Cover Picture: Cobalt(I)‐Catalyzed Asymmetric [2+2+2] Cycloaddition of Alkynes and Nitriles: Synthesis of Enantiomerically Enriched Atropoisomers of 2‐Arylpyridines (Angew. Chem. Int. Ed. 29/2004)

Abstract

Nature decided in favor of the left‐handed helical isomer for the hop vine shown in the cover picture. In contrast, the [2 + 2 + 2] cycloaddition yielding biaryl nitrogen heterocycles gives access to both enantiomers. In their Communication on p. 3795 ff. A. Gutnov, B. Heller et al. describe this photochemical reaction which is conducted with a chiral cobalt catalyst. (The picture of the hop plant is taken from the book by H. Brunner, Rechts oder Links. In der Natur und anderswo, Wiley‐VCH, 1999.)