Addition of amines and phenols to acrylonitrile derivatives catalyzed by the POCOP-type pincer complex [{κ P,κ C,κ P-2,6-( i-Pr 2PO) 2C 6H 3}Ni(NCMe)][OSO 2CF 3

Abstract

The pincer-type complex [{κ P ,κ C ,κ P -2,6-( i-Pr 2PO) 2C 6H 3}Ni(NCMe)][OSO 2CF 3] ( 1) can serve as a precatalyst for the regioselective, anti-Markovnikov addition of nucleophiles to activated olefins. The catalyzed additions of aliphatic amines to acrylonitrile, methacrylonitrile, and crotonitrile proceed at room temperature and give quantitative yields of products resulting from the formation of C–N bonds. On the other hand, aromatic amines or alcohols are completely inert toward methacrylonitrile and crotonitrile, and much less reactive toward acrylonitrile, requiring added base, heating, and extended reaction times to give good yields. The catalytic reactivities of 1 are thought to arise from the substitutional lability of the coordinated acetonitrile that allows competitive coordination of the nitrile moiety in the olefinic substrates; this binding enhances the electrophilicity of the C C moiety, rendering them more susceptible to attack by nucleophiles. In some cases, RCN → Ni binding results in double bond isomerization/migration (allyl cyanide) or attack of nucleophiles at the nitrile moiety (cinnamonitrile and 4-cyanostyrene). Reaction of morpholine with 1 at 60 °C led to formation of the amidine derivative 2 that has been characterized by X-ray crystallography.