Crown Ether-Catalyzed Synthesis of Fulvenes in a Solid-Liquid Two-Phase System

Alper, Howard; Laycock, David E.

doi:10.1055/s-1980-29207

Cited by 19 publications

(11 citation statements)

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“…These failures suggested that the reverse approach first used by Thiele, in which the anion 21 derived from cyclopentadiene 7 is reacted with an aldehyde, might be more fruitful. In fact, Ottosson’s procedure, in which the pure anion 21 is isolated and reacted with aldehyde in the absence of base, and Shimizu’s procedure, in which 7 in aqueous THF is reacted with aldehyde in the presence of base and a phase-transfer reagent, both worked. With acetaldehyde, methylfulvene 10 was obtained in 68 and 30% yield, respectively, while with benzaldehyde, phenylfulvene 22 was obtained in 80 and 74% yield, respectively.…”

Section: Resultsmentioning

confidence: 99%

Measuring Aromaticity with the Dimethyldihydropyrene Ring Current Probe. Experimental and Computational Studies of the Fulvenes and the Strongly Antiaromatic Cyclopentadienone Reveal Large Mills−Nixon-Type Bond Localization Effects. Synthesis of Fulvene-Fused Dihydropyrenes

et al. 2008

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The synthesis of the methylfulvene- and phenylfulvene-annelated dihydropyrenes 10 and 22 from the cyclopentadiene-fused dihydropyrene 7 in 68% and 80% yields, respectively, are reported. However, the attempted formation of the parent fulvene-fused dihydropyrene 18 failed, both from the cyclopentadiene 7 with formaldehyde and from the cyclopentadienone 5 in Wittig-type reactions. Chemical shift data for the methylfulvene (35) and phenylfulvene (36)-fused dihydropyrenes 10 and 22 were used to estimate the reduction in the dihydropyrene nucleus aromaticity (DHPN) (relative to benzene fusion) in 10 and 22 (12-16% and 22-25% respectively). Calculations revealed that this reduction in diatropicity, contrary to the situation with benzene fusion, is not due to any aromaticity of the annelating fulvenes but instead is caused by Mills-Nixon-type effects. We conclude that methyl- and phenylfulvene are nonaromatic. An improved synthetic route to the cyclopentadienone 5 was found in an unprecedented cyclization of the trans-cinnamic acid analogue 29 in 80% yield. This enabled an X-ray structure of 5 to be obtained, for comparison to that of the saturated ketone 4. Even though crystals of 5 and 4 show diastereomeric disorder, when the average bond length data of cyclopentadienone 5 is compared with those of cyclopentenone 4 and the parent and benzo dihydropyrenes 6 and 33, it is clearly evident that 5 has the opposite bond-alternation pattern, consistent with a [4n] fused annulene. From the bond length data, cyclopentadienone has approximately 87% of the effect of a benzene ring on bond alternation, which is in reasonable agreement with the previously found NMR value (78%). Structure and nucleus-independent chemical shift calculations support these results.

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Section: Resultsmentioning

confidence: 99%

Measuring Aromaticity with the Dimethyldihydropyrene Ring Current Probe. Experimental and Computational Studies of the Fulvenes and the Strongly Antiaromatic Cyclopentadienone Reveal Large Mills−Nixon-Type Bond Localization Effects. Synthesis of Fulvene-Fused Dihydropyrenes

et al. 2008

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“…6,6-Diphenylfulvene. (Synthesis modified from ref .) Sodium methoxide (41.00 g, 759.0 mmol), ethanol (500 mL), and benzophenone (125.00 g, 686.0 mmol) were added to a 1 L vessel.…”

Section: Methodsmentioning

confidence: 99%

Mechanism of Isotactic Polypropylene Formation with C₁-Symmetric Metallocene Catalysts

Miller

Bercaw

2006

Organometallics

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The mechanism for isotactic polypropylene formation by the C 1 -symmetric catalyst system [Me 2 C(3-tert-butyl-C 5 H 3 )(C 13 H 8 )]ZrCl 2 /MAO (MAO ) methylaluminoxane, C 13 H 8 ) fluorenylidene) has been examined. Evidence supports an alternating mechanism, where both sites of the metallocene wedge are utilized for monomer insertion, rather than the previously proposed site epimerization (inversion at Zr) following each monomer insertion. As the polymerization temperature increases (0 to 60°C) with lower concentrations of propylene, the site epimerization mechanism begins to compete, as evidenced by an increase in isotacticity. The alternating mechanism also accounts for polypropylene microstructures obtained with Me 2 C(3-R-C 5 H 3 )(Oct)ZrCl 2 /MAO, where Oct ) octamethyloctahydrodibenzofluorenylidene and R ) methyl, cyclohexyl, diphenylmethyl, and with Me 2 C(3-tert-butyl-4-Me-C 5 H 2 )(Oct)ZrCl 2 /MAO. For an Oct-containing catalyst system with R ) 2-methyl-2-adamantyl, unprecedentedly high (for a fluorenylbased metallocene catalyst) isotacticity ([mmmm] > 99%) is obtained; the polymer prepared at 0°C has T m ) 167°C and M w ) 370 000.

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“…All organic solvents were freshly distilled from Na–K alloy or CaH 2 immediately prior to use. 1-OTf- o -carborane, fulvenes, and benzohydroximinoyl chloride , were synthesized according to the reported procedures. Other chemicals were purchased from either Aldrich or Acros Chemical Co. and used as received unless otherwise specified.…”

Section: Experimental Sectionmentioning

confidence: 99%

Broad Scope [4 + 2] Cycloaddition of o-Carboryne with Pentafulvenes Using 1-Li-2-OTf-o-C₂B₁₀H₁₀ as Precursor

2017

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o-Carboryne (1,2-dehydro-o-carborane) generated in situ from 1-Li-2-OTf-o-C 2 B 10 H 10 undergoes an efficient [4 + 2] cycloaddition with pentafulvenes at room temperature to give a series of carboranonorbornenes in good to high isolated yields. This reaction is compatible with many functional groups and has a very broad substrate scope from 6-mono-to 6,6′disubstituted pentafulvenes and from alkyl to aryl substituents. Further transformations of the resultant [4 + 2] cycloaddition products have been carried out, affording various multifunctionalized o-carboranes.

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Crown Ether-Catalyzed Synthesis of Fulvenes in a Solid-Liquid Two-Phase System

Cited by 19 publications

References 0 publications

Measuring Aromaticity with the Dimethyldihydropyrene Ring Current Probe. Experimental and Computational Studies of the Fulvenes and the Strongly Antiaromatic Cyclopentadienone Reveal Large Mills−Nixon-Type Bond Localization Effects. Synthesis of Fulvene-Fused Dihydropyrenes

Measuring Aromaticity with the Dimethyldihydropyrene Ring Current Probe. Experimental and Computational Studies of the Fulvenes and the Strongly Antiaromatic Cyclopentadienone Reveal Large Mills−Nixon-Type Bond Localization Effects. Synthesis of Fulvene-Fused Dihydropyrenes

Mechanism of Isotactic Polypropylene Formation with C₁-Symmetric Metallocene Catalysts

Broad Scope [4 + 2] Cycloaddition of o-Carboryne with Pentafulvenes Using 1-Li-2-OTf-o-C₂B₁₀H₁₀ as Precursor

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Crown Ether-Catalyzed Synthesis of Fulvenes in a Solid-Liquid Two-Phase System

Cited by 19 publications

References 0 publications

Measuring Aromaticity with the Dimethyldihydropyrene Ring Current Probe. Experimental and Computational Studies of the Fulvenes and the Strongly Antiaromatic Cyclopentadienone Reveal Large Mills−Nixon-Type Bond Localization Effects. Synthesis of Fulvene-Fused Dihydropyrenes

Measuring Aromaticity with the Dimethyldihydropyrene Ring Current Probe. Experimental and Computational Studies of the Fulvenes and the Strongly Antiaromatic Cyclopentadienone Reveal Large Mills−Nixon-Type Bond Localization Effects. Synthesis of Fulvene-Fused Dihydropyrenes

Mechanism of Isotactic Polypropylene Formation with C1-Symmetric Metallocene Catalysts

Broad Scope [4 + 2] Cycloaddition of o-Carboryne with Pentafulvenes Using 1-Li-2-OTf-o-C2B10H10 as Precursor

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Mechanism of Isotactic Polypropylene Formation with C₁-Symmetric Metallocene Catalysts

Broad Scope [4 + 2] Cycloaddition of o-Carboryne with Pentafulvenes Using 1-Li-2-OTf-o-C₂B₁₀H₁₀ as Precursor