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Synthesis of Bench-Stable N-Quaternized Ketene N,O-Acetals and Preliminary Evaluation as Reagents in Organic Synthesis

preprint
submitted on 24.07.2019 and posted on 26.07.2019 by Alisha M. Blades, Danielle L. McConnell, Danielle Gomes Rodrigues, Phoebe V. Keyes, Justin C. Sonberg, Caitlin E. Anthony, Sofia Rachad, Olivia M. Simone, Caroline F. Sullivan, Jonathan D. Shapiro, Christopher C. Williams, Benjamin C. Schafer, Jack A. Goodman, Max Majireck
N-Quaternized ketene N,O-acetals are typically an unstable, transient class of compounds most commonly observed as reactive intermediates. In this report, we describe a general approach to a variety of benchstable N-quaternized ketene N,O-acetals via treatment of pyridine or aniline bases with ethoxyacetylene and an appropriate Brønsted or Lewis acid (triflic acid, triflimide, or scandium(III) triflate). The resulting pyridinium and anilinium salts may be used as reagents or synthetic intermediates in multiple reaction types. For example, N-(1-ethoxyvinyl) pyridinium or anilinium salts can thermally release highly reactive O-ethyl ketenium ions that undergo electrophilic aromatic substitution with electron rich arenes. N-(1-ethoxyvinyl)-2-halopyridinium salts can also be utilized in peptide couplings as a derivative of Mukaiyama reagents, or react with alcohol and amines in nucleophilic aromatic substitutions.

Funding

Edward and Virginia Taylor Fund

History

Email Address of Submitting Author

mmajirec@hamilton.edu

Institution

Hamilton College

Country

USA

ORCID For Submitting Author

0000-0002-0400-6982

Declaration of Conflict of Interest

No conflict of Interest

Version Notes

Preliminary draft.

Exports