ESI-MS detection of proposed reaction intermediates in the air-promoted and ligand-modulated oxidative Heck reaction.
Electrospray ionization mass spectrometry (ESI-MS) and subsequent MS/MS analyses were used to directly detect palladium-containing cationic reaction intermediates in a ligand controlled palladium(II)-catalyzed oxidative Heck arylation. All potential intermediates were observed as dmphen-ligated palladium(II) species, suggesting that the dmphen bidentate ligand is attached to the metal center during the entire catalytic cycle. The study supports previous mechanistic propositions and provides new information regarding the composition of aryl-containing Pd(II) complexes in an ongoing oxidative Heck reaction. In addition, sodium acetate was found to be a useful base alternative to previously used tertiary amines.
Enquist
Per-Anders
PA
Organic Pharmaceutical Chemistry, Department of Medicinal Chemistry, Uppsala Biomedical Center, Uppsala University, P. O. Box 574, SE-751 23 Uppsala, Sweden.
Nilsson
Peter
P
Sjöberg
Per
P
Larhed
Mats
M
D000388:Air; D001555:Benzene Derivatives / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D006868:Hydrolysis; D007659:Ketones / Q000138:chemical synthesis* / Q000737:chemistry; D008024:Ligands; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010084:Oxidation-Reduction; D010165:Palladium / Q000737:chemistry*; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013237:Stereoisomerism; D053719:Tandem Mass Spectrometry / Q000379:methods
D001555:Benzene Derivatives; D007659:Ketones; D008024:Ligands; D009942:Organometallic Compounds; D010165:Palladium