Issue 7, 2015

Carbene catalyzed umpolung of α,β-enals: a reactivity study of diamino dienols vs. azolium enolates, and the characterization of advanced reaction intermediates

Abstract

Since their discovery by Bode and Glorius in 2004, N-heterocyclic carbene catalyzed conjugate umpolung reactions of α,β-enals have been postulated to involve the formation of diamino dienols (“homoenolates”) and/or azolium enolates (“enolates”), typically followed by addition to electrophiles, e.g. Michael-acceptors. In this article, we provide evidence, for the first time, for the postulated individual and specific reactivity patterns of diamino dienols (γ-C–C-bond formation) vs. azolium enolates (β-C–C-bond formation). Our study is based on the pre-formation of well defined diamino dienols and azolium enolates, and the in situ NMR monitoring of their reactivities towards enone electrophiles. Additionally, reaction intermediates were isolated and characterized, inter alia by X-ray crystallography.

Graphical abstract: Carbene catalyzed umpolung of α,β-enals: a reactivity study of diamino dienols vs. azolium enolates, and the characterization of advanced reaction intermediates

Supplementary files

Article information

Article type
Edge Article
Submitted
21 Mar 2015
Accepted
30 Apr 2015
First published
30 Apr 2015
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2015,6, 3706-3711

Author version available

Carbene catalyzed umpolung of α,β-enals: a reactivity study of diamino dienols vs. azolium enolates, and the characterization of advanced reaction intermediates

V. R. Yatham, Jörg-M. Neudörfl, N. E. Schlörer and A. Berkessel, Chem. Sci., 2015, 6, 3706 DOI: 10.1039/C5SC01027F

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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