Synthesis of Isoxazole- and Oxazole-4-carboxylic Acids Derivatives by Controlled Isoxazole-Azirine-Isoxazole/Oxazole Isomerization
作者:Anna V. Serebryannikova、Ekaterina E. Galenko、Mikhail S. Novikov、Alexander F. Khlebnikov
DOI:10.1021/acs.joc.9b02536
日期:2019.12.6
The first synthesis of isoxazole-4-carboxylic acid derivatives by domino isoxazole-isoxazole isomerization is reported. Fe(II)-catalyzed isomerization of 4-acyl-5-methoxy-/5-aminoisoxazoles (dioxane, 105 °C) leads to the formation of isoxazole-4-carboxylic esters and amides in good yields. 4-Formyl-5-methoxyisoxazoles give methyl oxazole-4-carboxylates under the same reaction conditions. Fe(II)-catalyzed
报道了通过多米诺骨牌异恶唑-异恶唑异构化的首次合成异恶唑-4-羧酸衍生物。Fe(II)催化的4-酰基-5-甲氧基-/ 5-氨基异恶唑(二恶烷,105°C)的异构化导致形成高收率的异恶唑-4-羧酸酯和酰胺。在相同的反应条件下,4-甲酰基-5-甲氧基异恶唑生成恶唑-4-羧酸甲酯。Fe(II)在较温和的条件下(MeCN,50°C)催化4-酰基-5-甲氧基异恶唑的异构化反应可以制备瞬时的2-酰基-2-(甲氧基羰基)-2H-叠氮基。在催化条件下(二恶烷,105°C)或在非催化热解条件下(邻二氯苯,170°C),叠氮化物定量异构化为异恶唑。