作者:Mark C. Bagley、Christian Glover、Eleanor A. Merritt、Xin Xiong
DOI:10.1055/s-2004-820019
日期:——
5-Bromo-2,6-dialkylpyridine-4-carboxylates are generated in excellent yield by the Michael addition of enaminoesters and ethynyl ketones followed by bromocyclization using N-bromosuccinimide within 1 hour at 0 °C. Treatment of the same aminopentadienone intermediates with N-iodosuccinimide facilitates a low temperature cyclodehydration under very mild conditions to give 2,3,6-trisubstituted pyridines with total regiocontrol.
5-溴-2,6-二烷基吡啶-4-羧酸酯通过酮炔与酰胺酯的迈克尔加成反应生成,随后在0°C下用N-溴琥珀酰亚胺进行溴化环化,收率极高,反应仅需1小时。将相同的氨基五烯酮中间体与N-碘琥珀酰亚胺处理,可在非常温和的条件下促进低温环脱水反应,生成具有完全区域选择性的2,3,6-三取代吡啶。