FaFrit

Intramolecular aryl–aryl coupling is the key transformation in the rational synthesis of nanographenes and nanoribbons. In this respect the C−F bond activation was shown to be a versatile alternative enabling the synthesis of several unique carbon-based nanostructures. Herein we describe an unprecedentedly challenging transformation showing that the C−F bond activation by aluminum oxide allows highly effective domino-like C−C bond formation. Despite the flexible nature of oligophenylene-based precursors efficient regioselective zipping to the target nanostructures was achieved. We show that fluorine positions in the precursor structure unambiguously dictate the “running of the zipping-program” which results in rolling-up of linear oligophenylene chains around phenyl moieties yielding target nanographenes. The high efficiency of zipping makes this approach attractive for the synthesis of unsubstituted nanographenes which are difficult to obtain in pure form by other methods.

Roll up, roll up: Virtually linear fluorinated oligophenylenes are converted into the “preprogrammed” challenging nanographenes via effective domino-like aryl–aryl coupling. The fluorine positions in the precursor structure unambiguously dictate the running of the “HF-zipping-program” leading to the formation of the target nanographene structure.

A catenane-based organocatalyst shows excellent stereoselectivity in the transfer hydrogenation of quinolines. In their Communication (DOI: 10.1002/anie.201704647), J. Niemeyer and co-workers report the first application of a catenane catalyst in asymmetric catalysis. The bifunctional catenane shows superior stereoselectivity in comparison to its non-interlocked analogues. DFT calculations indicate involvement of both catalytically active groups as the reason for the high stereoselectivity.

Ergothioneine is a sulfur metabolite that occurs in microorganisms, fungi, plants, and animals. The physiological function of ergothioneine is not clear. In recent years broad scientific consensus has formed around the idea that cellular ergothioneine primarily protects against reactive oxygen species. Herein we provide evidence that this focus on oxygen chemistry may be too narrow. We describe two enzymes from the strictly anaerobic green sulfur bacterium Chlorobium limicola that mediate oxygen-independent biosynthesis of ergothioneine. This anoxic origin suggests that ergothioneine is also important for oxygen-independent life. Furthermore, one of the discovered ergothioneine biosynthetic enzymes provides the first example of a rhodanese-like enzyme that transfers sulfur to non-activated carbon.

Without oxygen: The sulfur metabolite ergothioneine is a ubiquitous scavenger of reactive oxygen species. Discovery of ergothioneine production in strictly anaerobic bacteria and archaea suggests that ergothioneine is also important for anoxic life.