Friedländer condensation of 5-aminopyrazole-4-carbaldehydes with reactive α-methylene ketones: Synthesis of pyrazolo[3,4-<i>b</i>]pyridines
作者:Madhukar N. Jachak、Appasaheb B. Avhale、Chanda D. Tantak、Raghunath B. Toche、Claudia Reidlinger、Wolfgang Stadlbauer
DOI:10.1002/jhet.5570420710
日期:2005.11
has been synthesized by Friedlander condensation of 5-arninopyrazole-4-carbaldehydes 3 with α-methylene ketones such as acetone (4a) or acetophenones 4b-f with potassium hydroxide as basic catalyst. Condensation of 5-aminopyrazole-4-carbaldehydes 3 and unsymmetric dialkylketones 6 yielded mixtures of isomeric pyra-zolo[3,4-b]pyridine derivatives 7 and 8. Condensation of 5-aminopyrazole-4-carbaldehydes
通过5-氨基吡唑-4-甲醛3与α-亚甲基酮的弗里德兰德缩合反应,合成了一系列的1,3,6-三取代和1,3,5,6-四取代的吡唑并[3,4- b ]吡啶5。如丙酮(4a)或苯乙酮4b-f,以氢氧化钾为碱性催化剂。5-氨基吡唑-4-甲醛3和不对称二烷基酮6的缩合得到异构的吡唑并[3,4- b ]吡啶衍生物7和8的混合物。5-氨基吡唑-4-甲醛3与CH-酸性酰基乙腈的缩合反应9并以哌啶为碱性催化剂的酰基乙酸酯11得到吡唑并[3,4- b ]吡啶-二-5-甲腈10和吡唑并[3,4- b ]吡啶-5-羧酸酯12。以丙二酸二乙酯13为CH-酸性组分,得到吡唑并[3,4- b ]吡啶-6-酮14。