4.4 Amination of Nitriles
Zargarian and co-workers reported the amination of nitriles with primary or secondary amines to the amidines, catalysed by nickel pincer complexes. The reaction was
initially discovered as an unwanted side reaction in the Michael addition of amines to
cinnamonitrile [84]. More recently, together with French colleagues, they developed
a new series of PCP ligands having an imidazolium group as part of the ligand
backbone [94]. Bis-cationic complex 55 catalysed the addition of piperidine,
morpholine or hexylamine to acetonitrile or benzonitrile with moderate to good
yields (Table 17). Use of primary amines led to the formation of mixtures of the Nmono-substituted and the N,N
0 -disubstituted amidines. Use of a 4:1 mixture of
primary amine and nitrile led to the sole production of the disubstituted product.
Arnold had previously shown that the Ni PNP complex 56 catalysed the addition of
piperidine to acetonitrile with 5 mol% of catalyst at room temperature to give 68%
yield of the amidine (Scheme 52) [95].
Table 17 PCP pincer complex-catalysed amination of nitriles
Catalytic Conversion of Nitriles by Metal Pincer Complexes
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