We report the selective functionalization of the 1H-imidazo[1,2-b]pyrazole scaffold using a Br/Mg-exchange, as well as regioselective magnesiations and zincations with TMP-bases (TMP = 2,2,6,6-tetramethylpiperidyl), followed by trapping reactions with various electrophiles. In addition, we report a fragmentation of the pyrazole ring, giving access to push–pull dyes with a proaromatic (1,3-dihydro-2H-imidazol-2-ylidene)malononitrile core. These functionalization methods were used in the synthesis of an isostere of the indolyl drug pruvanserin. Comparative assays between the original drug and the isostere showed that a substitution of the indole ring with a 1H-imidazo[1,2-b]pyrazole results in a significantly improved solubility in aqueous media.

中文翻译：

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1H-咪唑并[1,2-b]吡唑支架的选择性功能化。吲哚的一种新的潜在非经典等排体和推拉染料的前体

我们报告了 1 H-咪唑并[1,2- b ]吡唑支架的选择性官能化使用 Br/Mg 交换，以及区域选择性氧化和 TMP 碱（TMP = 2,2,6,6-四甲基哌啶基），然后与各种亲电子试剂发生捕获反应。此外，我们报告了吡唑环的断裂，从而获得了具有前芳香族（1,3-二氢-2 H-咪唑-2-亚基）丙二腈核的推拉染料。这些功能化方法用于合成吲哚基药物普万色林的等排体。原始药物和等排体之间的比较分析表明，吲哚环被 1 H -咪唑并[1,2- b]吡唑显着提高了在水性介质中的溶解度。