Synthesis of highly functionalized 2,2'-bipyridines by cyclocondensation of β-ketoenamides – scope and limitations
作者:Paul Hommes、Hans-Ulrich Reissig
DOI:10.3762/bjoc.12.112
日期:——
The scope of a flexible route to unsymmetrically functionalized bipyridines is described. Starting from 1,3-diketones 1a-e, the corresponding beta-ketoenamines 2a-e were converted into different beta-ketoenamides 3a-g by N-acylation with 2-pyridinecarboxylic acid derivatives. These beta-ketoenamides were treated with a mixture of TMSOTf and Hunig's base to promote the cyclocondensation to 4-hydroxypyridine
描述了不对称官能化联吡啶的柔性路线的范围。从1,3-二酮1a-e开始,通过用2-吡啶羧酸衍生物进行N-酰化,将相应的β-酮烯胺2a-e转化为不同的β-酮烯酰胺3a-g。将这些β-酮烯酰胺用TMSOTf和Hunig碱的混合物处理,以促进环缩合成4-羟基吡啶衍生物。他们立即采用九氟丁烷磺酰氟进行O-非烧蚀,以中等至良好的总收率提供了预期的4-壬氧基取代的联吡啶衍生物5a-g。如代表性的Suzuki和Sonogashira偶联所证明,联吡啶基壬二酸酯是钯催化反应的出色前体。因此,生成了一个特定取代的联吡啶衍生物的文库,