Regioselective formylation of pyrazolo[3,4-b]pyridine and pyrazolo[1,5-a]pyrimidine systems using Vilsmeier–Haack conditions
作者:Jairo Quiroga、Jorge Trilleras、Braulio Insuasty、Rodrigo Abonía、Manuel Nogueras、Justo Cobo
DOI:10.1016/j.tetlet.2008.02.166
日期:2008.4
Regioselective formylation behavior has been found in the reaction of pyrazolo[3,4-b]pyridines and pyrazolo[1,5-a]pyrimidines via Vilsmeier–Haack conditions. While the 4,5- and 6,7-dihydro derivatives afforded pyrazolo[3,4-b]pyridine-5-carbaldehydes and 4,7-dihydropyrazolo[1,5-a]pyrimidine-3,6-dicarbaldehydes, respectively, the aromatic analogs rendered the pyrazolo[1,5-a]pyrimidine-3-carbaldehyde
吡唑并[3,4- b ]吡啶和吡唑并[1,5- a ]嘧啶通过Vilsmeier-Haack条件的反应中发现了区域选择性的甲酰化行为。虽然4,5-和6,7-二氢衍生物分别提供了吡唑并[3,4- b ]吡啶5-甲醛和4,7-二氢吡唑并[1,5 - a ]嘧啶3,6-二甲醛。芳族类似物仅产生吡唑并[1,5 - a ]嘧啶-3-甲醛,吡唑并吡啶衍生物没有反应。