A direct and operationally simple method for the regioselective synthesis of 2-aryl-substituted 2H-indazoles is reported. The Pd-catalyzed reaction between easily available 2-bromobenzyl bromides and arylhydrazines employing Cs₂CO₃ as the base and t-Bu₃PHBF₄ as the ligand in DMSO at 120 °C in a sealed tube delivers the 2-substituted-2H-indazoles in a single synthetic step with yields up to 79%. The new method is based on a regioselective intermolecular N-benzylation followed by intramolecular N-arylation and oxidation.

中文翻译：

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通过2-卤代苄基卤化物与芳肼之间的钯催化反应直接形成2-取代的2 H-吲唑

报道了直接和操作简单的方法用于区域选择性合成2-芳基取代的2 H-吲唑。容易获得的2-溴苄基溴化物和芳基肼采用铯之间的Pd-催化反应₂ CO ₃作为碱和吨-Bu ₃ PHBF ₄作为在密封管中120℃下在DMSO中配体递送2-取代- 2 ħ -吲唑在单个合成步骤中的收率高达79％。该新方法基于区域选择性的分子间N-苄基化，然后进行分子内N-芳基化和氧化。