Norbornene

About: Norbornene is a research topic. Over the lifetime, 5628 publications have been published within this topic receiving 104495 citations. The topic is also known as: norbornylene & norcamphene.

Iron(III) aroylhydrazone complexes: Structure, electrochemical studies and catalytic activity in oxidation of olefins

Abstract: Tridentate Schiff base ligands derived from aromatic aldehydes and benzhydrazide, and their iron complexes [Fe(L1)(HL1)] 1, [Fe(HL1)Cl2(CH3OH)]·(CH3OH) 2 and [Fe(HL2)Cl2(H2O)] 3 have been prepared and characterized (H2L1 = (E)-N′-(2-hydroxy-3-methoxybenzylidene)benzohydrazide, H2L2 = (E)-N′-(5-bromo-2-hydroxybenzylidene)benzohydrazide). The crystal structure of 2 has been determined. The electrochemical properties of these complexes have been investigated by cyclic voltammetric technique in acetonitrile solutions. Electrochemical studies have revealed quasi-reversibility for these compounds. The catalytic potential of these complexes has been tested for the oxidation of cyclooctene using tert-butylhydroperoxide (TBHP) as oxidant. The effects of the molar ratio of oxidant to substrate, the temperature, the co-catalyst concentration and the solvent have been studied. Excellent selectivities have been obtained for the epoxidation of cyclohexene, cyclooctene, norbornene, cis- and trans-stilbene.

Benchmarking of ruthenium initiators for the ROMP of a norbornenedicarboxylic acid ester

Abstract: The kinetic study of ring-opening metathesis polymerization (ROMP) of a diester functionalised norbornene derivative, (±)-exo,endo-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid diethyl ester, with a series of ruthenium benzylidene complexes revealed the applicability of these initiators for well defined polymerization reactions. Values for the rate of initiation as well as the rate of propagation of the initiators were determined and correlated to the molecular weight and polydispersity of the isolated polymers. As the only initiator providing an entry to virtually monodisperse polymers the classical “first generation Grubbs-catalyst” was identified, while N-heterocyclic carbene based initiators polymerized with a rate of propagation much higher than the rate of initiation yielding polymers with a broader molecular weight distribution.

Norbornene-constrained cyclic peptides with hairpin architecture: design, synthesis, conformation, and membrane ion transport

Abstract: A novel family of hairpin cyclic peptides has been designed on the basis of the use of norbornene units as the bridging ligands. The design is flexible with respect to the choice of an amino acid, the ring size, and the nature of the second bridging ligand as illustrated here with the preparation of a large number of norborneno cyclic peptides containing a variety of amino acids in ring sizes varying from 12- to 29-membered, with the choice of the second bridging ligand being a rigid norbornene (11, 13a,b), an adamantane unit (7a,b and 8), or a flexible cystine residue (4a,b and 10). The presence of built-in handles (as protected COOH groups) permits the attachment of a variety of subunits as shown here with the ligation of Leu-Leu, Val-Val, or Aib-Aib pendants in 4b, 7b, and 13b, respectively. This novel class of constrained cyclic peptides are demonstrated to adopt beta-sheet- or hairpin-like conformation as shown by (1)H NMR and CD spectra. Membrane ion-transport studies have shown that the norborneno cyclic peptides 4b and 7b containing Leu-Leu or Val-Val pendants symmetrically placed on the exterior of the ring show high efficiency and selectivity in the transport of specifically monovalent cations. This property can be attributed to the hairpin-like architecture induced by the norbornene unit since the bis-adamantano peptide 15 containing two pairs of Leu-Leu pendants on the exterior is able to transport both monovalent (Na(+), K(+)) and divalent (Mg(2+)/Ca(2+)) cations.