Nickel(II)-Catalyzed Selective (E)-Olefination of Methyl Heteroarenes Using Benzyl Alcohols via Acceptorless Dehydrogenative Coupling Reaction

An efficient catalytic protocol for the synthesis of selective (E)-olefins by the newly synthesized nickel complexes via greener acceptorless dehydrogenative coupling methodology is presented. Two nickel(II) N, S chelating complexes were structurally characterized with the aid of spectral and single crystal X-ray diffraction methods. Olefination of 2-methylheteroarenes with benzyl alcohols via acceptorless dehydrogenative coupling is achieved by inexpensive nickel(II) catalysts. The present olefination protocol is simple and furnishes the desired 2-alkenylheteroarenes in 35 h and yields in the range of 40-93 %. The dehydrogenative coupling reaction proceeds via the generation of an aldehyde intermediate and produces water and hydrogen as sole by-products. The wide substrate scope of this catalytic reaction covered the synthesis of drug intermediates.

Automated summary

A new nickel complex catalyst is used for the synthesis of (E)-olefins via greener acceptorless dehydrogenative coupling methodology. This simple and efficient protocol is applicable to a wide range of substrates, including drug intermediates.