Immobilized sterically demanding NHC-Au(I) complexes silica-[(IPr R )Au]Cl and silica-[(IAdPr R )Au]Cl are synthesized and characterized. These complexes are suitable catalysts in typical homogeneous Au(I)-catalyzed alkyne reactions such as hydration, hydroamination, hydroarylation, or cycloisomerization. The results obtained with the immobilized catalysts in reactions in batch are comparable to those obtained with their homogeneous counterparts with the advantage of easily recovered and recycled in successive reactions. Their catalytic activity decreases when reused in batch reactions, probably because of crushing that is associated with magnetic stirring. In contrast, these immobilized catalysts are very effective when used under continuous flow conditions in which the same cartridge can be used to catalyze different types of reaction successively for a long period without any noticeable loss of activity.

The C‐C ring closure of α‐chloromethyl alkyl or aryl N‐aryl imines catalyzed with 1 to 10 % Pd(OAc)2/P(p‐tolyl)3 afford efficiently 2‐aryl‐ and 2‐alkyl‐1H‐indoles. The heterocyclization reaction involves the initial formation of [2‐(arylimino)ethyl]palladium(II) chloride complexes with subsequent C‐H activation of the aromatic amine ring. Readily or commercially available α‐chloromethyl‐aryl or ‐alkyl ketones are used as the precursors. Functionalized indoles at the benzene ring are obtained when the imines are derived from substituted anilines.

Advances in molecular probes have recently intensified because they are valuable tools in studying species of interest for human health, the environment, and industry. Among these species, cyanide (CN–) and fluoride (F–) stand out as hazardous and toxic ions in trace amounts. Thus, there is a significant interest in probes design for their detection with diverse diazoles (pyrazole and imidazole) used for this purpose. These diazole derivatives are known as functional molecules because of their known synthetic versatility and applicability, as they exhibit essential photophysical properties with helpful recognition centers. This review provides an overview of the recent progress (2017–2021) in diazole-based sensors for CN– and F– detection, using the azolic ring as a signaling or recognition unit. The discussion turns to the mechanism of the action described for recognizing the anion, the structure of the probes with the best synthetic simplicity, detection limits (LODs), application, and selectivity. In this context, the analysis involves probes for cyanide sensing first, then probes for fluoride sensing, and ultimately, dual probes that allow both species recognition.

The selectivity of a catalytic alkane functionalization process can be modified just changing the reaction medium from neat alkane to supercritical carbon dioxide (scCO2). A silica supported copper complex bearing an N-heterocyclic carbene ligand promotes the functionalization of carbon–hydrogen bonds of alkanes by transferring the CHCO2Et group from N2CHCO2Et (ethyl diazoacetate, EDA). In neat hexane, only 3% of the primary C–H bonds (ethyl heptanoate being the product) are functionalized in that manner, whereas the same reaction carried out in scCO2 provides a 30% yield in this linear ester. Such an effect seems to be induced by an electronic density flux from the NHC ligand to the surrounding carbon dioxide molecules.

α-Chloromethylketimines have been obtained through a gold-catalyzed hydroamination of aromatic and aliphatic 1-chloroalkynes with aromatic amines by using equimolar amounts of both reagents. This procedure has allowed the preparation and spectroscopic characterization of α-chloromethylketimines for the first time with a high degree of purity, complete conversion, and atom economy. The synthetic usefulness of the methodology has been demonstrated with the preparation of β-chloroamines and indoles.