Nucleophilic ortho-Allylation of Pyrroles and Pyrazoles: An Accelerated Pummerer/Thio-Claisen Rearrangement Sequence
摘要:
Arylsulfinyl groups direct the metal-free, regiospecific, nucleophilic ortho-allylation of pyrroles and pyrazoles. Mechanistic studies support the intermediacy of allylsulfonium salts that undergo facile thio-Claisen rearrangement onto the heterocyclic ring, giving products of coupling. The strategy has been adapted to allow regiospecific propargylation of the heterocyclic substrates.
已经通过氮和硫亲核试剂与芳基碘化物和溴化物的交叉偶联反应研究了D-氨基葡萄糖的C–N和C–S键的形成。咪唑,苯并咪唑,吲哚,吡咯烷和二苯基二硫化物在10摩尔%D-葡萄糖胺,10摩尔%CuI和2当量的存在下与芳基卤化物发生反应。DMSO–H 2中的Cs 2 CO 3浓度在中等温度下O可得到相应的产物,收率良好至极佳。具有卤化物,游离氨基,三氟甲基和杂环的底物具有良好的耐受性。配体的高水溶性使其易于去除催化剂。此外,使用市售底物也成功证明了该催化体系在尼罗替尼中间体合成中的应用。