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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: In this paper, a highly efficient metal-free grafting-on strategy based on the cyclopentadiene (Cp)-maleimide click reaction was developed for the preparation of molecular bottlebrushes.
Abstract: A highly efficient metal-free grafting-onto strategy based on the cyclopentadiene (Cp)–maleimide click reaction was developed for the preparation of molecular bottlebrushes (MBBs) with diverse morp...

9 citations

Journal ArticleDOI
TL;DR: Le quadricyclane s'isomerise en norbornadiene dans une matrice de bromure de potassium and d'iodure de cesium.
Abstract: Le quadricyclane s'isomerise en norbornadiene dans une matrice de bromure de potassium et d'iodure de cesium

9 citations

Journal ArticleDOI
TL;DR: In this paper, an estimation of the preferred conformation of diastereomers IIa and IIb with the aid of IR and 1H NMR data, as well as of other physical characteristics of the individual carbinols, has been made.

9 citations

Journal ArticleDOI
TL;DR: In this paper, the chiral 1,5-bisnitrogen ligand 18 and its Rh[(norbornadiene)2] perchlorate complex 25 were studied and the absolute conformation of the chromophore in 18 inverts on binding to Rh(I) in 25.
Abstract: S-α-Methyl-[1-(substituted-phenyl)-2-(2′-pyrido)-1-ethylidene]benzylamines 15–21 and their Rh(I) complexes 22–28 are prepared and their chiroptical and conformational properties are studied. Free ligands are present as enamines in the solution and in the solid state, but are bound to Rh(I) in the imine form. The CD spectra confirm that complexation of 15–21 induces both structural change and strong conformational perturbations. The molecular structures in the crystal are reported for the chiral 1,5-bisnitrogen ligand 18, and its Rh[(norbornadiene)2] perchlorate complex 25. The absolute conformation of the chromophore in 18 inverts on binding to Rh(I) in 25. The value of the torsional angle about C10-C9-C16-C21 bond (−69.7°) in 18, which defines the twisted stilbene-like chromophore, turns for 25 into 75.0°. Chiral S-(−)-methylbenzyl subunit in 18 has a C1-N1-C9-C10 torsional angle of 175.2°, whereas on binding to Rh(I) in 25 this angle changes to −178.4°. The absolute conformation around the styrene-like arrangement of the bonds in 15−21 can be deduced from the strong positive Cotton effect at ca. 350 nm. Cyclopropanation of styrene with ethyl diazoacetate, in the presence of in situ generated Cu(I) complexes of chiral 1,5-bidentate ligands 15–21, yielded cis/trans 2-phenylcyclopropan-1-carboxylic acid ethylesters with 5–21% e.e. Though generally low, the enantioselectivity was somewhat higher for ortho-(16–18) than for para-(19–21) substituted phenyl derivatives.

9 citations

Journal ArticleDOI
TL;DR: Three skeletal rearrangement channels for the norbornadiene to the 1,3,5-cycloheptatriene (CHT*+) radical cation conversion are investigated using the quantum chemical B3LYP, MP2 and CCSD(T) methods in conjunction with the 6-311 +G(d,p) basis set, showing that substitution of particular positions can have dramatic effects on altering reaction barriers in the studied rearrangements.
Abstract: Three skeletal rearrangement channels for the norbornadiene (N˙+) to the 1,3,5-cycloheptatriene (CHT˙+) radical cation conversion, initialized by opening a bridgehead-methylene bond in N˙+, are investigated using the quantum chemical B3LYP, MP2 and CCSD(T) methods in conjunction with the 6–311+G(d,p) basis set. Two of the isomerizations proceed through the norcaradiene radical cation (NCD˙+), either through a concerted path (N˙+ – NCD˙+), or by a stepwise mechanism via a stable intermediate (N˙+ – I1 – NCD˙+). At the CCSD(T)/6–311+G(d,p)//B3LYP/6–311+G(d,p) level, the lowest activation energy, 28.9 kcal mol−1, is found for the concerted path whereas the stepwise path is found to be 2.3 kcal mol−1 higher. On both pathways, NCD˙+ rearranges further to CHT˙+ with significantly less activation energy. The third channel proceeds from N˙+ through I1 and then directly to CHT˙+, with an activation energy of 37.1 kcal mol−1. The multi-step channel reported earlier by our group, which proceeds from N˙+ to CHT˙+via the quadricyclane and the bicyclo[2.2.1]hepta-2-ene-5-yl-7-ylium radical cations, is 4.6 kcal mol−1 lower than the most favorable path of the present study. If the methylene group is substituted with C(CH3)2, however, the concerted path is estimated to be 5.6 kcal mol−1 lower than the corresponding substituted multi-step path at the B3LYP/6–311+(d,p) level. This shows that substitution of particular positions can have dramatic effects on altering reaction barriers in the studied rearrangements. We also note that identical energies are computed for CHT˙+ and NCD˙+ whereas, in earlier theoretical investigations, the former was reported to be 6–17 kcal mol−1 more stable than the latter. Finally, a bent geometry is obtained for CHT˙+ with MP2/6–311+G(d,p) in contradiction with the planar conformation reported for this cation in earlier computational studies.

9 citations


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