The Rh-TPPTS complex was heterogenized onto layered double hydroxides (LDH) Zn
3AlCl and Co
2FeCO
3 using ion-exchange procedure. Before ion exchange, the Rh precursor Rh(cod)Cl
2 was dissolved ...together with the TPPTS ligand in deionised water and stirred for 12
h. After stirring, the LDH was added to the solution and stirred for another 24
h, then filtered, washed with deionised water, and dried under vacuum at room temperature for 16
h. The characterization of the catalysts was carried out using several techniques: ICP-AES, N
2 adsorption–desorption isotherms at −196
°C, thermal analysis, powder X-ray diffraction, XPS and DRIFTs. Substrates were prepared via Diels–Alder reaction of various 2
H-pyran-2-ones with
N-substituted maleimides in an aqueous medium with microwave irradiation. The catalytic tests were performed in a stirred stainless-steel autoclave using H
2 pressures in the range 20–40
atm, 30
mg catalyst and 30
mg substrate, at different temperatures. Hydrogenation of bicyclo2.2.2octenes showed that these strained and functionalized cycloadducts were inert to classic catalysts but could be hydrogenated by using ionic-immobilized Rh-ligand complexes on the LDH. The Rh-TPPTS/Zn
3AlCl was found to exhibit a pretty high activity and selectivity for such reactions leading to heteropolycyclic derivatives. The heterogeneous catalyst was easily recycled with no leaching.
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An efficient new method was developed for the preparation of vinyl & divinyl diketones through gold catalyzed oxidation of 1,3-enynes and 1,5-dien-3-ynes. Synthetic application of ...these vinyl & divinyl diketones were also explored, in which, dicarbonyl bicyclo2.2.2octenes & bicyclo2.2.1heptenes, vinyl quinoxalines and 2-amino pyrrole derivatives were synthesized.
The syntheses and crystal structures of the two title compounds, C
11
H
10
O
3
(
I
) and C
17
H
14
BrNO
2
(
II
), both containing the bicyclo2.2.2octene ring system, are reported here the structure ...of
I
has been reported previously: White & Goh (2014). Private Communication (refcode HOKRIK). CCDC, Cambridge, England. The bond lengths and angles of the bicyclo2.2.2octene ring system are similar for both structures. The imide functional group of
II
features carbonyl C=O bond lengths of 1.209 (2) and 1.210 (2) Å, with C—N bond lengths of 1.393 (2) and 1.397 (2) Å. The five-membered imide ring is nearly planar, and it is positioned
exo
relative to the alkene bridgehead carbon atoms of the bicyclo2.2.2octene ring system. Non-covalent interactions present in the crystal structure of
II
include a number of C—H...O interactions. The extended structure of
II
also features C—H...O hydrogen bonds as well as C—H...π and lone pair–π interactions, which combine together to create supramolecular sheets.
Five new neolignans with a bicyclo2.2.2octene framework were isolated from an ethanolic extract of the bark of Cordia americana. The structures and relative configurations of the compounds were ...elucidated by a combination of spectroscopic methods. All the isolated compounds showed good antioxidant activities in the DPPH radical scavenging (0.5-100 µg/mL) and Ferric-reducing antioxidant power (FRAP, 1-100 µg/mL) assays. One of the compounds displayed mild fungistatic activity at 0.1 µmol/spot against Fusarium virguliforme while, at the same time, all compounds were inactive against several strains of Gram (+) and Gram (-) bacteria at all assayed concentrations (10-1,000 µg/mL).
The compounds: 11-trimethylsilyloxy-1,2,3,4,4a,9a-hexahydro-1,4-etheno-anthraquinone and 4-benzyl-8-trimethylsilyloxy-4-aza-tricyclo5.2.2.0undec-8-ene-3,5-dione were synthesized by the Diels–Alder
4
...π
s
+
2
π
s
cycloaddition reaction of 2-(trimethylsilyloxy)-1,3-cyclohexadiene with naphthaquinone and
N
-benzylmaleimide under ultrasonic conditions. The crystal structure analysis was done using single crystal X-ray diffraction method. In both the compounds, the trimethylsilyloxy- and naphthaquinone/
N
-benzylmaleimide moieties are
endo
- to the bicyclic ring.
Graphical Abstract
The synthesis of two novel trimethylsilyloxy- substituted bicyclo2.2.2octene derivatives by employing ultrasonic reaction conditions is reported. The compounds have been characterized by single crystal X-ray studies.
A new analogue of the antitumor pericosines possessing a bicyclo2.2.2octene skeleton has been synthesized from methyl gallate using oxidative dearomatization and regio- and diastereoselective ...Diels–Alder reaction as the key steps.
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Polypyrrole annelated with bicyclo2.2.2octene provides a new material that possesses a raised HOMO band, extended conjugation and a rigid porous structure.
Graphic
The synthesis of
syn-sesterbicyclo2.2.2octene (
7
) bilaterally grafted by an exocyclic
s-
cis-butadiene moiety is achieved from 1,8,9,10-tetrachloro-11,11-dimethoxy-
endo-tricyclo6.2.1.0
...2,7undeca-3,5,9-triene (
8
) employing repetitive Diels–Alder cycloadditions between 1,3-cyclohexadiene, generated from
p-benzoquinone, and diethyl fumarate or maleic anhydride as the exocyclic butadienyl equivalent, followed by subsequent transformation to the conjugated diene moieties. In comparison with the corresponding sesquibicyclo2.2.2octene
6
, the
1H NMR demonstrates the anisotropic shielding effect operating within the three parallel laticyclic double bonds. However, the UV absorption of
7
shows less effect by the increase of laticyclic conjugated ethylene units.
Graphic
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