In this issue, N. Budisa et al. review biocatalysis with unnatural amino acids. What happens when enzymology meets xenobiology? In a Minireview, B. P. Fors et al. discuss cationic polymerization, its photoinitiation, and its photocontrol. In an Essay, D. E. Lewis looks back on a century of pyridine chemistry, initiated by the works of A. Y. Chichibabin. The Highlight deals with the intermolecular formation of two C–C bonds across olefins (D. Hidasová and U. Jahn).

In the Communications section, W. Lin et al. describe how the surface modification of two-dimensional metal–organic layers creates biomimetic catalytic microenvironments for selective oxidation reactions (see picture). A. Gansäuer et al. investigated S_N2 reactions at tertiary carbon centers in epoxides. J. L. Lutkenhaus et al. found an unusual electron transfer in conjugated radical polymers.

• Angewandte Chemie 33/2017: Unusual Transfers,
  Angew. Chem. Int. Ed. 2017, 56 (33).