activities of QAS derivatives of DP‐9 were the same as or better than the activity of DP‐9. Compounds I‐31 and I‐34 showed better insecticidal activities against diamondback moth larvae than fluralaner and DP‐9, and thus are promising new candidates for insecticide research.
Herein, we report a mild, operationally simple, multicatalytic method for the synthesis of β,γ-unsaturated ketones via allylic acylation of alkenes. Specifically, the method combines N‑heterocyclic carbene catalysis, hydrogen atom transfer catalysis, and photoredox catalysis for cross-coupling reactions between a wide range of feedstock carboxylic acids and readily available olefins to afford structurally diverse β,γ-unsaturated ketones without olefin transposition. The method could be used to install acyl groups on highly functionalized natural-product-derived compounds with no need for substrate pre-activation, and C–H functionalization proceed with excellent site selectivity. To demonstrate the potential applications of the method, we convert a representative coupling product into various useful olefin synthons.
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