Crucial breakthroughs in the activation of the C(aryl)? O bond of phenol derivatives were achieved almost simultaneously by two research groups (see scheme; Cy=cyclohexyl). Garg et al. coupled a range of aryl pivalates with arylboronic acids to give unsymmetrical biaryls. Shi et al. achieved this through C(aryl)? O activation of aryl carboxylates; the best results for the coupling of aryl boroxines were again obtained with aryl pivalates.
Covalent, ionic, or something new? A new interpretation of the topology of the electron density at the bond critical point is proposed to characterize covalent, ionic, and charge‐shift bonding from the density point of view (see figure). The topological properties of the density representation confirm the reality of charge‐shift bonds, in which the covalent contribution is weak or repulsive, and most of the bonding is due to the covalent–ionic resonance energy.
Ringing the changes : The total synthesis of the title compound centers around a novel strategy that employs a nickel(0)–phosphine complex and triethyl borane in an efficient closure of a 14‐membered ring through C? C bond formation (see scheme; cod=cyclooctadiene). The synthesis was accomplished in 10 steps and in approximately 9 % overall yield.
Conditional cleavage : Photochemical S? N bond cleavage of the Zn2+ complex of N‐dansylcyclen (ZnL2) in aqueous solution was investigated. Moreover, photolysis of ZnL2 (see scheme) facilitated photoreversion of cis,syn‐thymine photodimer (T[c,s]T).
“My most exciting discovery to date has been that molecules can have a magnetic memory. The biggest challenge facing scientists is to find renewable and sustainable energy sources…?” This and more about Roberta Sessoli can be found on page 2265.
CO! You had me at hello : The use of chiral biphenyl‐based phosphoramidite ligands on rhodium provides an efficient [2+2+2] cycloaddition between terminal alkyl alkynes and alkenyl isocyanates (see scheme). The cycloaddition proceeds through a CO migration pathway, and facilitates a rapid four‐step asymmetric synthesis of indolizidine (?)‐209D.
No need for a metal : A combination of mass spectrometry and computational studies (density functional theory and coupled‐cluster methods) shows that [P4O10].+ is the first polynuclear nonmetal oxide cation that is capable of activating the C? H bond of methane at room temperature (see picture). This process represents a further example in the reactivity of oxygen‐centered radicals.
A light touch is all that is required to cleave a maleimide C? N bond to effect a [5+2] photocycloaddition with a sterically encumbered C?N moiety (see scheme).
Komplett fluoriert : Vollständig fluoriertes Pentaphenylborol (siehe Struktur) wurde durch aufeinander folgende Transmetallierungsreaktionen unter Beteiligung von Zr‐ und Sn‐Heterocyclen synthetisiert. Das hoch feuchtigkeitsempfindliche Borol ist ein neues Mitglied der Familie der Perfluorarylborane, einer Klasse von antiaromatischen Verbindungen mit grundlegender Bedeutung für Aromatizitätskonzepte.
Don't rewrite the textbooks! Vibrational spectra of a selectively deuterated derivative of phenanthrene indicate that the C4H???HC5 interaction in its “bay” area should be interpreted as steric (Pauli) repulsion. These findings and the results of theoretical analysis are in conflict with interpretations that describe this interaction as strongly stabilizing.
Charging forward : Ionic interactions presented in a multivalent fashion in small‐molecule ionic liquids lead to functional polymer‐like materials (see picture) that are consistent with the formation of a supramolecular ionic network. For example, the ionic material formed from a dication consisting of two covalently linked tetraalkyl phosphonium moieties and a porphyrin tetracarboxylate has a viscosity of 106 Pa s at 25 °C.
Funky discotics : Photoconductivity is measured in newly synthesized cyclopalladated metallomesogens exhibiting hexagonal columnar mesophases at room temperature. The tuning of the HOMO/LUMO energy levels by modification of the chain/core linkage (ester 1 vs ether 2 ) makes compound 2 photoconductive across the whole UV/Vis/NIR range.
Preferred protonation : Does electrospray ionization mass spectrometry produce gas‐phase or liquid‐phase structures? The preferred protonation site in p‐aminobenzoic acid depends upon the medium, and the structure of its conjugate acid varies with the solvent used during spraying.
