Here we report the stepwise synthesis of new nanographenes (NGs) and polycyclic aromatic hydrocarbons (PAHs) obtained via Scholl ring fusion applied at aromatic homologation compounds, which are obtained through one-step Ni-catalysed Csp2 -F functionalization. The latter are rapidly accessed valid precursors for the Scholl reaction, and screening of experimental conditions allowed us to describe for the first time furanol-bearing PAHs. Mechanistic insights are obtained by DFT to rationalize the formation of the furanol PAHs under moderately acidic conditions. All PAHs and NGs synthesized show moderate/weak fluorescent properties, and all PAHs crystallized show some degree of curvature and are obtained as racemic mixtures. Enantiomeric separation by chiral HPLC of one furanol-bearing PAH allowed the study of their chiroptical CD properties.

Herein, we describe the trifluoro‐ and difluoroethoxylation of C(sp2)‐H bonds using nickel(II) complexes incorporating a model macrocyclic arene substrate. Due to the coordinative properties of the macrocyclic substrate, we were able to detect and characterize the just‐formed C(sp2)−OCH2CF3−Ni(II) species by HRMS and IRPD. DFT studies on the C(sp2)−OCH2CF3 bond formation mechanism indicate that it involves a Ni(III)/Ni(I) reductive elimination followed by oxidation to Ni(II) rather than the higher energy barrier Ni(IV)/Ni(II) reductive elimination. This mechanistic investigation deepens the versatile redox abilities of Ni compounds and might help in designing new catalysts for the 2,2,2‐trifluoroethoxylation and 2,2‐difluoroethoxylation of arene C−H bonds.

Cobalt-catalyzed C-H amination via M-nitrenoid species is spiking the interest of the research community. Understanding this process at a molecular level is a challenging task, and here we report a well-defined macrocyclic system featuring a pseudo-Oh aryl-CoIII species that reacts with aliphatic azides to effect intramolecular Csp2-N bond formation. Strikingly, a putative aryl-Co═NR nitrenoid intermediate species is formed and is rapidly trapped by a carboxylate ligand to form a carboxylate masked-nitrene, which functions as a shortcut to stabilize and guide the reaction to productive intramolecular Csp2-N bond formation. On one hand, several intermediate species featuring the Csp2-N bond formed have been isolated and structurally characterized, and the essential role of the carboxylate ligand has been proven. Complementarily, a thorough density functional theory study of the Csp2-N bond formation mechanism explains at the molecular level the key role of the carboxylate-masked nitrene species, which is essential to tame the metastability of the putative aryl-CoIII═NR nitrene species to effectively yield the Csp2-N products. The solid molecular mechanistic scheme determined for the Csp2-N bond forming reaction is fully supported by both experimental and computation complementary studies.

A Ni-catalyzed C-sp2-OMe ortho-functionalization methodology to form chemoselectively alkyne monoannulation or aromatic homologation products is reported as a novel protocol towards the valorisation of substrates containing C-sp2-OMe units. Double activation of C-sp2-OMe and C-sp2-F bonds is also demonstrated. Further use of aromatic homologation products towards the synthesis of nanographene-like compounds is described.

This work summarizes the most relevant examples of high-valent copper, silver and gold coordination compounds. It covers compounds from non-organometallic species, relevant for instance to the bioinorganic field for copper, to the organometallic Cu(III), Ag(III) and Au(III) species involved in important catalytic transformations, mainly cross-coupling and CH activation catalysis. Ample discussion on the geometric requirements for the stabilization of M(III) (M = Cu, Ag, Au) is provided. Moreover, examples of organometallic fundamental steps are described for the three metals, as well as their involvement in catalytic cycles for CC and C-heteroatom coupling processes.

A secondary phosphine oxide (SPO)-nickel catalyst allowed the activation of otherwise inert C-F bonds of unactivated arenes in terms of challenging couplings with primary and secondary alkyl Grignard reagents. The C-F activation is characterized by mild reaction conditions and high levels of branched selectivity. Electron-rich and electron-deficient arenes were suitable electrophiles for this transformation. In addition, this strategy also proved suitable to heterocycles and for the activation of C-O bonds under slightly modified conditions.

Fluorinated compounds are key structural moieties in numerous areas of chemistry, with applications to catalysis, medicine and material sciences.[1] The introduction of fluorinated motifs changes properties of a given molecule, and in the pharmaceutical industry context, improves the stability and lifetime of F-containing pharmaceuticals. However, the stability is often too pronounced and the lead compound is frequently poorly biodegradable. Therefore, it is furthermore desirable to develop new sustainable methods for the functionalization of aromatic C-F bonds, as a useful strategy to establish novel chemical transformation of aryl fluorides. Transition metal-catalyzed Ar–F functionalization is considerably more challenging than classical Ar-H or Ar–Hal (Hal = I, Br, Cl) activation, generally showing low selectivities and requiring electronically biased polyfluorinated substrates.[2] In particular, C–C formation reaction via C–F cleavage of fluoroarenes using nickel catalyst has been reported using activated aryl nucleophiles, such as highly reactive Grignard reagents, zincates and boronic acids as the coupling partner for C–C formation via transmetallation [3]. Herein we show Nickel-catalyzed C–F activations enabled chemo-divergent C–C formation with alkynes by chelation assistance. The judicious choice of the alkynes electronic properties thus allowed the selective synthesis of alkyne mono-annulation or doubleinsertion aromatic homologation products. A key unprecedented 9-membered nickelocyclic intermediate species was isolated and crystalized, unravelling the mechanistic pathway to the aromatic homologation product by challenging double CF/C-H activation.

Cross-coupling transformations are a powerful tool in organic synthesis. It is known that this kind of transformation undergoes 2-electron redox processes, and, for this reason, silver has been nearly forgotten as catalyst for cross-couplings because silver is mainly considered as a 1-electron redox metal. Herein, we disclose effective Ag(I)-catalyzed cross-coupling transformations using bidentate aminoquinoline as a directing group toward different nucleophiles to form C–C, C–N, and C–O bonds. DFT calculations indicate the feasible oxidative addition of L1-I substrate via the Ag(I)/Ag(III) catalytic cycle. Furthermore, ion spectroscopy experiments suggest a highly reactive aryl-Ag(III) that in the absence of nucleophiles reacts to form an intermolecular cyclic product [5d-Ag(I)-CH3CN], which in solution forms 5a. This work proves that silver can undergo 2-electron redox processes in cross-coupling reactions like Pd and Cu.