Open AccessSelective Manganese-Catalyzed Dimerization and Cross-Coupling of Terminal Alkynes
Author(s) -
Stefan Weber,
Luı́s F. Veiros,
Karl Kirchner
Publication year - 2021
Publication title -
acs catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.898
H-Index - 198
ISSN - 2155-5435
DOI - 10.1021/acscatal.1c01137
Subject(s) - catalysis , alkyne , acetylide , chemistry , manganese , alkyl , triple bond , yield (engineering) , bond cleavage , ligand (biochemistry) , medicinal chemistry , polymer chemistry , photochemistry , combinatorial chemistry , organic chemistry , double bond , materials science , biochemistry , receptor , metallurgy
Herein, efficient manganese-catalyzed dimerization of terminal alkynes to afford 1,3-enynes is described. This reaction is atom economic, implementing an inexpensive, earth-abundant nonprecious metal catalyst. The precatalyst is the bench-stable alkyl bisphosphine Mn(I) complex fac- [Mn(dippe)(CO) 3 (CH 2 CH 2 CH 3 )]. The catalytic process is initiated by migratory insertion of a CO ligand into the Mn-alkyl bond to yield an acyl intermediate that undergoes rapid C-H bond cleavage of alkyne, forming an active Mn(I) acetylide catalyst [Mn(dippe)(CO) 2 (C≡CPh)(η 2 -HC≡CPh)] together with liberated butanal. A range of aromatic and aliphatic terminal alkynes were efficiently and selectively converted into head-to-head Z -1,3-enynes and head-to-tail gem -1,3-enynes, respectively, in good to excellent yields. Moreover, cross-coupling of aromatic and aliphatic alkynes selectively yields head-to-tail gem -1,3-enynes. In all cases, the reactions were performed at 70 °C with a catalyst loading of 1-2 mol %. A mechanism based on density functional theory (DFT) calculations is presented.