Browse
Submit Data
Databases
API
Help

Dataset Information

27 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Five-membered ring annelation in [2.2]paracyclophanes by aldol condensation.

ABSTRACT: Under basic conditions 4,5,12,13-tetraacetyl[2.2]paracyclophane (9) cyclizes by a double aldol condensation to provide the two aldols 12 and 15 in a 3:7 ratio. The structures of these compounds were obtained from X-ray structural analysis, spectroscopic data, and mechanistic considerations. On acid treatment 12 is dehydrated to a mixture of the condensed five-membered [2.2]paracyclophane derivatives 18-20, whereas 15 yields a mixture of the isomeric cyclopentadienones 21-23. The structures of these elimination products are also deduced from X-ray and spectroscopic data. The sequence presented here constitutes the simplest route so far to cyclophanes carrying an annelated five-membered ring.

SUBMITTER: Hopf H

PROVIDER: S-EPMC4168897 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Five-membered ring annelation in [2.2]paracyclophanes by aldol condensation.

Hopf Henning H Narayanan Swaminathan Vijay SV Jones Peter G PG

Beilstein journal of organic chemistry 20140828

Under basic conditions 4,5,12,13-tetraacetyl[2.2]paracyclophane (9) cyclizes by a double aldol condensation to provide the two aldols 12 and 15 in a 3:7 ratio. The structures of these compounds were obtained from X-ray structural analysis, spectroscopic data, and mechanistic considerations. On acid treatment 12 is dehydrated to a mixture of the condensed five-membered [2.2]paracyclophane derivatives 18-20, whereas 15 yields a mixture of the isomeric cyclopentadienones 21-23. The structures of th ...[more]

PMID: 25246961

Similar Datasets

Selenium halide-induced bridge formation in [2.2]paracyclophanes.

Project description:An addition/elimination sequence of selenium halides to pseudo-geminally bis(acetylene) substituted [2.2]paracyclophanes leads to new bridges with an endo-exo-diene substructure. The reactions have been found to be sensitive to the substitution of the ethynyl group. The formation of dienes with a zig-zag configuration is related to that observed for non-conjugated cyclic diynes of medium ring size.

| S-EPMC4222412 | biostudies-literature

Building complex carbon skeletons with ethynyl[2.2]paracyclophanes.

Project description:Ethynyl[2.2]paracyclophanes are shown to be useful substrates for the preparation of complex, highly unsaturated carbon frameworks. Thus both the pseudo-geminal- 2 and the pseudo-ortho-diethynylcyclophane 4 can be dimerized by Glaser coupling to the respective dimers 9/10 and 11/12. Whereas the former isomer pair could not be separated so far, the latter provided the pure diastereomers after extensive column chromatography/recrystallization. Isomer 11 is chiral and could be separated on a column impregnated with cellulose tris(3,5-dimethylphenyl)carbamate. The bridge-extended cyclophane precursor 18 furnished the ring-enlarged cyclophanes 19 and 20 on Glaser-Hay coupling. Cross-coupling of 4 and the planar building block 1,2-diethynylbenzene (1) yielded the chiral hetero dimer 22 as the main product. An attempt to prepare the biphenylenophane 27 from the triacetylene 24 by CpCo(CO)2-catalyzed cycloisomerization resulted in the formation of the cyclobutadiene Co-complex 26. Besides by their usual spectroscopic and analytical data, the new cyclophanes 11, 12, 19, 20, 22, and 26 were characterized by X-ray structural analysis.

| S-EPMC4168697 | biostudies-literature

Synthesis of New Planar-Chiral Linked [2.2]Paracyclophanes-N-([2.2]-Paracyclophanylcarbamoyl)-4-([2.2]Paracyclophanylcarboxamide, [2.2]Paracyclophanyl-Substituted Triazolthiones and -Substituted Oxadiazoles.

Project description:The manuscript describes the synthesis of new racemic and chiral linked paracyclophane assigned as N-5-(1,4(1,4)-dibenzenacyclohexaphane-12-yl)carbamoyl)-5'-(1,4(1,4)-dibenzenacyclohexaphane-12-yl)carboxamide. The procedure depends upon the reaction of 5-(1,4(1,4)-dibenzenacyclohexaphane-12-yl)hydrazide with 5-(1,4(1,4)-dibenzenacyclohexaphane-12-yl)isocyanate. To prepare the homochiral linked paracyclophane of a compound, the enantioselectivity of 5-(1,4(1,4)-dibenzenacyclohexaphane-12-yl)carbaldehyde (enantiomeric purity 60% ee), was oxidized to the corresponding acid, which on chlorination, gave the corresponding acid chloride of [2.2]paracyclophane. Following up on the same procedure applied for the preparation of racemic-carbamoyl and purified by HPLC purification, we succeeded to obtain the target Sp-Sp-N-5-(1,4(1,4)-dibenzenacyclohexaphane-12-yl)carbamoyl)-5'-(1,4(1,4)-dibenzenacyclohexaphane-12-yl)carboxamide. Subjecting N-5-(1,4(1,4)-dibenzenacyclohexaphane-12-yl)hydrazide to various isothiocyanates, the corresponding paracyclophanyl-acylthiosemicarbazides were obtained. The latter compounds were then cyclized to a new series of 5-(1,4(1,4)-dibenzenacyclohexaphane-12-yl)-2,4-dihydro-3H-1,2,4-triazol-3-thiones. 5-(1,4(1,4)-Dibenzenacyclohexaphane-12-yl)-1,3,4-oxadiazol-2-amines were also synthesized in good yields via internal cyclization of the same paracyclophanyl-acylthiosemicarbazides. NMR, IR, and mass spectra (HRMS) were used to elucidate the structure of the obtained products. The X-ray structure analysis was also used as an unambiguous tool to elucidate the structure of the products.

| S-EPMC7436044 | biostudies-literature

Five-Membered Ring Peroxide Selectively Initiates Ferroptosis in Cancer Cells.

Project description:A 1,2-dioxolane (FINO2) was identified as a lead compound from a screen of organic peroxides. FINO2 does not induce apoptosis, but instead initiates ferroptosis, an iron-dependent, oxidative cell death pathway. Few compounds are known to induce primarily ferroptosis. In contrast to the perceived instability of peroxides, FINO2 was found to be thermally stable to at least 150 °C. FINO2 was more potent in cancer cells than nonmalignant cells of the same type. One of the enantiomers was found to be more responsible for the observed activity.

| S-EPMC5507670 | biostudies-literature

Constraint of a ruthenium-carbon triple bond to a five-membered ring.

Project description:The incorporation of a metal-carbon triple bond into a ring system is challenging because of the linear nature of triple bonds. To date, the synthesis of these complexes has been limited to those containing third-row transition metal centers, namely, osmium and rhenium. We report the synthesis and full characterization of the first cyclic metal carbyne complex with a second-row transition metal center, ruthenapentalyne. It shows a bond angle of 130.2(3)° around the sp-hybridized carbyne carbon, which represents the recorded smallest angle of second-row transition metal carbyne complexes, as it deviates nearly 50° from the original angle (180°). Density functional theory calculations suggest that the inherent aromatic nature of these metallacycles with bent Ru?C-C moieties enhances their stability. Reactivity studies showed striking observations, such as ambiphilic reactivity, a metal-carbon triple bond shift, and a [2 + 2] cycloaddition reaction with alkyne and cascade cyclization reactions with ambident nucleophiles.

| S-EPMC6014718 | biostudies-literature

A Planar Five-Membered Aromatic Ring Stabilized by Only Two π-Electrons.

Project description:Many chemicals known today are partially or fully aromatic, since a ring framework experiences additional stabilization through the delocalization of π-electrons. While aromatic rings with equal numbers of π-electrons and ring atoms such as benzene are particularly stable, those with the minimally required two π-electrons are very rare and yet remain limited to three- and four-membered rings if not stabilized in the coordination sphere of heavy metals. Here we report the facile synthesis of a dipotassium cyclopentagallene, a unique example of a five-membered aromatic ring stabilized by only two π-electrons. Single-crystal X-ray diffraction revealed a planar Ga5 ring with almost equal gallium-gallium bond lengths, which together with computational and spectroscopic data confirm its aromatic character. Our results prove that aromatic stabilization goes far beyond what has previously been assumed as minimum π-electron count in a five-atom ring fragment.

| S-EPMC9401857 | biostudies-literature

Substituent effect on inter-ring interaction in paracyclophanes.

Project description:The theoretical calculations, namely multipole-derived charge analysis, quantum theory of atom in molecules, and non-bonding interaction (NCI), were performed for [2.2]paracyclophanes, [2.2]paracyclophane-7,9-dienes, and [3.3]paracyclophanes optimized at B3LYP/6-311++G** level, including dispersion correction. The substituent effect of the electron donor N(Me)2 and electron acceptor NO2 group and the influence of the length of bridges joining the aromatic ring on aromatic ring interaction energy (AIE) and strain energy were discussed. The local and electrostatic character of the substituent effect in paracyclophanes was shown. The presence of the weak orbital through-space C···C interaction between the [3.3]paracyclophane ring and weak CH···O hydrogen bonds between the substituents in the different rings was shown.

| S-EPMC7033074 | biostudies-literature

Enantioselective Synthesis of Five-Membered-Ring Atropisomers with a Chiral Rh(III) Complex.

Project description:Axially chiral atropisomeric compounds are widely applied in asymmetric catalysis and medicinal chemistry, and efficient methods for their synthesis are in high demand. This applies in particular to atropisomers derived from five-membered aromatic rings because their lower barrier for rotation among the biaryl axis limits their asymmetric synthesis. We report here an enantioselective C-H functionalization method using our chiral RhJasCp complex for the synthesis of the biaryl atropisomer types that can be accessed from three different five-membered-ring heterocycles.

| S-EPMC7735750 | biostudies-literature

Circular Dichroisms of Mono- and Dibromo[2.2]paracyclophanes: A Combined Experimental and Theoretical Study.

Project description:Circular dichroisms (CDs) of planar chiral 4-bromo[2.2]paracyclophane (1) and three isomeric dibromo[2.2]paracyclophanes (p-2, m'-2, and o'-2) were investigated experimentally and theoretically. They all exhibited strong multisignate Cotton effects (CEs) at the 1Lb, 1La, and 1B transitions of the component (bromo)benzene chromophore and were comparable to each other. For all of the cyclophanes examined, the enantiomer that eluted earlier from a chiral high-performance liquid chromatography column (Chiralcel IA or IB) exhibited negative and positive CEs at the 1Lb and 1La bands, respectively, which were followed by a more complicated pattern of CDs at the higher-energy bands. These CD features were well reproduced by quantum chemical calculations, allowing us to unambiguously assign the absolute configurations of the first-eluted enantiomers as R p in all of the cases examined. Interestingly, the CDs of 1 and 2, although largely comparable in shape, were still sensitive to the number and pattern of bromine substitution, showing closer resemblance between m'-2 and o'-2 and between p-2 and 1. The theoretical calculations also reproduced successfully these spectral resemblance between them. The anisotropy (g) factors for the 1Lb bands of these cyclophanes were considerably large (∼10-2), whereas those for the 1La band were conventional in the order of 10-3. In addition, a weak CE was observed in the low-energy region at around 320 nm, which turned out to originate from the interplanar interaction and is hence assigned to the "cyclophane band". The experimental g factors of this band were fairly large in the order of 10-2, but the computation turned out to be quite challenging and were less well reproduced theoretically, ascribable to the forbidden nature of the transition.

| S-EPMC6641403 | biostudies-literature

Nucleophilic addition to silyl-protected five-membered ring oxocarbenium ions governed by stereoelectronic effects.

Project description:A series of fused-bicyclic acetals containing a disiloxane ring was investigated to evaluate the source of selectivity in silyl-protected 2-deoxyribose systems. The disiloxane ring unexpectedly enables the diaxial conformer of the cation to be stabilized by an electronegative atom at C-3. This low energy conformer subsequently undergoes stereoelectronically controlled nucleophilic addition to give substituted tetrahydrofurans with high diastereoselectivity.

| S-EPMC3713616 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data