Air-Stable Oxyallyl Patterns and a Switchable N-Heterocyclic Carbene.

Oxyallyl derivatives are typically elusive compounds. Even recently reported "stabilized" 1,3-diaminooxyallyl species are still highly reactive and have short lifetimes at room temperature. Herein, we report the synthesis and preliminary study of mesoionic pyrimidine derivatives that feature 1,3-bis(dimethylamino)oxyallyl patterns with an unprecedented level of stabilization.

What Are the Radical Intermediates in Oxidative N-Heterocyclic Carbene Organocatalysis?

The oxidation of the Breslow intermediate resulting from the addition of an N-heterocyclic carbene (NHC) to benzaldehyde triggers a fast deprotonation, followed by a second electron transfer, directly affording the corresponding acylium at E > -0.8 V (versus Fc/Fc). Similarly, the oxidation of the cinnamaldehyde analogue occurs at an even higher potential and is not a reversible electrochemical process.

Metal free oxidation of vinamidine derivatives: a simple synthesis of α-keto-β-diimine ligands.

Oxidation of vinamidinium salts with -chloroperbenzoic acid is the key synthetic step towards new persistent 1,3-di(amino)oxyallyl radical cations. When applied to parent vinamidines, this protocol allows for a simple straightforward synthesis of α-keto-β-diimine ligands, for which no convenient synthesis was previously available.

Stable Di- and Tri-coordinated Carbon(II) Supported by an Electron-Rich β-Diketiminate Ligand.

Complexes of the ubiquitous β-diketiminates (NacNac) ligands have been reported with most elements of the periodic table, including Group 14 Si, Ge, Sn, and Pb. The striking absence of carbon representatives has been attributed to the extreme electrophilicity of the putative C-NacNac adducts. An electron enriched 2,4-(dimethylamino)diketiminato backbone is described, which allowed for the synthesis and isolation of such stable pyrimidin-1,3-diium and pyrimidinium-2-ylidene salts.

An air-persistent oxyallyl radical cation with simple di(methyl)amino substituents.

We report an experimental and theoretical study of the 1,1,3,3-tetrakis-di(methylamino)oxyallyl radical cation. Despite simple substituents with minimal steric hindrance, this radical was found to be stable under an inert atmosphere and persistent for several hours in well-aerated solutions.