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Molecular materials that possess a toroidal moment associated to a non-magnetic ground state are known as single-molecule toroics (SMTs) and are usually planar molecules. Herein, we report a Dy 4 cubane, namely [Dy 4 (Bppd) 4 (μ 3 -OH) 4 (Pa) 4 (H 2 O) 4 ]⋅0.333 H 2 O (where BppdH=1,3-Bis(pyridin-4-yl)propane-1,3-dione and PaH=2-Picolinic acid) for which magnetometry measurements and state-of-art ab initio calculations highlight SMT behavior in a tridimensional structure (3D-SMT). The in-depth theoretical analysis on the resulting low-lying energy states, along with their variation in function of the magnetic exchange pathways, allows further light to be shed on the description of single-molecule toroics and identify the coupling scheme that better reproduces the observed data., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The one-step polycondensation of diamines and diboranes triggered by the in situ deprotonation of the diammonium salts and concomitant reduction of bisboronic acids leads to the assembly of polymer chains through multiple Lewis pairing in their backbone. These new polyboramines are dihydrogen reservoirs that can be used for the hydrogenation of imines and carbonyl compounds. They also display a unique dihydrogen thermal release profile that is a direct consequence of the insertion of the amine-borane linkages in the polymeric backbone., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The high-yielding synthesis of 5-bromopenta-2,4-diynenitrile (BrC5 N) was achieved for the first time. Its reactivity with triisopropylsilylacetylene and triisopropylsilylbutadiyne in the presence of copper and palladium as co-catalysts and diisopropylamine was evaluated. It revealed an unprecedented cascade reaction leading to a diene in one case and to a benzofulvene in the other case, with a unique structure. Both of them were characterized by X-ray crystallography, among other techniques. The mechanism of the reaction leading to the diene was investigated experimentally. Theoretical calculations at the DFT level suggest that the mechanism leading to the benzofulvene relies on a hexa-dehydro Diels-Alder (HDDA)-type of mechanism. This work constitutes an example of an unanticipated reactivity leading to an important increase of chemical complexity., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

An optimized ligand-controlled palladium-catalyzed allene synthesis starting from alkynes and aryl bromides giving rise to allene products in a simple and direct manner is described. The methodology is performed in an inter- and intramolecular fashion with unprecedented scope and excellent yields. Based on mechanistic investigations and on DFT calculations, the role played by the carboxylic additive (i.e., PivOH) in controlling the selectivity of the reaction is discussed, allowing us to propose an intramolecular base-assisted deprotonation (iBAD) mechanism for this process., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The palladium-catalyzed ligand-controlled arylation of α-zincated acyclic amines, obtained by directed α-lithiation and transmetalation, is described. Whereas PtBu3 gave rise to α-arylated Boc-protected amines, more flexible N-phenylazole-based phosphine ligands induced major β-arylation through migrative cross-coupling., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The palladium-catalyzed β-arylation of ester enolates with aryl bromides was studied both experimentally and computationally. First, the effect of the ligand on the selectivity of the α/β-arylation reactions of ortho- and meta-fluorobromobenzene was described. Selective β-arylation was observed for the reaction of o-fluorobromobenzene with a range of biarylphosphine ligands, whereas α-arylation was predominantly observed with m-fluorobromobenzene for all ligands except DavePhos, which gave an approximate 1:1 mixture of α-/β-arylated products. Next, the effect of the substitution pattern of the aryl bromide reactant was studied with DavePhos as the ligand. We showed that electronic factors played a major role in the α/β-arylation selectivity, with electron-withdrawing substituents favoring β-arylation. Kinetic and deuterium-labeling experiments suggested that the rate-limiting step of β-arylation with DavePhos as the ligand was the palladium-enolate-to-homoenolate isomerization, which occurs by a βH-elimination, olefin-rotation, and olefin-insertion sequence. A dimeric oxidative-addition complex, which was shown to be catalytically competent, was isolated and structurally characterized. A common mechanism for α- and β-arylation was described by DFT calculations. With DavePhos as the ligand, the pathway leading to β-arylation was kinetically favored over the pathway leading to α-arylation, with the palladium-enolate-to-homoenolate isomerization being the rate-limiting step of the β-arylation pathway and the transition state for olefin insertion its highest point. The nature of the rate-limiting step changed with PCy(3) and PtBu(3) ligands, and with the latter, α-arylation became kinetically favored. The trend in selectivity observed experimentally with differently substituted aryl bromides agreed well with that observed from the calculations. The presence of electron-withdrawing groups on these bromides mainly affected the α-arylation pathway by disfavoring C-C reductive elimination. The higher activity of the ligands of the biaryldialkylphosphine ligands compared to their corresponding trialkylphosphines could be attributed to stabilizing interactions between the biaryl backbone of the ligands and the metal center, thereby preventing deactivation of the β-arylation pathway., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)