In this issue, C. C. Nawrat and C. J. Moody review the use of quinones as dienophiles in the Diels–Alder reaction. How has this rection become a pivotal step in the total synthesis of natural products and other complex molecules? In a Minireview, A. Das and S. Ghosh discuss supramolecular charge-transfer assemblies of chromophores. The Highlight deals with the copper-catalyzed hydroamination of alkenes with hydroxylamines.
In the Communications section, H. Schwalbe et al. report on the characterization of the decay kinetics of metarhodopsin states in rhodopsin by NMR spectroscopy (see picture). S. Dai et al. present ambient lithium–SO2 batteries with ionic-liquid electrolytes. D. F. Perepichka et al. succeeded in the crystal engineering of organic semiconductors by hydrogen bonding. J. J. Vittal et al. how to reversibly photochemically form and thermally cleave cyclobutadiene rings in single crystals.