Topic
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.
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TL;DR: These polymers present the first building blocks towards the design and synthesis of a "universal polymer scaffold" using ring-opening metathesis polymerization (ROMP) of norbornenes.
Abstract: Polymers containing terminal hydrogen-bonding recognition motifs based on diaminotriazine and diaminopyridine groups in their side chains for the self-assembly of appropriate receptors have been prepared by ring-opening metathesis polymerization (ROMP) of norbornenes. A new synthetic method for the preparation of norbornene monomers based on pure alkyl spacers is introduced. These monomers show unprecedented high reactivity using ROMP. To suppress self-association of diaminotriazine-based polymers, polymerizations were run in presence of N-butylthymine. The butylthymine acts as a protecting group via self-assembly onto the hydrogen-bonding sites of the polymeric scaffold, thereby solubilizing the polymer. Diaminopyridine monomers do not require the presence of a protecting group due to their low propensity to dimerize. In addition, they exhibit a high affinity for hydrogen-bonded receptors on both monomeric and polymeric level. These polymers present our first building blocks towards the design and synthesis of a "universal polymer scaffold".
96 citations
TL;DR: A series of homogeneous and heterogeneous palladium(II)-catalysts and their use in Heck-couplings is described in this article, which leads to a significant perturbation of almost perfect square coordination of the corresponding lowereddabilities.
96 citations
TL;DR: In this article, the polymerization of norbornene with two new families of late transition metal-based catalysts derived from: (i) Ni and Pd complexes bearing bulky diammine ligands, with the general formula [ArN=C(R)-C (R)=NAr]MeX 2 and (ii) Fe and Co complexes with bulky arylimine ligands with a general formula [(2,6-ArN =C(Me)) 2 C 5 H 3 N]MX 2]
Abstract: The polymerization of norbornene with two new families of late transition metal-based catalysts derived from: (i) Ni and Pd complexes bearing bulky diammine ligands, with the general formula [ArN=C(R)-C(R)=NAr]MeX 2 and (ii) Fe and Co complexes bearing bulky arylimine ligands with the general formula [(2,6-ArN=C(Me)) 2 C 5 H 3 N]MX 2 is reported. New Co-based complexes have been tested as well. A prevailingly vinylic, amorphous polymer was obtained with all the catalysts tested, whose solubility in organic solvents is substantially dependent on the molucular weight. Polymerization activity greatly varies from one catalyst to another and depends rather on the metal than on the ligand. Solvent polarity and temperature greatly affect the polymerization yields. Besides a dramatic reduction of molecular weights, the addition of small amounts of 1-hexene produces a noticeable increase in the catalytic activity. NMR analysis shows that in all cases a certain percentage of ROMP polymer is present and that, in general, the variations in polymerization conditions, which produce an increase in activity, simultaneously affect a reduction of the ROMP percentage.
96 citations
TL;DR: In this article, a trichlorosilane was used to hydrosilylate norbornene in the presence of palladium catalyst (0.01-0.1 mol %) coordinated with ( R )-MOP ligand, which was oxidized with hydrogen peroxide to give (1 S,2 S,4 R ) -exo -2-norbornanol in 96% ee.
95 citations
TL;DR: In this paper, the mechanism of the alternating ethene/norbornene copolymerisation using [Me 2 C(3- tert BuCp)(Flu)]ZrCl 2 with methylaluminoxane as catalyst is investigated.
Abstract: The mechanism of the alternating ethene/norbornene copolymerisation using [Me 2 C(3- tert BuCp)(Flu)]ZrCl 2 with methylaluminoxane as catalyst is investigated. Copolymerisation models to describe the copolymerisation behavior in the presence of metallocenes with heterotopic sites for monomer coordination are given and applied. It is shown that the microstructure of the copolymers produced at 30°C is the result of a chain migratory insertion mechanism (alternating mechanism) and the sterical hindrance for norbornene insertion at one of the two heterotopic sites of the metallocene. Further investigations on the influence of the reaction parameters showed that an incrcase in temperature (to 60°C) causes deviations from the alternating mechanism.
95 citations