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Synthesis 2002(15): 2220-2224
DOI: 10.1055/s-2002-34854
PAPER
© Georg Thieme Verlag Stuttgart · New York

A Convenient Preparation of 4-Methyl- and 4-Phenylseleno-1,1,1-trihalo-3-
alken-2-ones and their Usefulness in the Synthesis of 3-Trihalomethyl­isoselenazoles

Marcos A. P. Martins*, Giovani P. Bastos, Adilson P. Sinhorin, Nilo E. K. Zimmermann, 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 28 February 2002
Publication Date:
21 October 2002 (online)

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Abstract

A convenient synthesis of fourteen 4-methyl- and 4-phenylseleno-1,1,1-trihalo-3-alken-2-ones [CX3C(O)CH=CR1SeR, where X = F, Cl; R = Me, Ph; and R1 = H, alkyl, aryl] from the reaction of the corresponding 4-methoxy-1,1,1-trihalo-3-alken-2-ones with methyl- or phenylselenols in the presence of boron tri­fluoride etherate is reported. The reaction of 4-methylseleno-1,1,1-trihalo-3-alken-2-ones with bromine and ammonia lead to 3-trihalomethylisoselenazoles in good yields. The usefulness of the trichloromethyl group as a carboxyl group precursor was demonstrated by the conversion of 5-ethyl-3-trichloromethylisoselenazole to 5-ethyl-3-carboxyisoselenazole acid.

Key words

isoselenazoles - selenium - enones - halogens - heterocycles