Pyridines, which comprise one of the most important classes of the six-membered heterocyclic compounds, are widely distributed in nature, and the transition-metal-catalyzed [2 + 2 + 2] cycloaddition reaction of two alkynes and a nitrile is one of the most powerful methods for preparing versatile, highly substituted pyridine derivatives. However, the lack of chemo- and regioselectivity is still a crucial issue associated with fully intermolecular [2 + 2 + 2] cycloaddition. The present study developed the Ni(0)-catalyzed intermolecular dehydrogenative [4 + 2] cycloaddition reaction of 1,3-butadienes with nitriles to give a variety of pyridines regioselectively.

Trifluorovinylzinc is a common synthetic intermediate for trifluorovinyl derivatives, including α,β,β-trifluorostyrenes and hexafluorobutadiene. Here, we report a novel synthetic approach for the formation of trifluorovinylzinc chloride via a C–F bond activation of tetrafluoroethylene (TFE), which is an industrially cost-effective bulk feedstock with a negligible GWP. The present system provides a practical synthetic route to various trifluorovinyl derivatives with very low energy consumption.

Nickel-Catalyzed Dehydrogenative [4 + 2] Cycloaddition of 1,3-Dienes with Nitriles. -The title reaction allows an efficient and regioselective access to a wide range of pyridines. The formation of di-and tripyridine derivatives is also possible. -(OHASHI, M.; TAKEDA, I.; IKAWA, M.; OGOSHI*, S.; J. Am. Chem. Soc. 133 (2011) 45, 18018-18021, http://dx.