title: Air-stable Pd(R-allyl)LCl (L= Q-Phos, P(t-Bu)3, etc.) systems for C-C/N couplings: insight into the structure-activity relationship and catalyst activation pathway.
abstract: A series of Pd(R-allyl)LCl complexes [R = H, 1-Me, 1-Ph, 1-gem-Me(2), 2-Me; L = Q-Phos, P(t-Bu)(3), P(t-Bu)(2)(p-NMe(2)C(6)H(4)), P(t-Bu)(2)Np] have been synthesized and evaluated in the Buchwald-Hartwig aminations in detail, in addition to the preliminary studies on Suzuki coupling and α-arylation reactions. Pd(crotyl)Q-PhosCl (9) was found to be a superior catalyst to the other Q-Phos-based catalysts, and the reported in situ systems, in model coupling reactions involving 4-bromoanisole substrate with either N-methylaniline or 4-tert-butylbenzeneboronic acid. Precatalyst 9 also performed better than the catalysts bearing P(t-Bu)(2)(p-NMe(2)C(6)H(4)) ligand; however, it is comparable to the new crotyl catalysts bearing P(t-Bu)(3) or P(t-Bu)(2)Np ligands. In α-arylation of a biologically important model substrate, 1-tetralone, Pd(allyl)P(t-Bu)(2)(p-NMe(2)C(6)H(4))Cl (15) was found to be the best catalyst. The reason for the relatively higher activity of the crotyl complexes in comparison to the allyl derivatives in C-N bond formation reactions was investigated using X-ray crystallography in conjunction with NMR spectroscopic studies.
authors.affiliation: Johnson Matthey Catalysis & Chiral Technologies, Orchard Road, Royston, SG8 5HE, UK.
authors.forename: Carin C C
authors.initials: CC
authors.lastname: Johansson Seechurn
authors.forename: Sébastien L
authors.initials: SL
authors.lastname: Parisel
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Colacot
mesh_terms: D000388:Air; D000586:Amination; D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D008958:Models, Molecular; D008968:Molecular Conformation; D009584:Nitrogen / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D010165:Palladium / Q000737:chemistry*; D013329:Structure-Activity Relationship; D013696:Temperature
chemical_list: D009942:Organometallic Compounds; D010165:Palladium; D002244:Carbon; D009584:Nitrogen