CC BY-ND-NC 4.0 · Synthesis 2019; 51(05): 1157-1170
DOI: 10.1055/s-0037-1611634
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Metal Enolates – Enamines – Enol Ethers: How Do Enolate Equivalents Differ in Nucleophilic Reactivity?

Artem I. Leonov
,
Daria S. Timofeeva
,
Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstraße 5–13, 81377 München, Germany   Email: ofial@lmu.de   Email: Herbert.mayr@cup.lmu.de
,
Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstraße 5–13, 81377 München, Germany   Email: ofial@lmu.de   Email: Herbert.mayr@cup.lmu.de
› Author Affiliations
Deutsche Forschungsgemeinschaft (SFB 749, project B1).
Further Information

Publication History

Received: 23 November 2018

Accepted after revision: 27 November 2018

Publication Date:
08 January 2019 (online)

A contribution of Physical Organic Chemistry to systematizing Organic Synthesis. Cordial congratulations on the occasion of the Golden Anniversary of Synthesis.

Published as part of the 50 Years SYNTHESISGolden Anniversary Issue

Abstract

The kinetics of the reactions of trimethylsilyl enol ethers and enamines (derived from deoxybenzoin, indane-1-one, and α-tetralone) with reference electrophiles (p-quinone methides, benzhydrylium and indolylbenzylium ions) were measured by conventional and stopped-flow photometry in acetonitrile at 20 °C. The resulting second-order rate constants were subjected to a least-squares minimization based on the correlation equation lg k = s N(N + E) for determining the reactivity descriptors N and s N of the silyl enol ethers and enamines. The relative reactivities of structurally analogous silyl enol ethers, enamines, and enolate anions towards carbon-centered electrophiles are determined as 1, 107, and 1014, respectively. A survey of synthetic applications of enolate ions and their synthetic equivalents shows that their behavior can be properly described by their nucleophilicity parameters, which therefore can be used for designing novel synthetic transformations.

Supporting Information

 
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