Gold nanoparticle-catalysed functionalization of carbon-hydrogen bonds by carbene transfer reactions

Gold nanoparticles stabilized by NHC ligands and supported onto reduced graphene oxide (rGO) catalyse the functionalization of cyclohexane and benzene C-H bonds upon insertion of carbene CHCO₂Et (from N₂CHCO₂Et) groups. This is the first example in which such C_sp3-H or C_sp2-H bonds are functionalized with this strategy with nanoparticulated gold. This Au-NP@rGO material shows an exceptional activity, providing TON values 5-10 times higher than those already reported for molecular gold catalysts. Recyclability is also effective, reaching an accumulated TON value of 1400 after six consecutive uses.

PIII-Mediated intramolecular cyclopropanation and metal-free synthesis of cyclopropane-fused heterocycles

The carbene-like reactivity of the Kukhtin–Ramirez adduct enables the first reductive intramolecular cyclopropanation, which provides easy access to highly functionalized cyclopropane-fused heterocycles.

Site Selectivity in Pd-Catalyzed Reactions of α-Diazo-α-(methoxycarbonyl)acetamides: Effects of Catalysts and Substrate Substitution in the Synthesis of Oxindoles and β-Lactams

The Pd-catalyzed intramolecular carbene C–H insertion of α-diazo-α-(methoxycarbonyl)acetamides to prepare oxindoles as well as β-lactams was studied. In order to identify what factors influence the selectivity of the processes, we explored how the reactions are affected by the catalyst type, using two oxidation states of Pd and a variety of ligands. It was found that, in the synthesis of oxindoles, ((IMes)Pd(NQ))₂ can be used as an alternative to Pd₂(dba)₃ to catalyze the carbene C_Arsp²–H insertion, although it was less versatile. On the other hand, it was demonstrated that the Csp³–H insertion leading to β-lactams can be effectively promoted by both Pd(0) and Pd(II) catalysts, the latter being most efficient. Insight into the reaction mechanisms involved in these transformations was provided by DFT calculations.

Grubbs catalysts in intramolecular carbene C(sp3)-H insertion reactions from α-diazoesters

Grubbs catalysts are described as a useful alternative to promote intramolecular carbene C-H insertion from α-diazoesters. Moreover, no competition arises from the possible metathesis reactions on substrates bearing alkene and alkyne moieties. DFT calculations were also carried out to gain insight into the reaction mechanism involved in these transformations.

Catalytic alkylation of unactivated C(sp3)–H bonds for C(sp3)–C(sp3) bond formation

This review summarizes recent advancements in catalytic direct transformation of unactivated C(sp³)–H bonds into C(sp³)–C(sp³) bonds.

Biosynthesis of palladium nanoparticles using Poplar leaf extract and its application in Suzuki coupling reaction

A green route for the synthesis of palladium (Pd) nanoparticles (Pd NPs) employing Poplar leaf extract as a reducing and capping agent is described. The as-prepared Pd NPs are spherical with a face centred cubic structure, a particle distribution of 2.2-6.8 nm and an average particle size of 4.2 nm. The application of this catalyst toward homogeneous Suzuki coupling reactions was investigated. The Pd NPs afforded a yield of 98.86% in the Suzuki coupling reaction of 4-bromotoluene with phenylboronic acid using 0.01 mmol% of the catalyst at 60°C for 30 min under an air atmosphere.

Palladium-catalysed intramolecular carbenoid insertion of α-diazo-α-(methoxycarbonyl)acetanilides for oxindole synthesis

A novel, selective palladium-catalysed carbenoid C(aryl)–H insertion of α-diazo-α-(methoxycarbonyl)acetanilides leading to oxindoles is described.

Palladium stabilized by 3,4-dihydroxypyridine-functionalized magnetic Fe3O4nanoparticles as a reusable and efficient heterogeneous catalyst for Suzuki reactions

A Pd supported on 3,4-dihydroxypyridine (Py)-functionalized Fe₃O₄(Fe₃O₄/Py/Pd) hybrid material has been synthesized for the first time.

Catalytic functionalization of low reactive C(sp(3))-H and C(sp(2))-H bonds of alkanes and arenes by carbene transfer from diazo compounds

The direct functionalization of low reactive C(sp(3))-H and C(sp(2))-H bonds of alkanes and arenes, respectively, by metal-induced carbene transfer from diazo compounds is reviewed. To date, this methodology has enabled the incorporation of CR(1)R(2) moieties from N2[double bond, length as m-dash]CR(1)R(2) in a chemo, regio, enantio or diastereoselective manner in those substrates with the appropriate selection of metal and ligands.