Benzoquinone Enhances Hyperpolarization of Surface Alcohols with Para-Hydrogen

The nuclear singlet state of H₂, para-hydrogen, can be used to increase the measurable signal-to-noise for magnetic resonance techniques─a form of hyperpolarization. Transfer of this polarization from para-hydrogen to alcohols through surface interactions rather than formal hydrogenation has only been demonstrated on heterogeneous catalysts tailored to minimize loss of spin order. Here, we find that a common platinum-on-carbon catalyst is capable of this interaction and that the addition of a benzoquinone significantly increases the signal output of hyperpolarized methanol or water.

Hydroxy Groups Enhance [2]Rotaxane Anion Binding Selectivity

We report the synthesis of two [2]rotaxanes containing an interlocked three dimensional binding cavity formed from a pyridinium bis(amide) axle component containing two phenol donors, and an isophthalamide based macrocycle. In the competitive solvent mixture 1 : 1 CDCl₃ : CD₃OD, one of the receptors exhibits a much higher selectivity preference for chloride than an analogous rotaxane without the hydroxy groups. X‐ray crystal structures reveal the chloride anion guest encapsulated within the interlocked binding cavity, though not all of the hydrogen bond donors are utilised. Computational semi‐empirical simulations indicate that secondary intermolecular interactions occur between the axle hydroxy hydrogen bond donors and the [2]rotaxane macrocycle components, contributing to a more preorganised binding pocket, which may be responsible for the observed enhanced selectivity.

The Different Facets of Metal-Catalyzed C-H Functionalization Involving Quinone Compounds

Metal-catalysed C-H functionalization has emerged as a powerful platform for the derivatization of quinones, a class of compounds with wide-ranging applications. This review organises and discusses the evolution of this chemistry from early Fujiwara-Moritani reactions, through to modern directing-group assisted C-H functionalization processes, including C-H functionalization reactions directed by the quinone ring itself. Mechanistic details of these reactions are provided to afford insight into how the unique reactivity of quinoidal compounds has been leveraged in each example.

Organic synthesis reactions on-water at the organic–liquid water interface

Organic synthesis on-water has shown surprising successful synthetic methods. This review discusses the array of chemistry, which has been adapted with this methodology.