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Synthesis 2002(16): 2353-2358
DOI: 10.1055/s-2002-35224
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© Georg Thieme Verlag Stuttgart · New York

Regiospecific Allylic Mono- and Dibromination of 4-Methoxy-1,1,1-trihalo-3-alken-2-ones and 5-Methoxy-1,1,1,2,2-pentafluoro-4-hexen-2-one, and their Applications to the Synthesis of Heterocycles

Marcos A. P. Martins*, Adilson P. Sinhorin, Adriano da Rosa, Alex F. C. Flores, Arci D. Wastowski, Claudio M. P. Pereira, Darlene C. Flores, Paulo Beck, Rogerio A. Freitag, Sergio Brondani, Wilson Cunico, Helio G. Bonacorso, Nilo Zanatta
Núcleo de Química de Heterociclos (NUQUIMHE), Departamento de Química, Universidade Federal de Santa Maria, 97, 105-900 Santa Maria, RS, Brazil
Fax: +55(55)2208031; e-Mail: mmartins@base.ufsm.br;
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Publication History

Received 17 June 2002
Publication Date:
04 November 2002 (online)

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Abstract

A series of twelve 5-bromo[5,5-dibromo]-4-methoxy-1,1,1-trihalo-3-alken-2-ones 5a-d, 6a-d, 7a, 9a, 10a and 6-bromo-5-methoxy-1,1,1,2,2-pentafluoro-4-hexen-2-one (8a) were synthesized in high purity and good yields (70-95%) by the regiospecific allylic bromination of 4-methoxy-1,1,1-trihalo-3-alken-2-ones 1a-d, 2a-d, 3a or 5-methoxy-1,1,1,2,2-pentafluoro-4-hexen-2-one (4a), respectively, with bromine followed by addition of pyridine. The usefulness of compounds 5-10 in heterocyclic synthesis is also reported.

Key words

enones - enol ethers - halogens - heterocycles - bromine