Nickel(II)/Lewis acid catalysed olefin hydroamination and hydroarylation under mild conditions.

Aniline derivatives are important nitrogen-containing compounds with wide applications in chemicals, pharmaceuticals and agrochemicals. In the work described herein, nickel(II)/Lewis acid (LA) catalysed olefin hydroamination with anilines was explored for use in aniline derivative syntheses. The Ni(II)/LA catalysis proceeded smoothly under mild conditions, whereas using Ni(OAc) 2 alone, the catalyst was inactive. Remarkably, the Markovnikov addition type products were obtained when substituted styrenes were used as the olefin source, while the anti-Markovnikov addition type products were obtained when the electron-deficient olefins such as acrylonitrile and acrylates were used. The mechanistic studies revealed that hydroamination of the styrene derivates proceeded via the amino-Ni(II)/LA attacking the carbocation intermediate which was generated by the protonation of the olefin, whereas for acrylonitrile and acrylates, it proceeded by a direct amino-Ni(II)/LA attack on the olefin by nucleophilic addition. In addition, the hydroarylation product was generated by the Hofmann-Martius rearrangement of the hydroamination product.