Redox-Neutral α-Oxygenation of Amines: Reaction Development and Elucidation of the Mechanism
Open Access
- 1 April 2014
- journal article
- research article
- Published by American Chemical Society (ACS) in Journal of the American Chemical Society
- Vol. 136 (16), 6123-6135
- https://doi.org/10.1021/ja501988b
Abstract
Cyclic secondary amines and 2-hydroxybenzaldehydes or related ketones react to furnish benzo[e][1,3]oxazine structures in generally good yields. This overall redox-neutral amine α-C–H functionalization features a combined reductive N-alkylation/oxidative α-functionalization and is catalyzed by acetic acid. In contrast to previous reports, no external oxidants or metal catalysts are required. Reactions performed under modified conditions lead to an apparent reductive amination and the formation of o-hydroxybenzylamines in a process that involves the oxidation of a second equivalent of amine. A detailed computational study employing density functional theory compares different mechanistic pathways and is used to explain the observed experimental findings. Furthermore, these results also reveal the origin of the catalytic efficiency of acetic acid in these transformations.Keywords
Funding Information
- National Science Foundation (OCI-1053575)
- National Science Foundation (CHE-1059084)
- National Institute of General Medical Sciences (R01GM101389-01)
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