Rational design, synthesis and binding mechanisms of novel benzyl geranate derivatives as potential eco-friendly aphid repellents.

Background: The push-pull strategy is considered as a promising eco-friendly method for pest management. Plant volatile organic compounds (PVOCs) act as semiochemicals constitute the key factor in implementing this strategy. Benzyl alcohol and geraniol, as functional PVOCs, were reported to regulate insect behavior, showing the potential application in pest control.

Association of hormone replacement therapy and the risk of knee osteoarthritis: A meta-analysis.

Background: The relationship between hormone replacement therapy (HRT) and osteoarthritis is controversial in epidemiological studies. With the aim of better understanding the effect of HRT use, this first meta-analysis was implemented to explore the association of HRT and knee OA.

Methods: A series of data is retrieved from Web of Science, PubMed, and Embase databases to observe the association of HRT and knee osteoarthritis up to December 2021.

Taming Chiral Quaternary Stereocenters via Remote H-Bonding Stereoinduction in Palladium-Catalyzed (3+2) Cycloadditions.

Ring-opening transformations of donor-acceptor (D-A) cyclopropanes enable the rapid assembly of complex molecules. However, the enantioselective formation of chiral quaternary stereocenters using substrates bearing two different acceptors remains a challenge. Herein, we describe the first palladium-catalyzed highly diastereo- and enantioselective (3+2) cycloaddition of vinyl cyclopropanes bearing two different electron-withdrawing groups, a subset of D-A cyclopropanes.

Cooperative Ligand-Promoted P-Directed Ruthenium-Catalyzed Remote -C-H Alkylation of Tertiary Phosphines.

Herein, we disclose a ruthenium-catalyzed -selective C-H activation of phosphines by using intrinsic P as a directing group. 2,2,6,6-Tetramethylheptane-3,5-dione acts as the ligand and exhibits an excellent performance in boosting the -alkylation. The protocol allows an efficient and straightforward synthesis of -alkylated tertiary phosphines.

Remote and Selective C(sp)-H Olefination for Sequential Regioselective Linkage of Phenanthrenes.

Biphenylcarboxylic acid with two competing C(sp)-H sites was designed for site selective C(sp)-H functionalization by developing carboxylic acids assisted remote and selective olefination via 7-membered palladacycle. Mechanism investigation and DFT calculations reveal a kinetics-determined process, which could be utilized to explore a variety of remote site selectivity. The practicability of this method was highlighted by the precise construction of phenathrene under sequential site selectivity.

Carboxylate-Assisted Pd(II)-Catalyzed ortho-C-H and Remote C-H Activation: Economical Synthesis of Pyrano[4,3- b]Indol-1(5 H)-ones.

An original Pd(II)-catalyzed domino two C-H activations strategy has been designed to synthesize pyrano[4,3- b]indol-1(5 H)-one motifs from inexpensive and commercially available olefins and heteroaromatic acids by carboxylate-directed sequential ortho-C-H alkenylation and remote C-H lactonization. Importantly, this protocol overcomes the selectivity for carboxylic acids with acrylates of the conventional Michael addition-type process. Preliminary studies of mechanism indicate that both aryl and olefinlic C-H activations may participate in this catalytic system.

Facile synthesis of unnatural β-germyl-α-amino amides via Pd(ii)-catalyzed primary and secondary C(sp)-H bond germylation.

Pd(ii)-Catalyzed direct C(sp3)-H germylation of α-AA derivatives with the assistance of a bidentate auxiliary for the efficient synthesis of β-germyl-α-amino amides is reported. This protocol features good generality for primary and secondary C-H bonds of aliphatic amides. Mechanistic studies show that a crucial five-membered palladacycle intermediate may play a key role in this process.

Monoprotected Amino Acid (MPAA) Ligand Enabled C-H Alkynylation of Phenyl Acetic Acid.

A weakly carboxylate-directed palladium(II)-catalyzed ortho-C-H alkynylation of diverse phenylacetic acids promoted by monoprotected amino acid ligand enabled is reported. The reaction has a broad substrate scope including α-secondary, tertiary, and quaternary phenylacetic acids. Notably, the direct ortho-C-H alkynylation of α-quaternary phenylacetic acids and chiral α-tertiary phenylacetic acids was achieved for the first time.