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Norbornadiene

About: Norbornadiene is a research topic. Over the lifetime, 2389 publications have been published within this topic receiving 38603 citations.


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Journal ArticleDOI
TL;DR: The intermolecular Pauson-Khand reaction (PKR), a carbonylative cycloaddition between an alkyne and an alkene, is a convenient method to prepare cyclopentenones and two possible nonadiabatic pathways for the photochemical rearrangement arise.
Abstract: The intermolecular Pauson-Khand reaction (PKR), a carbonylative cycloaddition between an alkyne and an alkene, is a convenient method to prepare cyclopentenones. Using norbornadiene as alkene, a myriad of tricyclo[5.2.1.0(2,6)]deca-4,8-dien-3-ones 1 can be easily prepared. The mechanism of the photochemical rearrangement of these adducts 1 into tricyclo[5.2.1.0(2,6)]deca-3,8-dien-10-ones 2 has been studied. The ground state (S(0)) and the three lowest excited states ((3)(pi pi*), (1)(n pi*), and (3)(n pi*)) potential energy surfaces (PESs) concerning the prototypical rearrangement of 1a (the cycloadduct of the PK carbonylative cycloaddition of norbornadiene and ethyne) to 2a have been thoroughly explored by means of CASSCF and CASPT2 calculations. From this study, two possible nonadiabatic pathways for the photochemical rearrangement arise: one starting on the (3)(pi pi*) PES and the other on the (1)(n pi*) PES. Both involve initial C-C gamma-bond cleavage of the enone, which leads to the formation of a bis-allyl or an allyl-butadienyloxyl diradical, respectively, that then decays to the S(0) PES through a (3)(pi pi*)/S(0) surface crossing or a (1)(n pi*)/S(0) conical intersection, each one lying in the vicinity of the corresponding diradical minimum. Once on the S(0) PES, the ring-closure to 2a occurs with virtually no energy barrier. The viability of both pathways was experimentally studied by means of triplet sensitization and quenching studies on the photorearrangement of the substituted Pauson-Khand cycloadduct 1b (R = TMS, R' = H) to 2b. Using high concentrations of either piperylene as a triplet quencher, or benzophenone as a triplet sensitizer, the reaction rate significantly slowed down. A Stern-Volmer type plot of product 2b concentration vs triplet quencher concentration showed an excellent linear correlation, thus indicating that only one excited state is involved in the photorearrangement. We conclude that, though there is a nonadiabatic pathway starting on the (1)(n pi*) PES, the reaction product is formed through the (3)(pi pi*) state because the energy barrier involved in the initial C-C gamma-bond cleavage of the enone is much lower in the (3)(pi pi*) PES than in the (1)(n pi*) PES.

3 citations

Journal ArticleDOI
TL;DR: The trifluoromethylenaminoketones, with a strained cyclobutene and norbornadiene moieties, were firstly prepared from the corresponding β-halogeno-α,β-unsaturated triflumineto-β-ketones in almost quantitative yields.

3 citations

Patent
03 Jun 1997
TL;DR: In this paper, the bis(5-vinyl-norbornyl) sulfide represented by the formula is obtained by reacting (B) norbornene or an unsaturated compound having a nor-bornene skeleton with (C) hydrogen sulfide in (A) an amino compound and/or a polar solvent having >=3 debye (D) dipole moment and >=30 relative permittivity.
Abstract: PROBLEM TO BE SOLVED: To produce a new compound useful as a plasticizer, etc., and further a cocross-linking agent, etc., for an optical resin material, a rubber material, etc. SOLUTION: This bis(5-vinyl-norbornyl) sulfide represented by the formula. A bisnorbornyl sulfide compound including the compound represented by the formula is obtained by reacting (B) norbornene or an unsaturated compound having a norbornene skeleton (preferably any of norbornadiene, vinylidenenorbornene, ethylidenenorbornene and dicyclopentadiene) with (C) hydrogen sulfide in (A) an amino compound and/or a polar solvent having >=3 debye (D) dipole moment and >=30 relative permittivity. One kind selected from dimethylformamide, dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, etc., is preferred as the polar solvent of the component (A). Furthermore, the compound represented by the formula is obtained by using 5-vinyl-2-norbornene as the component (B).

3 citations

Journal ArticleDOI
TL;DR: The first chelate ever of 1,6-diphospha-1,5-hexadiene, IV, was obtained by X-ray crystallography.

3 citations

Journal ArticleDOI
TL;DR: In this paper, the cyclodimerization of norbornadiene-2,5 (NBD) is studied in the presence of a catalytic system based on bis(η3-allyl)nickel.
Abstract: Kinetics of the cyclodimerization of norbornadiene-2,5 (NBD) is studied in the presence of a catalytic system based on bis(η3-allyl)nickel. The forms of the rate laws characterized by different reaction orders with respect to NBD are determined. The influence of temperature and solvent nature on the process is studied. The thermodynamic parameters are determined. The structure of the products is shown to be determined by the structure of intermediates. The mechanism of the process, consisting of the following main steps, is proposed: (1) the formation of Ni(NBD)2, which is the true catalyst; (2) the reversible addition of NBD to the indicated complex, resulting in the formation of Ni(NBD)3 and Ni(NBD)4 η-complexes and accompanied by a change in ligand coordination; (3) the oxidative addition of coordinated NBD molecules to a nickel atom that gives five and six-membered metallacyclic intermediates; and (4) the reductive elimination of nickel from them to form cyclic dimers. The conditions for the selective formation of individual isomers are proposed.

3 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202316
202240
202133
202040
201930
201829