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

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
› Author Affiliations
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.


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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