64103-00-0Relevant articles and documents
Transition-state stabilization by a secondary substrate-ligand interaction: A new design principle for highly efficient transition-metal catalysis
Smejkal, Tomas,Gribkov, Denis,Geier, Jens,Keller, Manfred,Breit, Bernhard
supporting information; experimental part, p. 2470 - 2478 (2010/06/17)
A library of monodentate phosphane ligands, each bearing a guanidine receptor unit for carboxylates, was designed. Screening of the library gave some excellent catalysts for regioselective hydroformylation of ss,γ- unsaturated carboxylic acids. A terminal alkene, but-3-enoic acid, was hydroformylated with a linear/branched (l/b) regioselectivity up to 41. An internal alkene, pent-3-enoic acid was hydroformylated with regioselectivity up to 18:1. Further substrate selectivity (e.g., acid vs. methyl ester) and reaction site selectivity (monofunctionalization of 2- vinylhept-2-enoic acid) were also achieved. Exploration of the structure-activity relationship and a practical and theoretical mechanistic study gave us an insight into the nature of the supramolecular guanidinium-carboxylate interaction within the catalytic system. This allowed us to identify a selective transition-state stabilization by a secondary substrate-ligand interaction as the basis for catalyst activity and selectivity.
