Copper-Catalyzed Alkynylation of <i>In Situ</i>-Generated Azoalkenes: An Umpolung Approach to Pyrazoles

Авторы: Kokuev Aleksandr O., Sukhorukov Alexey Yu
Журнал: Organic Letters
Том: 26
Номер: 33
Год издания: 2024
Издательство: American Chemical Society
Местоположение издательства: United States
Первая страница: 6999
Последняя страница: 7003
DOI: 10.1021/acs.orglett.4c02471
Аннотация: A straightforward umpolung approach to regioselectively N-protected polysubstituted pyrazoles starting from aromatic α-halohydrazones and terminal alkynes has been developed. In this process, azoalkenes generated in situ from α-halohydrazones are involved in the Cu(I)-catalyzed Michael addition with alkynes to give α-alkynyl-substituted hydrazones that cyclize to give the target pyrazoles in 37–85% yield. The method employs readily available starting materials and features good functional group compatibility (nitro, sulfonyl, cyano, trimethylsilyl, and primary bromoalkyl groups, esters, and alcohols are tolerated) and scalability.
Добавил в систему: Сухоруков Алексей Юрьевич

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