“Iron-Catalyzed Intramolecular Allylic C-H Amination” Paradine, S. M.; White, M. C. J. Am. Chem. Soc. 2012, 134, 2036-2039. DOI: 10.1021/ja211600g
In their recent communication, Christina White’s group at Illinois reports a new allylic C-H amination catalyzed by iron. This builds on previous work from their group in Pd sulfoxide catalyzed allylic amination and iron catalyzed C-H oxidation. In addition to showcasing an exciting reaction, this paper is a great contribution from a green chemistry perspective: they use a cheap, non-toxic metal catalyst to do a highly selective C-H oxidation reaction, one that streamlines the synthesis of C-N bonds directly from the (relatively) unreactive C-H bond. Interestingly, quantitative comparisons are made throughout the paper to the more commonly used Rh2(OAc)4 catalyst.
They start by screening Fe catalysts for intramolecular allylic amination reactivity of sulfamate substrates. Although the polypyridyl Fe complex they have used previously for hydroxylation and desaturation chemistry gave a low yield of product, the phthalocyanine Fe complex 1 gave a good yield (and better than a tetraphenylporphyrin iron complex) of allylic amination. Importantly, they obtained only trace quantities of the aziridination product, showing the high selectivity of the iron-catalyzed reaction (>20:1).