2,4-Disubstituted Thiazoles by Regioselective Cross-Coupling or Bromine-Magnesium Exchange Reactions of 2,4-Dibromothiazole
作者:Thorsten Bach、Stefan Gross、Stefan Heuser、Carolin Ammer、Golo Heckmann
DOI:10.1055/s-0030-1258373
日期:2011.1
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.
2,4-二溴噻唑的交叉偶联反应优先发生在更缺电子的 2 位。这一事实可用于制备 2-取代的 4-溴噻唑,作为 2,4-二取代噻唑的前体。本研究提供了区域选择性 Negishi 和 Stille 交叉偶联反应的方案。另外,还可以通过卤素-金属交换反应将标题化合物 2 位金属化。作为对成熟的溴-锂交换反应的补充,介绍了具有区域选择性的溴-镁交换反应。