Cu-Catalyzed Alkylative Carboxylation of Ynamides with Dialkylzinc Reagents and Carbon Dioxide.
Alkylative carboxylation of ynamides with CO2 and dialkylzinc reagents using a N-heterocyclic carbene (NHC)-copper catalyst has been developed. A variety of ynamides, both cyclic and acyclic, undergo this transformation under mild conditions to afford the corresponding α,β-unsaturated carboxylic acids, which contain the α,β-dehydroamino acid skeleton. The present alkylative carboxylation formally consists of Cu-catalyzed carbozincation of ynamides with dialkylzinc reagents with the subsequent nucleophilic carboxylation of the resulting alkenylzinc species with CO2 . Dialkylzinc reagents bearing a β-hydrogen atom such as Et2 Zn and Bu2 Zn still afford the alkylated products despite the potential for β-hydride elimination. This protocol would be a desirable method for the synthesis of highly substituted α,β- dehydroamino acid derivatives due to its high regio- and stereoselectivity, simple one-pot procedure, and its use of CO2 as a starting material.
Advanced Catalysis Research Group, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan).|Organometallic Chemistry Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan).
Masanori
M
Takimoto
Advanced Catalysis Research Group, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan).|Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8570 (Japan).
Sandeep Suryabhan
SS
Gholap
Advanced Catalysis Research Group, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan). houz@riken.jp.|Organometallic Chemistry Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan). houz@riken.jp.|Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8570 (Japan). houz@riken.jp.
Zhaomin
Z
Hou
carbon dioxide; carboxylation; copper; ynamides; zinc