NIS-Mediated intermolecular hydroamination of allenamides with imidazole heterocycles: a facile protocol for the synthesis of allylic N,N-acetals?

New Journal of Chemistry Pub Date: 2018-09-21 DOI: 10.1039/C8NJ03641A

Abstract

Allylic N,N-acetals are important intermediates in the synthesis of biologically active heterocycles and natural products. Herein, we report a facile protocol for the synthesis of this compound through N-iodosuccinimide-mediated hydroamination of allenamides by imidazole heterocycles. The reaction is regioselective, fast, and tolerant of a broad scope of imidazole and benzimidazole derivatives. The key intermediate is a conjugated sulfimide ion species that undergoes nucleophilic attack by imidazole to form the 1,2-adduct. Mixtures of N1- and N3-substituted isomers were obtained using asymmetrically substituted imidazoles. However, the 1,4-adduct was obtained using a tri-substituted imidazole. The efficiency of the gram-scale reaction suggests the potential industrial application of this synthetic method.

Graphical abstract: NIS-Mediated intermolecular hydroamination of allenamides with imidazole heterocycles: a facile protocol for the synthesis of allylic N,N-acetals
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