Cobalt-Catalyzed Enantioselective Reductive Arylation, Heteroarylation, and Alkenylation of Michael Acceptors via an Elementary Mechanism of 1,4-Addition

Cobalt complexes with chiral quinox ligands effectively promote the enantioselective conjugate addition of enones using aryl, heteroaryl, and alkenyl halides and sulfonates. Additionally, a cobalt complex with a strongly donating diphosphine, BenzP*, successfully catalyzes the asymmetric reductive arylation and alkenylation of α,β-unsaturated amides. Both catalytic systems show broad scopes and tolerance of sensitive functional groups. Both reactions can be scaled up with low loadings of cobalt catalysts. Experimental results and density functional theory (DFT) calculations suggest a new mechanism of elementary 1,4-addition of aryl cobalt(I) complexes.

Quinoline Derivatives in Discovery and Development of Pesticides

Finding highly active molecular scaffold structures is always the key research content of new pesticide discovery. In the research and development of new pesticides, the discovery of new agricultural molecular scaffold structures and new targets still faces great challenges. In recent years, quinoline derivatives have developed rapidly in the discovery of new agriculturally active molecules, especially in the discovery of fungicides. The unique quinoline scaffold has many advantages in the discovery of new pesticides and can provide innovative and feasible solutions for the discovery of new pesticides. Therefore, we reviewed the use of quinoline derivatives and their analogues as molecular scaffolds in the discovery of new pesticides since 2000. We systematically summarized the agricultural biological activity of quinoline compounds and discussed the structure-activity relationship (SAR), physiological and biochemical properties, and mechanism of action of the active compounds, hoping to provide ideas and inspiration for the discovery of new pesticides.

Bioactivity-Guided Subtraction of MIQOX for Easily Available Isoquinoline Hydrazides as Novel Antifungal Candidates

The discovery of novel and easily available leads provides a convincing solution to agrochemical innovation. A bioassay-guided scaffold subtraction of the previous "Chem-Bio Model" isoquinoline-3-oxazoline MIQOX was conducted for identifying the easily available isoquinoline-3-hydrazide as a novel antifungal scaffold. The special and practical potential of this model was demonstrated by a phenotypic antifungal bioassay, molecular docking, and cross-resistance evaluation. A panel of antifungal leads (LW2, LW3, and LW11) was acquired, showing much better antifungal performance than the positive controls. Specifically, compound LW3 exhibited a broad antifungal spectrum holding EC₅₀ values as low as 0.54, 0.09, 1.52, and 2.65 mg/L against B. cinerea, R. solani, S. sclerotiorum , and F. graminearum, respectively. It demonstrated a curative efficacy better than that of boscalid in controlling the plant disease caused by B. cinerea. The candidate LW3 did not show cross-resistance to the extensively used succinate dehydrogenase inhibitor (SDHI) fungicides and can efficiently inhibit resistant B. cinerea strains. The molecular docking of compound LW3 is quite different from that of the positive controls boscalid and fluopyram. This progress highlights the practicality of isoquinoline hydrazide as a novel model in fungicide innovation.

Nickel-Catalyzed Enantioselective Reductive Arylation and Heteroarylation of Aldimines via an Elementary 1,4-Addition

Nickel catalysts of chiral pyrox ligands promoted enantioselective reductive arylation and heteroarylation of aldimines, using directly (hetero)aryl halides and sulfonates. The catalytic arylation can also be conducted with crude aldimines generated from condensation of aldehydes and azaaryl amines. Mechanistically, density functional theory (DFT) calculations and experiments pointed to an elementary step of 1,4-addition of aryl nickel(I) complexes to N-azaaryl aldimines.

A triple cascade approach towards the diastereoselective synthesis of spiro trans-decalinol scaffolds

A [2+2+2] annulation reaction between cyclohexanone, β-nitrostyrene and 2-arylidene-1,3-indanedione afforded multisubstituted spiro trans-decalinol derivatives in high chemical yields (up to 75%) and excellent diastereoselectivity (up to >20 : 1) at room temperature. This one-pot three-component system follows a triple cascade sequence via the Michael/nitro-Michael/Aldol process, resulting in the formation of three C-C bonds, five contiguous stereocenters as well as a spiro quaternary carbon center.

Asymmetric Synthesis of Sakuranetin-Relevant Flavanones for the Identification of New Chiral Antifungal Leads

Discovery and efficient synthesis of new promising leads have a central role in agrochemical science. Reported herein is the sakuranetin-directed synergistic exploration of an asymmetric synthesis and an antifungal evaluation of chiral flavanones. A new palladium catalytic system with CarOx-type ligands was successfully identified for the highly enantioselective addition of arylboronic acids to chromones. This enabled the facile and programmable construction of a constellation of chiral flavanones (up to 98% yield and 97% ee), in which (R)-pinostrobin was efficiently constructed without laborious protecting/deprotecting operations. Its good performance in asymmetric induction and functional tolerance expanded the chemical space of pharmaceutically important flavanones. The chiral differentiation of flavanones based on antifungal activity and a concise structure-activity relationship model was disclosed and summarized. This synergistic project culminated with acquisition of the naturally unprecedented flavanones with better antifungal potentials than sakuranetin, in which the R-enantiomer of flavanone 54 (EC₅₀ = 0.8 μM) demonstrated better performance than boscalid against Rhizoctonia solani. The novel scaffold and predicted new target compared with the commercial fungicides in the FRAC reinforce the value of further exploration.

Palladium Catalyzed Enantioselective Hayashi-Miyaura Reaction for Pharmaceutically Important 4-Aryl-3,4-dihydrocoumarins

The first palladium-catalyzed asymmetric addition of arylboronic acids to coumarins was successfully established, providing a straightforward asymmetric approach to achieving pharmaceutically important 4-aryl-3,4-dihydrocoumarins. This methodology features easily accessible and bench-stable ligands, a wide substrate scope, mild conditions, and accommodation of electron-withdrawing arylboronic acids.

The first N-ligand assisted Pd catalyzed asymmetric synthesis of 3-arylsuccinimides as novel antifungal leads

The first palladium/chiral nitrogenous ligand-catalyzed enantioselective addition of aryl boronic acids to various maleimides was reported.

Recent developments in asymmetric Heck type cyclization reactions for constructions of complex molecules

Intramolecular carbometallation-initiated asymmetric transformations are a general and powerful approach for the construction of carbo- and heterocyclic systems with one and more stereocenters. In addition, the newly developed multiple cascade reactions are an attractive strategy for increasing the molecular complexity in one step. In recent years, great progress has been made in this area with the use of various palladium and nickel complexes with P- and N-donor chiral ligands. This review highlights recent developments in intramolecular asymmetric Heck reactions, reductive Heck reactions and various types of cascade transformations (intramolecular Heck/Heck, Heck/nucleophilic trapping, Heck/Tsuji-Trost, Heck/Suzuki-Miyaura, Heck/Sonogashira, and Heck/carbonylation) in the synthesis of complex molecules over the past 5 years. A number of examples from before 2016 are included as background information. Particular attention is paid to the use of inexpensive nickel complexes as highly efficient catalysts for a number of asymmetric reactions considered here. A perspective on current challenges and potential future developments in the field of asymmetric Heck type cyclizations is also provided.

Detectives and helpers: Natural products as resources for chemical probes and compound libraries

About 70% of the drugs in use are derived from natural products, either used directly or in chemically modified form. Among all possible small molecules (not greater than 5 kDa), only a few of them are biologically active. Natural product libraries may have a higher rate of finding "hits" than synthetic libraries, even with the use of fewer compounds. This is due to the complementarity between the "chemical space" of small molecules and biological macromolecules such as proteins, DNA and RNA, in addition to the three-dimensional complexity of NPs. Chemical probes are molecules which aid in the elucidation of the biological mechanisms behind the action of drugs or drug-like molecules by binding with macromolecular/cellular interaction partners. Probe development and application have been spurred by advancements in photoaffinity label synthesis, affinity chromatography, activity based protein profiling (ABPP) and instrumental methods such as cellular thermal shift assay (CETSA) and advanced/hyphenated mass spectrometry (MS) techniques, as well as genome sequencing and bioengineering technologies. In this review, we restrict ourselves to a survey of natural products (including peptides/mini-proteins and excluding antibodies), which have been applied largely in the last 5 years for the target identification of drugs/drug-like molecules used in research on infectious diseases, and the description of their mechanisms of action.

Natural carbolines inspired the discovery of chiral CarOx ligands for asymmetric synthesis and antifungal leads

Natural carboline-inspired novel chiral β-CarOx ligands were designed and synthesized for asymmetric synthesis and discovery of antifungal leads.

Enantioselective total synthesis, divergent optimization and preliminary biological evaluation of (indole-N-alkyl)-diketopiperazines

The first enantioselective total synthesis of the antifungal natural product (indole-N-isoprenyl)-tryptophan-valine diketopiperazine 5 was accomplished. Four stereoisomers of 5 were intentionally prepared, and the (R, R)-isomer is more favorable in enhancing the antifungal bioactivity. Divergent structural optimization of this attractive model was conducted from the chiral pool amino acids. Fine-tuning of the structure protruded the broad-spectrum antifungal 6b, which also showed good preventative efficacy against Sclerotinia scleotiorum. Compound 5d could accelerate both hypocotyl elongation and root growth of Eclipta prostrata even at the concentration of <2.5 ppm. This unique and easily accessible scaffold will be of prime importance in achieving agrochemical candidates with the novel scaffold.

Late-Stage C-H Functionalization of Nicotinamides for the Expedient Discovery of Novel Antifungal Leads

Encouraged by the successful flexible modifications of the succinate dehydrogenase inhibitors, antifungal activity guided by the divergent synthesis of nicotinamides of the prevalidated pharmacophore 2-(2-oxazolinyl)aniline was conducted. The work highlighted the first utilization of the late-stage C-H functionalization assisted by the innate pharmacophore for the discovery of promising agrochemicals. New synthetic methodology and antifungal exploration of alkoxylated nicotinamides were accomplished. Fifty-five functionalized nicotinamides of 7 types were rationally designed and efficiently prepared through C-H functionalization, which facilitated the acquirement of four N-para aryloxylated nicotinamides (E3, E13, E19, and E22) as potential antifungal candidates against Botrytis cinerea, with the EC₅₀ values lower than 5 mg/L. In vivo/vitro biotest, molecular docking, and structural analysis reconfirmed the novelty and practical potential of the antifungal candidates E3 and E19. This operationally simple platform will provide various "polar parts" and offer intriguing opportunities for the optimization of the carboxamide fungicides and structure-related pharmaceuticals.