Polyethylene glycol (PEG)-coated (pegylated) gold nanoparticles (AuNPs) have been proposed as drug carriers and diagnostic contrast agents. However, the impact of particle characteristics on the biodistribution and pharmacokinetics of pegylated AuNPs is not clear. We investigated the effects of PEG molecular weight, type of anchoring ligand, and particle size on the assembly properties and colloidal stability of PEG-coated AuNPs. The pharmacokinetics and biodistribution of the most stable PEG-coated AuNPs in nude mice bearing subcutaneous A431 squamous tumors were further studied using 111 In-labeled AuNPs. AuNPs coated with thioctic acid (TA)-anchored PEG exhibited higher colloidal stability in phosphate-buffered saline in the presence of dithiothreitol than did AuNPs coated with monothiol-anchored PEG. AuNPs coated with high-molecular-weight (5000 Da) PEG were more stable than AuNPs coated with low-molecular-weight (2000 Da) PEG. Of the 20-nm, 40-nm, and 80-nm AuNPs coated with TA-terminated PEG 5000 , the 20-nm AuNPs exhibited the lowest uptake by reticuloendothelial cells and the slowest clearance from the body. Moreover, the 20-nm AuNPs coated with TA-terminated PEG 5000 showed significantly higher tumor uptake and extravasation from the tumor blood vessels than did the 40-and 80-nm AuNPs. Thus, 20-nm AuNPs coated with TA-terminated PEG 5000 are promising potential drug delivery vehicles and diagnostic imaging agents.

In the presence of catalytic [Ru(p-cym)I2 ]2 and the base guanidine carbonate, benzoic acids react with internal alkynes to give the corresponding 2-vinylbenzoic acids. This alkyne hydroarylation is generally applicable to diversely substituted electron-rich and electron-poor benzoic and acrylic acids. Aryl(alkyl)acetylenes react regioselectively with formation of the alkyl-branched hydroarylation products, and propargylic alcohols are converted into γ-alkylidene-δ-lactones. The hydroarylation can also be conducted decarboxylatively with a different choice of catalyst and reaction conditions. This reaction variant, which does not proceed via intermediate formation of 2-vinylbenzoic acids, opens up a regioselective, waste-minimized synthetic entry to vinylarenes.

A Ru-catalyzed selective and atom-economic ortho-C–H allylation of aromatic acids with vinylcyclopropanes is reported. The reaction proceeds with selective cleavage of both a C–H and a C–C bond. A wide range of allylarenes were synthesized in high yields and stereoselectivities. The vinylcyclopropane substrates can optionally be generated in situ from a diazo compound and 1,3-butadiene. Concise syntheses of isocoumarin and 3,4-dihydroisocoumarin derivatives underline the synthetic utility of the reaction.

A ruthenium-catalysed ortho-C–H allylation of benzoic acids is disclosed that makes use of unactivated allyl alcohols or seemingly inert allyl methyl ethers as allylating agents.

An efficient and generally applicable protocol for the palladacycle-catalyzed arylation of diisopropyl H-phosphonate in water was developed. The remarkable features of this C-P bond-forming reaction include wide substrate scope including the inactive electron-rich and electron-neutral aryl chlorides, the weak inorganic base KF instead of strong bases such as KO t Bu or NaO t Bu for the activation of C-Cl bond, and the addition of isopropanol to avoid the decomposition of diisopropyl H-phosphonate.

In the presence of catalytic [RuCl (p-cym)] and using Li PO as the base, benzoic acids react with olefins in water to afford the corresponding 2-alkylbenzoic acids in moderate to excellent yields. This C-H alkylation process is generally applicable to diversely substituted electron-rich and electron-deficient benzoic acids, along with α,β-unsaturated olefins including unprotected acrylic acid. The widely available carboxylate directing group can be removed or utilized for further derivatization. Mechanistic investigations revealed that the transformation proceeds via a ruthenacycle intermediate.

A facile insertion of ruthenium into aromatic C-H and allylic C-N bonds are the key steps in a [Ru( p-cymene)Cl]-catalyzed ortho-C-H allylation of benzoic acids. This protocol allows drawing on the large pool of allylic amines for state-of-the-art ortho-functionalizations of arenes, turning neutral amines into leaving groups. Concise syntheses of biologically active compounds provide further evidence of the synthetic potential of this methodology.

The utilization of carbon dioxide as a building block in organic synthesis has become a highly sought‐after research area. In this minireview, an overview of recent advances on carboxylations using carbon dioxide via visible light photoredox and transition‐metal dual catalysis is given. The merging of these methods provides new avenues to construct carboxylates.