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Synthesis 2011(2): 199-206
DOI: 10.1055/s-0030-1258373
DOI: 10.1055/s-0030-1258373
PSP
© Georg Thieme Verlag
Stuttgart ˙ New York
2,4-Disubstituted Thiazoles by Regioselective Cross-Coupling or Bromine-Magnesium Exchange Reactions of 2,4-Dibromothiazole
Weitere Informationen
Publikationsverlauf
Received
25 November 2010
Publikationsdatum:
20. Dezember 2010 (online)


Abstract
Cross-coupling reactions occur on 2,4-dibromothiazole preferentially at the more electron-deficient 2-position. This fact can be favorably used to prepare 2-substituted 4-bromothiazoles, which serve as precursors for 2,4-disubstituted thiazoles. Protocols for regioselective Negishi and Stille cross-coupling reactions are provided. Alternatively, the title compound can be metalated in 2-position by a halogen-metal exchange reaction. As a supplement to the well-established bromine-lithium exchange, the regioselective bromine-magnesium exchange reaction is presented.
Key words
catalysis - cross-coupling - heterocycles - palladium - regioselectivity - thiazoles