2-(3-Bromophenyl)-2H-1,2,3-triazole is a low molecular-weight building block that is not readily accessible in pure form by standard synthetic approaches due to competing formation of the triazol-1-yl regioisomer. After investigation of a wide range of synthetic routes, a process based on construction of the triazole heterocycle by cyclization of an activated dihydrazone was developed. A suitable isolation method had to be identified before embarking on a demonstration run on >100 g scale without the need for chromatography. The new process delivered the desired building block in 48 % overall yield over four telescoped steps with excellent purity (99 % a/a).

中文翻译：

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通过 N−N 键形成环化可扩展、无需色谱法合成 2-(3-溴苯基)-2H-1,2,3-三唑

2-(3-溴苯基)-2 H -1,2,3-三唑是一种低分子量结构单元，由于三唑-1-基区域异构体的竞争形成，不易通过标准合成方法以纯形式获得。在研究了多种合成路线后，开发了一种基于通过活化二腙环化构建三唑杂环的方法。在开始 >100 g 规模的演示运行（无需色谱法）之前，必须确定合适的分离方法。新工艺通过四个叠接步骤以 48% 的总收率交付了所需的构建模块，并具有出色的纯度 (99% a/a)。