TY - JOUR
T1 - Ruthenium Carboxylate Complexes as Efficient Catalysts for the Addition of Carboxylic Acids to Propargylic Alcohols
AU - Jeschke, Janine
AU - Gaebler, Christian
AU - Korb, Marcus
AU - Rueffer, Tobias
AU - Lang, Heinrich
PY - 2015/6
Y1 - 2015/6
N2 - Ruthenium complexes [Ru(CO)(2)(PPh3)(2)(O2CR)(2)] - 3a (R = CH2OCH3), 3b (R = iPr), 3c (R = tBu), 3d (R = 2-(C4H3O)-C-c), and 3e (R = Ph) - were synthesized by treatment of Ru(CO)(3)(PPh3)(2) with the corresponding carboxylic acids. The molecular structures of the newly synthesized complexes in the solid state are discussed. Compounds 3a-e were successfully applied as catalysts in the addition of carboxylic acids to propargylic alcohols to give the corresponding -oxo esters in good to excellent yields even in air. The different carboxylate ligands do not have an influence on the productivities, because the carboxylates exchange rapidly under the applied reaction conditions, as was confirmed by P-31{H-1} NMR spectroscopic studies. The addition of catalytic amounts of Na2CO3 resulted in an increase in -oxo ester formation. The reaction is tolerant to the use of versatile functional groups on the propargylic alcohols and carboxylic acids, revealing a broad substrate generality. In contrast to most other known catalytic systems, even sterically hindered substrates, including 2,4,6-trimethylbenzoic acid, 1,1-diphenylprop-2-yn-1-ol, or the biologically active steroid ethisterone, were successfully converted.
AB - Ruthenium complexes [Ru(CO)(2)(PPh3)(2)(O2CR)(2)] - 3a (R = CH2OCH3), 3b (R = iPr), 3c (R = tBu), 3d (R = 2-(C4H3O)-C-c), and 3e (R = Ph) - were synthesized by treatment of Ru(CO)(3)(PPh3)(2) with the corresponding carboxylic acids. The molecular structures of the newly synthesized complexes in the solid state are discussed. Compounds 3a-e were successfully applied as catalysts in the addition of carboxylic acids to propargylic alcohols to give the corresponding -oxo esters in good to excellent yields even in air. The different carboxylate ligands do not have an influence on the productivities, because the carboxylates exchange rapidly under the applied reaction conditions, as was confirmed by P-31{H-1} NMR spectroscopic studies. The addition of catalytic amounts of Na2CO3 resulted in an increase in -oxo ester formation. The reaction is tolerant to the use of versatile functional groups on the propargylic alcohols and carboxylic acids, revealing a broad substrate generality. In contrast to most other known catalytic systems, even sterically hindered substrates, including 2,4,6-trimethylbenzoic acid, 1,1-diphenylprop-2-yn-1-ol, or the biologically active steroid ethisterone, were successfully converted.
KW - Synthetic methods
KW - Homogeneous catalysis
KW - Ruthenium
KW - Propargylic alcohols
KW - SAWHORSE-TYPE COMPLEXES
KW - RAY CRYSTAL-STRUCTURE
KW - DER-WAALS RADII
KW - STRUCTURAL-CHARACTERIZATION
KW - POLYNUCLEAR COMPOUNDS
KW - FORMIC-ACID
KW - ESTERS
KW - DERIVATIVES
KW - LIGANDS
KW - VAN
U2 - 10.1002/ejic.201500203
DO - 10.1002/ejic.201500203
M3 - Article
SN - 1434-1948
SP - 2939
EP - 2947
JO - European Journal of Inorganic Chemistry
JF - European Journal of Inorganic Chemistry
IS - 18
ER -