Formation of <i>N</i>-Alkylpyrroles via Intermolecular Redox Amination

Abstract

A wide variety of aldehydes, ketones, and lactols undergo redox amination when allowed to react with 3-pyrroline in the presence of a mild Brønsted acid catalyst. This reaction utilizes the inherent reducing power of 3-pyrroline to perform the equivalent of a reductive amination to form alkyl pyrroles. In doing so, the reaction avoids stoichiometric reducing agents that are typically associated with reductive aminations. Moreover, the redox amination protocol allows access to alkyl pyrroles that cannot be made via standard reductive amination.