Synthesis of 1-ethyl-2-methyl-3-arylindanes. Stereochemistry of five-membered ring formation

Alesso, Elba N.; Torviso, Rosario; Lantaño, Beatríz; Erlich, Magali; Finkielsztein, Liliana M.; Moltrasio, Graciela Y.; Aguirre, José M.; Brunet, Ernesto

doi:10.3998/ark.5550190.0004.a27

Cited by 23 publications

(5 citation statements)

References 11 publications

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“…Thus, regio- and diastereoselective trapping of the allylic cation 22 by in situ generated indene 9z to give an intermediate tertiary carbocation 23 , followed by intramolecular cyclization to the cation 24 , and selective elimination would provide the 21 . The formation of 21 is an example of a formal [2π + 2π] cycloaddition . The remarkable selectivity exhibited in the formation of 21 can be rationalized, in part, by attack of indene 9z from the less hindered face onto the more electron-deficient position of the allylic cation 22 .…”

Section: Resultsmentioning

confidence: 99%

Investigation of Substituent Effects on the Selectivity of 4π-Electrocyclization of 1,3-Diarylallylic Cations for the Formation of Highly Substituted Indenes

et al. 2010

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Differentially substituted 1,3-diaryl-substituted allylic cations generated by ionization of the corresponding allylic alcohols in the presence of a Lewis acid undergo chemoselective and regioselective electrocyclization reactions to generate 1-aryl-1H-indenes. Electrocyclization only occurs for allylic cations bearing a 2-substituent, with 2-ester and 2-alkyl substituents both tolerated. In general, the presence of electron-withdrawing substituents deactivates the ring and disfavors cyclization. In contrast, the selectivity of cyclization of systems containing electron-donating substituents depends on the nature and position of the electron-donating group. Electron-donating substituents at the meta position particularly favor cyclization. There was no obvious correlation of cyclization selectivity with calculated electron densities as has been suggested for electrophilic aromatic substitution reactions. However, the calculated selectivities determined by a gas-phase (B3LYP/6-31G* + ZPVE) comparison of the relative rates of cyclization were in remarkably good agreement with the observed selectivities. Calculated transition-state structures for cyclization are consistent with a cationic pi4(a) conrotatory electrocyclization mechanism. In some cases involving more electron-deficient systems, the initially formed 1H-indene underwent subsequent alkene isomerization to the 3H-indene. In one example, an unusual dimerization reaction occurred to give a cyclopenta[a]indene via an unusual formal cationic 2pi+2pi cycloaddition of the allylic cation with the intermediate indene.

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Section: Resultsmentioning

confidence: 99%

Investigation of Substituent Effects on the Selectivity of 4π-Electrocyclization of 1,3-Diarylallylic Cations for the Formation of Highly Substituted Indenes

et al. 2010

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“…On the other hand, the benzyl alcohols 1-(3,4-dimethoxyphenyl)propanol ( 11) and 1-(3,4-methylendioxyphenyl)propanol (12) react with styrenes 4-methoxystyrene (13) and 2,4,5-trimethoxystyrene (15) to render two pairs of stereoisomeric indanes 14a, 14b and 16a, 16b, respectively, with identical stereoselectivity to that obtained with SnCl 4 [22] but in a shorter time and with higher yield.…”

Section: Formal [3 + 2] Cycloaddition Reactionsmentioning

confidence: 99%

“…In previous papers, numerous examples of this type of reaction using SnCl 4 as catalyst were published [21,22]. Here, the results obtained using MPA/S as catalyst and the better reaction conditions for each pair of reactants are presented (Table 3).…”

Section: Formal [3 + 2] Cycloaddition Reactionsmentioning

confidence: 99%

C-alkylation reactions catalyzed by silica-supported Keggin heteropolyacids

Pizzio

Vázquez

Cáceres

et al. 2005

Applied Catalysis A: General

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“…Secaloside A (Figure ), found in pollen extract, was responsible for antitumor activity . Synthetic approaches to prepare the arylindanes from benzyl alcohols and benzhydrols with styrene derivatives have also been investigated under acidic conditions. ,, In these reactions, although the phenyl ring substituents were shown to significantly affect the yield and diastereoselectivity, a convincing explanation has not been provided as yet.…”

Section: Introductionmentioning

confidence: 99%

“…2:1) were characterized. 20 Although this type of reaction is known to proceed as a formal [3 + 2] cycloaddition reaction, 14 it is suggested that the methoxy and hydroxy groups attached to the phenyl ring play an important role in the reactivity and stereoselectivity.…”

Section: ■ Introductionmentioning

confidence: 99%

Substituent Effect on the Formation of Arylindanes by Dimerization of Ferulic Acid and its Related Compounds

et al. 2018

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Homodimerization and crossed-dimerization reactions for ferulic acid and related compounds in an acidic ethanol solution were investigated via a formal [3 + 2] cycloaddition reaction. Arylindanes, as the major products, were produced from some of the acids with hydroxy group and/or methoxy groups at the para and meta positions of the phenyl ring. The formation of arylindane required the following consecutive reactions: (I) protonation of the first produced ester to afford to a benzylic cation, (II) which reacts with another ester to afford a new benzylic cation, and (III) followed by cyclization to produce the dimer. It is suggested that the para-substituent promoted both step I and step II and the meta-substituent accelerated step III. To rationalize the selectivity of homodimerization, the stability of the benzyl cations and the specific electron distribution on the molecular surface of each ester is discussed based on the results of the molecular orbital calculations.

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Synthesis of 1-ethyl-2-methyl-3-arylindanes. Stereochemistry of five-membered ring formation

Abstract: A natural dimer of asarone and several analogues were obtained by acid-catalysed cyclodimerisation of styrenes and by formal [3+2] cycloaddition. A study of the influence of the aromatic ring substitution pattern on the stereochemistry of the reactions was carried out.

Cited by 23 publications

References 11 publications

Investigation of Substituent Effects on the Selectivity of 4π-Electrocyclization of 1,3-Diarylallylic Cations for the Formation of Highly Substituted Indenes

Investigation of Substituent Effects on the Selectivity of 4π-Electrocyclization of 1,3-Diarylallylic Cations for the Formation of Highly Substituted Indenes

C-alkylation reactions catalyzed by silica-supported Keggin heteropolyacids

Substituent Effect on the Formation of Arylindanes by Dimerization of Ferulic Acid and its Related Compounds

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