Sequential Suzuki–Miyaura Cross-coupling Reactions of 4-Halopyrazolyl MIDA 3-Boronates: A Modular Synthetic Entry to 3,4-Bis(hetero)aromatic Pyrazoles
作者:Thierry Delaunay、Mazen Es-Sayed、Jean-Pierre Vors、Nuno Monteiro、Geneviève Balme
DOI:10.1246/cl.2011.1434
日期:2011.12.5
The 1,3-dipolar cycloaddition of N-arylsydnones with ethynyl MIDA boronate produces mixtures of the corresponding regioisomeric pyrazolyl 3(4)-boronates, with the pyrazolyl 3-boronates predominating by a factor of 7:3. Further C-4 iodination of the latter opened access to 4-iodopyrazolyl MIDA 3-boronates as valuable scaffolds for the elaboration of unsymmetrically 1,3,4-trisubstituted pyrazole derivatives via Suzuki cross-coupling reactions.
N-arylsydnones 与 MIDA 硼酸乙炔酯的 1,3-二极环加成反应产生了相应的 3(4)-吡唑硼酸异构体混合物,其中 3-吡唑硼酸酯以 7:3 的系数占优势。后者的 C-4 进一步碘化,为通过铃木交叉偶联反应制备非对称 1,3,4-三取代的吡唑衍生物提供了 4-碘吡唑 MIDA 3-硼酸酯这一宝贵的支架。