Mechanistic Investigation of the Ru-Catalyzed Hydroamidation of Terminal Alkynes

作者：Arndt Matthias; Salih Kifah S M; Fromm Andreas; Goossen Lukas J^*; Menges Fabian; Niedner Schatteburg Gereon

来源：Journal of the American Chemical Society, 2011, 133(19): 7428-7449.

DOI：10.1021/ja111389r

The ruthenium-catalyzed hydroamidation of terminal alkynes has evolved to become a broadly applicable tool for the synthesis of enamides and enimides. Depending on the catalyst system employed, the reaction leads chemo-, regio-, and stereoselectively to a single diastereoisomer. Herein, we present a comprehensive mechanistic study of the ruthenium-catalyzed hydroamidation of terminal alkynes, which includes deuterium-labeling, in situ IR, in situ NMR, and in situ ESI-MS experiments complemented by computational studies. The results support the involvement of ruthenium-hydride and ruthenium-vinylidene species as the key intermediates. They are best explained by a reaction pathway that consists of an oxidative addition of the amide, followed by insertion of a pi-coordinated alkyne into a ruthenium-hydride bond, rearrangement to a vinylidene species, nucleophilic attack of the amide, and finally reductive elimination of the product.

• 出版日期2011-5-18