Thomas Schareina

Bis(pyrimidine)-based palladium catalysts: synthesis, X-ray structure and applications in Heck–, Suzuki–, Sonogashira–Hagihara couplings and amination reactions

Abstract The synthesis of N,N-bis(pyrimid-2-yl)amine (1), N-acetyl-N,N-bis(pyrimid-2-yl)amide (2), N-norborn-2-ene-5-ylbis(pyrimid-2-yl)carbamide (4) is described. The Pd-complex N-acetyl-N,N-bis(pyrimid-2-yl)amine palladium dichloride (3) has been prepared from compound 2 and its X-ray structure has been determined. A polymer supported catalytic system (6) was prepared via ring-opening metathesis copolymerization of 4 with 1,4,4a,5,8,8a-hexahydro-1,4,5,8-exo-endo-dimethanonaphthalene (HDMN-6) and subsequent loading with PdCl2. Both the homogeneous and heterogeneous catalysts 3 and 6 were active in Heck–, Suzuki–, Sonogashira–Hagihara-type couplings and amination reactions using aryl iodides, bromides and chlorides.

N-Acyl-N,N-dipyridyl and N-acyl-N-pyridyl-N-quinoyl amine based palladium complexes. Synthesis, X-ray structures, heterogenization and use in Heck couplings

A series of homogeneous and heterogeneous palladium(II)-catalysts and their use in Heck-couplings is described. Starting from four different amines, N -pyrid-2-yl- N -(3-methylpyrid-2-yl)amine ( 1 ), N -pyrid-2-yl- N -(6-methylpyrid-2-yl)amine ( 2 ), N -(6-methylpyrid-2-yl)- N -(4-methylquinolin-2-yl)amine ( 3 ) and N -bis(6-methylpyrid-2-yl)amine ( 4 ), the corresponding acetyl- and norbornene derivatives, N -pyrid-2-yl- N -(3-methylpyrid-2-yl) acetamide ( 5 ), N -pyrid-2-yl- N -(6-methylpyrid-2-yl) acetamide ( 6 ), N -(6-methylpyrid-2-yl)- N -(4-methylquinolin-2-yl) acetamide ( 7 ), N -bis(6-methylpyrid-2-yl)acetamide ( 8 ) and N -pyrid-2-yl- N -(3-methylpyrid-2-yl)- endo -norborn-2-ene-5-carbamide ( 9 ), N -pyrid-2-yl- N -(6-methylpyrid-2-yl)- endo -norborn-2-ene-5-carbamide ( 10 ) and N -(6-methylpyrid-2-yl)- N -(4-methylquinolin-2-yl)- endo -norborn-2-ene-5-carbamide ( 11 ), respectively, have been prepared. The acetyl derivatives 5 – 8 have been used for the preparation of the homogeneous Heck catalysts N -acetyl- N -pyrid-2-yl- N -(3-methylpyrid-2-yl)amine palladium dichloride ( 13 ), N -acetyl- N -pyrid-2-yl- N -(6-methylpyrid-2-yl)amine palladium dichloride ( 14 ), N -acetyl- N -(6-methylpyrid-2-yl)- N -(4-methylquinolin-2-yl)amine palladium dichloride ( 15 ) and N -acetyl- N -bis(6-methylpyrid-2-yl)amine palladium dichloride ( 16 ). X-ray data were obtained for compounds 9 , 11 , 13 and 14 . Polymer supports 17 – 19 were prepared via ring-opening metathesis copolymerization of the norbornene derivatives 9 – 11 with 1,4,4a,5,8,8a-hexahydro-1,4,5,8- exo - endo -dimethano-naphthalene (HDMN-6) and subsequently loaded with palladium(II) chloride. Both the homogeneous catalysts 13 – 16 and the heterogeneous catalysts are active in the vinylation of aryl iodides and aryl bromides with turn-over numbers (TONs) of up to 220 000. Comparably low yields (=34%) and TONs (=2100) are achieved in the tetrabutylammonium bromide- (TBAB-) assisted vinylation of aryl chlorides as well as in the amination of aryl bromides. Structural data of compounds 9 , 11 , 13 and 14 were compared with those of the parent systems, N -acetyldipyridylamine palladiumdichloride ( 20 ) and the poly( N , N -dipyrid-2-yl- endo -norborn-2-ene-5-carbamide)based resin ( 21 ), respectively. Thus, methyl-substitution leads to a significant perturbation of the almost perfect square planar coordination of Pd found in 20 resulting in lowered stabilities of the corresponding Pd-complexes 13 – 16 and consequently lowered coupling yields compared to 20 and 21 .

Dipyridylamine Ligands − Synthesis, Coordination Chemistry of the Group 10 Metals and Application of Nickel Complexes in Ethylene Oligomerization

A great variety of 2,2′-bipyridylamines can be synthesized starting from primary amines or 2-aminopyridines (for instance, symmetrically and unsymmetrically substituted as well as chiral ligands) by palladium-catalyzed aryl amination. The reaction of such ligands with [PdCl2(COD)] or [NiBr2(DME)] (COD = cycloocta-1,5-diene; DME = 1,2-dimethoxyethane) led to the corresponding dichloro or dibromo complexes. The results of X-ray crystal structure analyses of selected compounds show that the ligands coordinate through the two pyridine N-atoms. Their palladium complexes have a slightly distorted planar coordination (in the case of nickel a distorted tetrahedral coordination), with N−M−N angles of 96.0(2)° (M = Ni) and 85.7° (averaged, M = Pd). The nickel complexes are highly active ethylene oligomerization catalysts if activated with Et3Al2Cl3.

Coordination Polymers of Bipyridyldicarboxylates – a Cobalt Containing 12,3‐net with Potential Reactive Sites

The porous cobalt(II) coordination polymer [Co{2,2′-bipy-4,4′(CO2)2}(H2O)2] (1) was prepared via a hydrothermal synthesis approach starting from Co(NO3)2 · 6 H2O and 2,2′-bipyridine-4,4′-dicarboxylic acid in a one to one mixture of ethanol and water at 120 °C. The product was characterized by single crystal X-ray diffraction, TGA and elemental analysis. Space group: P3121, unit cell dimensions at –73 °C: a = 11.980(2), c = 8.335(2) A, R = 0.032, wR2 (all data) = 0.048. The structure determination revealed 1 to be a network in which octahedrally coordinated cobalt atoms are arranged to form a (12,3) net.

Crystalline Materials with Large Channels or Cavities – Synthesis and Crystal Structure of an Iron(III) tetra(4‐carboxyphenyl)‐porphine

Tetra(4-carboxyphenyl)-porphine iron(III) chloride · 2 CH3COOH · 4 H2O (1) was prepared via a hydrothermal synthesis approach starting from FeCl2 and 5,10,15,20-tetrakis-(4-carboxyphenyl)-21 H,23 H-porphine in glacial acetic acid in the presence of KOH as a base and ytterbium(III) acetate as a template. Compound 1 was characterized by single crystal X-ray diffraction and elemental analysis. Space group: P 1, Z = 2, unit cell dimensions at 200 K: a = 9.282(2), b = 20.239(5), c = 22.239(5) A, α = 92.49(3), β = 99.87(3), γ = 90.78(3)°, R1 (observed) = 0.132, wR2 (all data) = 0.395. The architecture of the structure is determined by interporphyrin hydrogen bonding. Four iron porphyrin units form a very wide open channel with dimensions of circa 15.7 A × 15.7 A. No interpenetrating is observed.

Polymerized ionic amphiphiles: Synthesis and effects in the enantioselective hydrogenation of an amino acid precursor

A number of polymerizable ionic amphiphiles has been polymerized in water at various concentrations above their critical micelle concentration (cmc). Oligomeric and polymeric species are formed upon photochemical initiation. Depending on the position of the double bond within the monomer and polymerization conditions (temperature, concentration, use of radical starters) polymeric assemblies were obtained of different size and hence water-solubility. After separation of low-molecular components by dialysis water-soluble polymers have been characterized by their molecular weights (membrane and vapor pressure osmometry) and transmission electron microscopy (TEM). They showed different efficiency as promotors in the rhodium complex-catalyzed asymmetric hydrogenation of (Z)-methyl α-acetamidocinnamate in water and have been compared with their monomeric counterparts. As was demonstrated in one case, associates formed by intramicellar polymerization display an enhanced catalytic efficiency whereas clustered assemblies are inactive.