Cu(I)-Catalyzed Cross-Coupling Rearrangements of Terminal Alkynes with Tropylium Tetrafluoroborate: Facile Access to Barbaralyl-Substituted Allenyl Acid Esters and 7‑Alkynyl Cycloheptatrienes

• Published in: Journal of organic chemistry Vol. 87; no. 5; pp. 3066 - 3078
• Main Authors: Fan, Zhe, Ni, Shao-Fei, Pang, Jin-Yu, Guo, Li-Ting, Yang, Hao, Li, Ke, Ma, Cheng, Liu, Ji-Kai, Wu, Bin, Yang, Jin-Ming
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 04.03.2022; Amer Chemical Soc
• Subjects: alkynes; carbenes; Chemistry; Chemistry, Organic; cross-coupling reactions; organic chemistry; Physical Sciences; Science & Technology; GOLD; PROPARGYLIC ESTERS; YNAMIDES; GENERATION; ENANTIOSELECTIVE SYNTHESIS; CARBENES
• ISSN: 0022-3263; 1520-6904; 1520-6904
• DOI: 10.1021/acs.joc.1c02849

Herein, we report a novel strategy for the formation of copper carbene via the cycloisomerization of the π-alkyne–Cu­(I) complex from terminal alkynes and tropylium tetrafluoroborate. Mechanistic studies and DFT calculations indicate that the reaction undergoes the intramolecular cycloisomerization process from the π-alkyne–Cu­(I) complex to afford the copper carbene intermediate, followed by migratory insertion with the second terminal alkyne to afford the barbaralyl-substituted allenyl acid esters. In addition, we develop a mild and highly efficient Cu­(I)-catalyzed cross-coupling protocol to synthesize 7-alkynyl cycloheptatrienes that has a broad functional group tolerance and is applicable to the late-stage functionalization of natural products.