Nucleophilic attack of α-aminoalkyl radicals on carbon-nitrogen triple bonds to construct α-amino nitriles: an experimental and computational study.

A new reactivity pattern of α-aminoalkyl radicals, involving nucleophilic attack on C≡N triple bonds under thermal conditions, has been developed to construct α-amino nitriles. In contrast to previous C-H functionalization of tertiary amines involving α-aminoalkyl radicals, this methodology does not require the use of photocatalytic conditions or a transition-metal catalyst. Inexpensive and nontoxic phenylacetonitrile was chosen as cyano source for this α-aminonitrile forming reaction. A plausible mechanism is proposed based upon experimental and computational results. An α-aminoalkyl radical intermediate and benzoyl cyanide have been shown to be key intermediates in this green and mild radical process. Nucleophilic attack of the α-aminoalkyl radical on the C≡N bond of PhCOCN followed by an elimination step forms the desired α-aminonitrile and an acyl radical.