Synthesis 2023; 55(13): 2083-2090
DOI: 10.1055/a-2017-4685
paper
Special Issue dedicated to Prof. Alain Krief

A Mild Method for the Replacement of a Hydroxyl Group by Halogen: 4. Practical Synthesis of Cyclic β-Halovinylketones under Neutral Conditions

Authors

  • François Munyemana

    a   UCLouvain, Place L. Pasteur, 1, 1348 Louvain-la-Neuve, Belgium
    b   Department of Chemistry, Eduardo Mondlane University, Av. Julius Nyerere Nr 3453, PO Box 257, Maputo, Mozambique
  • Léon Ghosez

    a   UCLouvain, Place L. Pasteur, 1, 1348 Louvain-la-Neuve, Belgium
    c   European Institute of Chemistry and Biology (IECB), Univ. Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248 2, rue Robert Escarpit, 33607, Pessac, France

We are grateful to the Administration Générale de la Coopération au Développement (AGCD) for providing a Ph.D. fellowship to F.M. We also thank the Belgian Federal Science Policy Office, Belgian Federal Government (SPPS, action concertée 86-91-84), Ciba-Geigy (Basel) and UCLouvain for support.


Graphical Abstract

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With admiration and friendship to Prof. Alain Krief on the occasion of his 80th birthday.

Abstract

The replacement of a hydroxyl group by a halogen is a pivotal organic functional group transformation. Existing procedures often require acidic conditions or lack sustainability and atom economy. We have previously shown that tetramethyl-α-haloenamines (TMXE) or 2,2-dimethyl-1-halo-1-diisopropylamines (DIXE) react with a wide variety of hydroxyl-containing molecules to yield the corresponding halides under very mild conditions and with high atom economy. We now show that the deoxyhalogenation reactions of the enol tautomers of cyclic1,3-diketones and of 2-hydroxymethylene cycloketones can also be performed with TMCE or DIXE to yield β-halo-α,β-unsaturated ketones in excellent yields. The reactions are regioselective and in some cases stereoselective. The reaction is also successful with acetylacetone but the yield is only moderate. β-Ketoesters are not reactive. The method favorably compares to the best existing methods: It is more general, occurs under very mild conditions, which should allow acid-sensitive functional groups such as ketals, esters, ethers, etc., to be tolerated, and, above all, is quite sustainable (no toxic reagents or products).



Publication History

Received: 21 November 2022

Accepted after revision: 22 January 2023

Accepted Manuscript online:
22 January 2023

Article published online:
02 March 2023

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