Conformational preferences and enantiodiscrimination of phosphino-4-(1-hydroxyalkyl)oxazoline-metal-olefin complexes resulting from an OH-metal hydrogen bond.
[reaction: see text] Phosphinooxazolines carrying (1-hydroxy-1-phenyl)methyl and (1-methoxy-1-phenyl)methyl substituents in the 4 position of the oxazoline ring exhibit contrasting behavior in Pd- and Ir-catalyzed allylic alkylations. Whereas catalysts with the methoxy-containing ligand generally provide products with high ee's, use of catalysts prepared from the hydroxy-containing ligand results in products with low ee's or even racemates. DFT calculations suggest the presence of a hydrogen bond with Pd(0) as the proton acceptor in the hydroxy-containing olefin-Pd(0) complexes, which induces a conformational change in the ligand, leading to different stereoselectivity.
Frölander
Anders
A
Department of Chemistry, Organic Chemistry, Royal Institute of Technology, SE 100 44 Stockholm, Sweden.
Lutsenko
Serghey
S
Privalov
Timofei
T
Moberg
Christina
C
D000475:Alkenes / Q000737:chemistry*; D000478:Alkylation; D000498:Allyl Compounds / Q000138:chemical synthesis / Q000737:chemistry; D002384:Catalysis; D006860:Hydrogen Bonding; D006878:Hydroxides / Q000737:chemistry*; D007495:Iridium / Q000737:chemistry*; D008024:Ligands; D008956:Models, Chemical; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010080:Oxazoles / Q000138:chemical synthesis / Q000737:chemistry*; D010984:Platinum / Q000737:chemistry*; D013237:Stereoisomerism
D000475:Alkenes; D000498:Allyl Compounds; D006878:Hydroxides; D008024:Ligands; D009942:Organometallic Compounds; D010080:Oxazoles; D007495:Iridium; D010984:Platinum; C031356:hydroxide ion