title: Platinum-based catalysts for the hydroamination of olefins with sulfonamides and weakly basic anilines.
abstract: Electrophilic Pt(II) complexes catalyze efficient hydroaminations of olefins by sulfonamides and weakly basic anilines. Catalysts include the structurally characterized complex (COD)Pt(OTf)2 (1) and the known dimer [PtCl2(C2H4)]2, activated by AgBF4. Experiments with substituted anilines establish an empirical pKa cutoff (conjugate acid pKa < 1) for the participation of nitrogen-containing substrates in this catalysis. Arylsulfonamides (conjugate acid pKa approximately -6) with various para substituents hydroaminate olefins such as cyclohexene in yields greater than 95% at 90 degrees C. Hydroamination of propylene by p-toluenesulfonamide proceeds with Markovnikov selectivity, suggesting a mechanism that involves olefin activation at Pt. With norbornene and p-toluenesulfonamide as the substrates and 1 as the catalyst, intermediate [(COD)Pt(norbornene)2][OTf]2 (3) was identified and characterized by 19F and 195Pt NMR spectroscopies and mass spectrometry. Kinetic studies provide the empirical rate law, rate = k(obs)[Pt][sulfonamide], and are consistent with a mechanism in which attack of a sulfonamide on the Pt-coordinated olefin is the rate-determining step.
authors.affiliation: Department of Chemistry and Chemical Engineering, University of California, Berkeley, Berkeley, California 94720, USA.
authors.forename: Dmitry
authors.initials: D
authors.lastname: Karshtedt
authors.forename: Alexis T
authors.initials: AT
authors.lastname: Bell
authors.forename: T Don
authors.initials: TD
authors.lastname: Tilley
mesh_terms: D000475:Alkenes / Q000138:chemical synthesis / Q000737:chemistry*; D000586:Amination; D000814:Aniline Compounds / Q000737:chemistry*; D002384:Catalysis; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D010984:Platinum / Q000737:chemistry*; D013449:Sulfonamides / Q000737:chemistry*
chemical_list: D000475:Alkenes; D000814:Aniline Compounds; D009942:Organometallic Compounds; D013449:Sulfonamides; D010984:Platinum; C023650:aniline