由叠氮化钠原位形成的叠氮酸的铜催化叠氮-炔环加成得到 4-单取代-1,2,3-三唑,The Journal of Organic Chemistry

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由叠氮化钠原位形成的叠氮酸的铜催化叠氮-炔环加成得到 4-单取代-1,2,3-三唑
The Journal of Organic Chemistry ( IF 3.3 ) Pub Date : 2022-02-11 , DOI: 10.1021/acs.joc.1c02775
Dominik Jankovič ₁ , Miha Virant ₁ , Martin Gazvoda ₁

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我们报道了铜催化叠氮化氢（叠氮酸，HN ₃ ）与末端炔烃的环加成反应，以可持续的方式形成4-取代-1 H -1,2,3-三唑。在酸性条件下，叠氮化钠原位形成叠氮酸，在铜催化反应中与末端炔烃反应。使用多齿N-供体螯合配体和温和的有机酸，在甲醇-水混合物中，在有氧条件下，在催化剂负载量为5 mol%的情况下，反应在室温下进行，得到4-取代的-1,2,3-三唑在高产量中。该方法适用于多种炔底物，包括未受保护的肽，显示出不同的官能团耐受性。它适用于后期功能化合成策略，如氯沙坦三唑类似物的合成所示。实现了从Fmoc- 1-炔丙基甘氨酸制备正交保护的氮杂组氨酸的克级规模。叠氮酸的危险性已经降低，因为它在原位形成，浓度<6%，可以安全处理。叠氮酸蒸馏溶液的反应表明其在铜催化反应中作为活性物质的作用。

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Copper-Catalyzed Azide–Alkyne Cycloaddition of Hydrazoic Acid Formed In Situ from Sodium Azide Affords 4-Monosubstituted-1,2,3-Triazoles

We report a copper-catalyzed cycloaddition of hydrogen azide (hydrazoic acid, HN₃) with terminal alkynes to form 4-substituted-1H-1,2,3-triazoles in a sustainable manner. Hydrazoic acid was formed in situ from sodium azide under acidic conditions to react with terminal alkynes in a copper-catalyzed reaction. Using polydentate N-donor chelating ligands and mild organic acids, the reactions were realized to proceed at room temperature under aerobic conditions in a methanol–water mixture and with 5 mol % catalyst loadings to afford 4-substituted-1,2,3-triazoles in high yields. This method is amenable on a wide range of alkyne substrates, including unprotected peptides, showing diverse functional group tolerance. It is applicable for late-stage functionalization synthetic strategies, as demonstrated in the synthesis of the triazole analogue of losartan. The preparation of orthogonally protected azahistidine from Fmoc-l-propargylglycine was realized on a gram scale. The hazardous nature of hydrazoic acid has been diminished as it forms in situ in <6% concentrations at which it is safe to handle. Reactions of distilled solutions of hydrazoic acid indicated its role as a reactive species in the copper-catalyzed reaction.

更新日期：2022-02-11

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