A three step procedure for the synthesis of 6-substituted 4-hydroxy-2-pyrones 2 from aldehydes 1 is described. An acetoacetate equivalent 3 was added to the corresponding aldehyde (10 examples) in a vinylogous Mukaiyama aldol addition (72-99%). The intermediate alcohols 4 were oxidized to the ketones 5 using the Dess-Martin method (67%-quant.). A final thermal cyclization of compounds 5 yielded the title compounds 2 (61-92%; 40-85% overall).
描述了一种从醛1合成6-取代的
4-羟基-2-
吡喃酮2的三步程序。向相应的醛中加入了一种
乙酰乙酸酯等效物3(10个例子)进行维尼洛戈斯Mukaiyama aldol加成(72-99%)。中间醇4通过Dess-Martin方法被氧化为酮5(67%-量)。最后对化合物5进行热环化反应,得到了目标化合物2(61-92%;整体转换率为40-85%)。