2 edition of New heteroatom ligands and metalla-heterocycles via P-N bond formation found in the catalog.
New heteroatom ligands and metalla-heterocycles via P-N bond formation
Tuan Q. Ly
Written in English
Thesis (Ph.D.) - Loughborough University, 1997.
|Statement||by Tuan Q. Ly.|
Metal catalyzed asymmetric allylic alkylation (AAA) reactions have been an extensively studied and fruitful area of research in organic chemistry. The use of heteroatom-centered nucleophiles in this reaction is a powerful method for asymmetric C–X (X = heteroatom) bond formation. This perspective summarizes developments and applications of metal catalyzed AAA reactions employing heteroatom. Stabilized by “carbene” donor ligands, the Pd complex 1 catalyzes the Heck olefination of aryl halides unexpectedly efficiently and yet has long‐term stability at elevated temperatures. The active Pd 0 species can be generated during the Heck reaction or deliberately prepared by reduction of 1 with, for instance, hydrazine or sodium formate.. Another similar catalyst can be synthesized.
15 1,3‐Azoles: Synthesis of imidazoles •From amidines and hydroxy or halocarbonyl compounds Debus‐RadziszewskiRadziszewski imidazole imidazole synthesissynthesis:: diketone and ammonia form an diimine, which condenses with the aldehyde For more imidazole syntheses, look. aryl-oxygen bond formation reactions show that the complexes [Cu(PPh3)3Br] and [Cu(neocup)(PPh3)Br] catalyzed the formation of a range of substituted diphenyl ethers at 20 mol% and 10 mol% catalyst loadings respectively. The polynuclear copper(I) complexes fail to catalyze the same reaction. In aryl-nitrogen bond formation reactions.
The generally accepted mechanism for chelation-assisted C-H bond alkylation is outlined in Scheme l coordination of the transition metal to the chelating heteroatom of 1 followed by facile C-H bond activation provides metallacyclic intermediate iation of a phosphine ligand, followed by olefin binding and hydride insertion, gives 3. 2) If there is more than one heteroatom of the same type numbering starts at the saturated one, e.g. imidazole. 3) If there is more than one type of the heteroatoms, the ring is numbered starting at the heteroatom of the higher priority (O>S>N) and it continues in the direction to give the other heteroatoms the lower numbers as possible.
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This new pathway for C–H bond cleavage would not be productive without accompanying B–C bond formation. Fortunately, this B–C bond formation occurs with a low barrier, presumably because of Cited by: New heteroatom ligands and metalla-heterocycles via P-N bond formation Author: Ly, Tuan Q.
ISNI: Awarding Body: Loughborough University Current Institution: Loughborough University Date of Award: Availability of Full Text: Author: Tuan Q. Another interesting example that combined intramolecular C(sp 2)-H activation with the formation of a new C–N bond was described by Yang's group.
Alkenes 30 in the presence of the combination of Pd II /ligand (in ratio) and O 2 as oxidant yielded indolines 31 in an excellent regioselective manner (Scheme 9).Cited by: Experimental and Theoretical Study on Palladium-Catalyzed C–P Bond Formation via Direct Coupling of Triarylbismuths with P(O)–H Compounds.
The Journal of Organic Chemistry79 (2), DOI: / by: N-Heterocyclic porphyrin hexaphyrin() has been complexed with NpO 2 + to form an inclusion complex. This complex was studied by single crystal X-ray diffraction and the crystal structure is shown in Figure In this complex the neptunium and the nitrogen atoms of the porphyrin are almost perfectly co-planar.
The copper-mediated C(aryl)[bond]N, C(aryl)[bond]O, and C(aryl)[bond]S bond formation is an important transformation and has been developed to include a wide range of substrates. 5 Palladium-Mediated C–X Bond Formation. Transition metals, especially palladium, have been widely used for carbon–heteroatom bond formation reactions including C–O, C–N, C–S, and C–P bonds.
41 Despite efforts in the last decades, only recently have successful transition metal-mediated C–F bond formations been achieved. 42 In this chapter, the general considerations for. NHC (N-heterocyclic carbenes) have evolved to become powerful, universal ligands for the rapid synthesis of novel organometallic complexes.
1 In particular, NHC ligands have found practical use when bound to metals that are know to display high catalytic activity in related organophosphane metal coordination chemistry. 2 Heterocyclic carbenes. The synthesis of several phosphaferrocene-oxazolines, members of a new family of planar-chiral ligands, is described.
These bidentate P,N-ligands are applied to enantioselective palladium-catalyzed allylic alkylations, for which it is shown that the planar-chirality of the phosphaferrocene, not the chirality of the oxazoline, determines the stereochemical outcome of the reaction.
heteroatom are, in general, stable. Those with two heteroatoms are more likely to occur as reactive intermediates. In the case of example 1, cyclization to an oxirane competes with thietane formation, but the greater nucleophilicity of sulfur dominates, especially if a weak base is used.
In example 2 both aziridine and azetidine formation. Title:Synthesis of Aminophosphines and Their Applications in Catalysis VOLUME: 16 ISSUE: 24 Author(s):Valeria A. Stepanova and Irina P. Smoliakova Affiliation:Department of Chemistry, University of North Dakota, Cornell Street, Mail StopGrand Forks, NDUSA.
Keywords:C–P bond formation reactions, P, N-bidentate ligands, Aminophosphines, Ferrocene-based. First published on 18th June Metal catalyzed asymmetric allylic alkylation (AAA) reactions have been an extensively studied and fruitful area of research in organic chemistry.
The use of heteroatom-centered nucleophiles in this reaction is a powerful method for asymmetric C–X (X = heteroatom) bond formation. The structural studies confirm the formulation of new ligands and complexes, and identified bond length trends Pd-N > Pt-N and Pd-E > Pt-E matching earlier reports of isomorphous organometallic complexes of palladium and platinum, but the observed trend Pd-Cl\(_N\).
While several enzymes involved in the N-N bond formation have been identified recently; e.g., CreDEM in cremeomycin biosynthesis 7,8, KtzIT in piperazate biosynthesis 9, and Spb38 and 40 in s Heterocyclic compound - Heterocyclic compound - Major classes of heterocyclic compounds: The major classes of heterocycles containing the common heteroatoms—nitrogen, oxygen, and sulfur—are reviewed in order of increasing ring size, with compounds containing other heteroatoms left to a final section.
Classification by ring size is convenient because heterocyclic rings of a given size have. Synthesis of Saturated Heterocycles via Metal-Catalyzed Alkene Carboamination or Carboalkoxylation Reactions, by John P.
Wolfe Synthesis of Saturated Heterocycles via Metal-Catalyzed Alkene Diamination, Aminoalkoxylation, or Dialkoxylation Reactions, by Sherry R. Chemler Synthesis of. Heterocyclic compound - Heterocyclic compound - Five-membered rings with one heteroatom: The parent aromatic compounds of this family—pyrrole, furan, and thiophene—have the structures shown.
The saturated derivatives are called pyrrolidine, tetrahydrofuran, and thiophane, respectively. The bicyclic compounds made of a pyrrole, furan, or thiophene ring fused to a benzene ring are called. These processes require transition-metal complexes that can both cleave a C–H bond and form a C–heteroatom bond.
Some catalysts, such as iron–oxo complexes, do so without formation of an intermediate containing an M–C bond These complexes often abstract C–H bonds and deliver the resultant hydroxo group to an alkyl radical. Carbon−Heteroatom Bond-Forming Reductive Eliminations of Amines, Ethers, and Sulfides.
Eric R. Strieter, Stephen L. Buchwald, Evidence for the Formation and Structure of Palladacycles during Pd‐Catalyzed C N Bond Formation with Catalysts Derived from Bulky Monophosphinobiaryl Ligands, Angewandte Chemie, /ange,6.
Although organic compounds consist mostly of carbon and hydrogen atoms, strategies for chemical synthesis have traditionally targeted the handful of more reactive interspersed oxygens, nitrogens, and halogens.
Modifying C–H bonds directly is a more appealing approach, but selectivity remains a challenge. Saint-Denis et al. review recent progress in using transition metal catalysis to .The organoborane surrogates that result from hydroboration can be used further for coupling reactions (i.e., formation of new C-C bond or new C-X (heteroatom) bond), which are routinely applied in pharmaceutical development [41,42].Rhodium complexes bearing multidentate nitrogen donor ligands were investigated for their ability to promote alkyne and olefin functionalization reactions.
This thesis work is comprised of two projects in which rhodium-heteroatom reactivity is investigated: P-H bond activation reactions and olefin functionalizations via rhodaoxetane intermediates. [Tp*Rh(PPh3)2] [Tp* = hydrotris(3,5.