吡唑并[1,5-a]吡嗪的第 7 位官能化

IF 2 Q2 CHEMISTRY, ORGANIC
SynOpen Pub Date : 2024-07-01 DOI:10.1055/s-0043-1775378
Georgyi Koidan, Nazar Tsyzoryk, Eduard B. Rusanov, Svitlana V. Shishkina, Mykhailo Vovk, Aleksandr Kostyuk
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引用次数: 0

摘要

我们报告了吡唑并[1,5-a]吡嗪衍生物在 2、3、4 位上的直接甲酰化反应。由于硅基的 1,2 迁移,N,N,N′,1,1,1-六甲基硅烷甲脒与其碳烯形式处于平衡状态。随后产生的碳烯可以插入吡唑并[1,5-a]吡嗪类化合物中酸性最强的 C-H 基团。计算得出的最酸性 pKa(DMSO)C-H 基团位于第 7 位,与取代基的关系不大。反应以高产率进行,生成的氨基化合物可水解为相应的醛。对这些氨基化合物进行甲醇分解可得到相应的甲基亚胺。通过对一组衍生物进行 X 射线晶体结构分析,明确地证明了氨基化合物的结构。这种方法非常简单,通常甚至不需要溶剂,而且可以扩展到其他杂环化合物。
本文章由计算机程序翻译,如有差异,请以英文原文为准。

Functionalization of Position 7 of Pyrazolo[1,5-a]pyrazines

Functionalization of Position 7 of Pyrazolo[1,5-a]pyrazines

We report a straightforward formylation at position 7 of pyrazolo[1,5-a]pyrazine derivatives featuring substituents at the 2,3,4 positions. N,N,N′,1,1,1-Hexamethylsilanecarboximidamide exists in equilibrium with its carbene form due to 1,2-migration of the silyl group. The ensuing carbene can be inserted into the most acidic C–H group of the pyrazolo[1,5-a]pyrazines. The most acidic calculated pK a (DMSO) C–H group is at position 7 and does not depend significantly on the substituents. The reactions proceed in high yields affording aminals that can be hydrolyzed to the corresponding aldehydes. Methanolysis of the aminals affords the corresponding methylimines. The constitution of the aminals was unambiguously proved by X-ray crystal structure analysis of a set of derivatives. The method is simple, often does not require even solvents, and can be extended to other heterocyclic compounds.

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来源期刊
SynOpen
SynOpen CHEMISTRY, ORGANIC-
CiteScore
2.30
自引率
4.00%
发文量
35
审稿时长
6 weeks
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