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Transition‐State Stabilization by a Secondary Substrate–Ligand Interaction: A New Design Principle for Highly Efficient Transition‐Metal Catalysis
Author(s) -
Šmejkal Tomáš,
Gribkov Denis,
Geier Jens,
Keller Manfred,
Breit Bernhard
Publication year - 2010
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200902553
Subject(s) - regioselectivity , chemistry , selectivity , hydroformylation , catalysis , alkene , ligand (biochemistry) , carboxylate , transition metal , substrate (aquarium) , denticity , combinatorial chemistry , carboxylic acid , supramolecular chemistry , stereochemistry , organic chemistry , metal , rhodium , molecule , biochemistry , oceanography , receptor , geology
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 β,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.