Multiple Dissolving-Metal Reduction of Centropolyindans: Synthesis of a Hexakis(cyclohexano)centrohexaquinacene

Eckrich, Ralf; Kuck, Dietmar

doi:10.1055/s-1993-22449

Cited by 22 publications

(25 citation statements)

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“…For the synthesis of octahydro-1H-indene (5), the Benkeser reduction reaction, [26][27][28] was used, which is a hydrogenation of aromatic hydrocarbons, using lithium or calcium metal and any of the primary amines as reductants. A modified tetraline reduction procedure 26 was applied to indane (7).…”

Section: Resultsmentioning

confidence: 99%

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High temperature bromination Part XXIII: Bromination of octahydro-1H-indene and octahydro-1H-4,7-methanoindene

Özer¹,

Kılbaş²,

Balcı³

2013

Arkivoc

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Thermal and photobromination of octahydro-1H-indene and octahydro-1H-4,7-methanoindene were investigated. Three isomeric tetrabromides (1,3,4,7-tetrabromo-2,3,4,5,6,7-hexahydro-1H-indene) were formed along with a smaller amount of tribromoindane and a pentabromide by thermal bromination of octahydro-1H-indene. The thermodynamically most stable isomers were formed. Morover, thermal and photochemical bromination of octahydro-1H-4,7-methanoindene furnished bromides resulting regiospecifically from the allylic bromination of the five-membered ring. Furthermore, the double bond formed as the intermediate functional group was also brominated due to its pyramidalization. The mechanism proposed for the formation of product distribution was discussed.

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Section: Resultsmentioning

confidence: 99%

“…A modified tetraline reduction procedure 26 was applied to indane (7). Treatment of indane (7) with lithium in ethylenediamine gave a mixture of 2,3,4,7-tetrahydro-1H-indene (8) and 2,3,3a,4,5,6-hexahydro-1H-indene (9) in a ratio of 76:24 (60.0% yield) (Scheme 2).…”

Section: Resultsmentioning

confidence: 99%

High temperature bromination Part XXIII: Bromination of octahydro-1H-indene and octahydro-1H-4,7-methanoindene

Özer¹,

Kılbaş²,

Balcı³

2013

Arkivoc

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“…[13] The stereochemistry of 7 b and 7 c followed from the characteristic 1 H NMR chemical shifts and coupling constants of the cis-alkene units. [11,13,17] A cursory appraisal of the results would suggest a common mechanism of the first step of these transformations, namely all-disrotatory cyclohexane retro-[2+2+2]cycloaddition to the corresponding all-cis [12]annulenes 7, among which 7 a could be rendered unobservable by relatively fast further transformation to 8 a. However, calculations of this pathway revealed a trend, if small, opposite to that observed.…”

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confidence: 91%

“…[6] More generally, such cyclohexane cycloreversions constitute one strategy for gaining access to the interior of fullerenes. [7] In addition, triene 1 (and its derivatives) are of importance structurally, because of their potential central-ring planarity, [8] and synthetically, as new precursors to novel [12]annulene isomers [9] and as new 6p-electron ligands for catalysis.[10]We report the synthesis, structure, and thermal rearrangement of the first example of structural motif 1, namely the triply annelated hydrocarbon 2 and its congeners 3 and 4, and compare their behavior to that of their common precursor, the trisbenzo analogue 5, [11] for which all-disrotatory retro-[2+2+2]cycloaddition has been proposed. [11b] To assist in the interpretation of the results, DFT calculations were employed.…”

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confidence: 99%

“…[11b] To assist in the interpretation of the results, DFT calculations were employed. These calculations suggested an unexpected switch-over in the mechanism of cyclohexane ring fissure along the series.Birch reduction [12] of 5 [11b] could be controlled to give 6 a, either pure (93 %), or admixed with varying amounts (depending on the quantity of lithium used) of the mono-(6 b) and bisbenzo relatives (6 c), which were separated by column chromatography.[13] Selective dihydrogenation with Wilkinsons catalyst then furnished the targets 2-4, respectively, in good yields. Inspection of the NMR spectroscopic data of the series 2-5 reveals the trends expected for progressive, peripheral aromatization.…”

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The Thermal Retro[2+2+2]cycloaddition of Cyclohexane Activated by Triscyclobutenannelation: Concerted All‐Disrotatory versus Stepwise Conrotatory Pathways to Fused [12]Annulenes

et al. 2007

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The unknown C 3v -symmetric all-cis triscyclobutenocyclohexane 1[1] is of fundamental interest as a key structure on which to probe the mechanism of [2+2+2]cycloreversions of cyclopropa-and cyclobuta-fused cyclohexanes ("tris-s-homobenzenes").[ [3] which is the result of unfavorable through-bond interactions. [2c,d] In contrast, the double bonds in 1 should not only activate by introducing further strain, [4] but also enable additional orbital symmetry control in the form of stepwise conrotatory cyclobutene ring openings, conflicting stereochemically with a concerted all-disrotatory unraveling of the cyclohexane ring. While conrotatory motion is seemingly constrained in bicyclo[n.2.0]alkenes, leading to much speculation regarding the feasibility of forbidden disroratory pathways in such systems, [5] cis-bicyclo[4.2.0]oct-7-ene, the pertinent subunit of 1 (highlighted), chooses this option. [6] More generally, such cyclohexane cycloreversions constitute one strategy for gaining access to the interior of fullerenes. [7] In addition, triene 1 (and its derivatives) are of importance structurally, because of their potential central-ring planarity, [8] and synthetically, as new precursors to novel [12]annulene isomers [9] and as new 6p-electron ligands for catalysis.[10]We report the synthesis, structure, and thermal rearrangement of the first example of structural motif 1, namely the triply annelated hydrocarbon 2 and its congeners 3 and 4, and compare their behavior to that of their common precursor, the trisbenzo analogue 5, [11] for which all-disrotatory retro-[2+2+2]cycloaddition has been proposed. [11b] To assist in the interpretation of the results, DFT calculations were employed. These calculations suggested an unexpected switch-over in the mechanism of cyclohexane ring fissure along the series.Birch reduction [12] of 5 [11b] could be controlled to give 6 a, either pure (93 %), or admixed with varying amounts (depending on the quantity of lithium used) of the mono-(6 b) and bisbenzo relatives (6 c), which were separated by column chromatography.[13] Selective dihydrogenation with Wilkinsons catalyst then furnished the targets 2-4, respectively, in good yields. Inspection of the NMR spectroscopic data of the series 2-5 reveals the trends expected for progressive, peripheral aromatization. Noticeable are the fairly invariant chemical shifts of the central cyclohexane carbon atoms, namely d = 43.3, 42.3 (average), 41.5 (average), and 40.6 ppm, respectively, and the small shielding trend, reflecting that observed for the corresponding carbon atoms in cyclobutene (d = 31.4 ppm) and benzocyclobutene (d = 29.5 ppm). Because of their novelty, X-ray structural analyses

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Benkeser Reduction

2010

Comprehensive Organic Name Reactions and Reagents

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Benkeser reduction is the reduction of aromatic and olefinic compounds with lithium or calcium to unsaturated olefins and fully reduced hydrocarbons in the presence of low molecular weight amines. It has been found that low molecular weight monoamines, particularly methylamine and ethylamine, are excellent media for reduction with lithium. The study finds that the neat monoamines, aromatic compounds are reduced to mono olefins, whereas in monoamine‐alcohol solution, di‐olefins are obtained. The Benkeser reduction in ethylenediamine frequently results in overreduction of the substrate, giving a mixture of products. This drawback has been overcome by using 1 mole of ethylenediamine or N, N ′‐dimethylethylenediamine per gram‐atom of lithium with or without the proton donor (alcohol). So far, the lithium‐reducing systems have been applied to this type of reaction. The amination to hydrocarbon has also been reported under certain conditions. The calcium‐reducing systems have also been applied extensively besides electrochemical‐reducing systems.

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Multiple Dissolving-Metal Reduction of Centropolyindans: Synthesis of a Hexakis(cyclohexano)centrohexaquinacene

Cited by 22 publications

References 0 publications

High temperature bromination Part XXIII: Bromination of octahydro-1H-indene and octahydro-1H-4,7-methanoindene

High temperature bromination Part XXIII: Bromination of octahydro-1H-indene and octahydro-1H-4,7-methanoindene

The Thermal Retro[2+2+2]cycloaddition of Cyclohexane Activated by Triscyclobutenannelation: Concerted All‐Disrotatory versus Stepwise Conrotatory Pathways to Fused [12]Annulenes

Benkeser Reduction

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