[2 + 4] Cycloadditions between germenes and .alpha.-ethylenic aldehydes and ketones: a route to germaoxacyclohexenes

Lazraq, M.; Escudié, J.; Couret, C.; Satgé, J.; Soufiaoui, M.

doi:10.1021/om00038a009

Cited by 25 publications

(12 citation statements)

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“…The reactivity of metallenes and dimetallenes with ethylenic ketones has been shown to follow a certain order, loosely based upon the polarity of the reacting double bond. For example, nonpolar disilenes 11 exclusively undergo [2 + 2] additions with the carbonyl double bond, whereas the more polar germenes undergo [2 + 4] cycloadditions, regioselectively, as the sole mode of reaction . The reactivity of tetramesitylgermasilene toward MVK falls between the observed reactivity of disilenes and digermenes, which would be consistent with the slight polarity of the silicon−germanium double bond.…”

Section: Resultsmentioning

confidence: 71%

The Reaction of Group 14 Dimetallenes with Alkenes: Electron-Poor Alkenes

1997

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The addition reactions of tetramesitylgermasilene with methyl vinyl ketone (MVK), crotonaldehyde, and acrylonitrile were studied. When tetramesitylgermasilene was allowed to react with MVK, [2 + 4] cycloaddition and nonregioselective carbonyl [2 + 2] cycloaddition products were isolated. When tetramesitylgermasilene was allowed to react with crotonaldehyde, the carbonyl [2 + 2] adduct was produced exclusively. The regiochemistry was not determined. The addition of acrylonitrile to tetramesitylgermasilene yielded a germasilacyclobutane, which is the formal [2 + 2] cycloadduct between the germasilene and the C-C double bond of acrylonitrile. Tetramesityldisilene was also found to yield a formal [2 + 2] adduct with acrylonitrile. However, tetramesityldigermene rearranges to a germylgermylene at a faster rate than acrylonitrile addition.

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Section: Resultsmentioning

confidence: 71%

The Reaction of Group 14 Dimetallenes with Alkenes: Electron-Poor Alkenes

1997

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“…Interestingly, in no other study of the reactivity of germene 4 toward carbonyl compounds ,,,,, did the germene act as the 4π component in a cycloaddition reaction with the carbonyl group. With our results, a direct comparison can be made between the addition of germene 4 to two different aldehydes: benzaldehyde and trans -(2-phenylcyclopropyl)carboxaldehyde ( 2 ).…”

Section: Resultsmentioning

confidence: 99%

“…The residue was triturated with C 6 D 6 and then centrifuged. The supernatant was analyzed by 1 H NMR spectroscopy and was found to contain germene 4 (88%), [Mes 2 Ge(fluorenyl)] 2 Oa (9%), residual fluorogermane 6 (3%), and traces of Mes 2 GeH(fluorenyl) (<1%). No evidence for the Et 2 O adduct of the germene was observed…”

Section: Methodsmentioning

confidence: 99%

“…Both germenes are stable in solution and can be readily synthesized. The addition of a number of aldehydes and ketones, including diketones and quinones, to germenes 3 and 4 ,,,,, has been reported. Given that the addition of carbonyl compounds to germene 3 often results in the formation of ene adducts, germene 4 was chosen as the substrate for this study.…”

Section: Introductionmentioning

confidence: 99%

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Addition of Aldehydes to Germenes: The Influence of Solvent

Allan¹,

Reinhold²,

Pavelka³

et al. 2011

Organometallics

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The addition of trans-(2-phenylcyclopropyl)carboxaldehyde to dimesitylfluorenylidenegermane produced four diastereomers of a 1,2-oxagermin, 7aÀd, 2,2,4,4tetramesityl-1,3-dioxadigermetane ( 8), and fluorenylidene-(trans-2-phenylcyclopropyl)methane ( 9). The ratio of the products showed a strong dependence on the solvent: 7aÀd were formed almost exclusively when ether or benzene was used as the solvent for the reaction, whereas 1,3-dioxadigermetane 8 and alkene 9 were the major products formed in THF. A mechanism is proposed to account for the observations.

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“…For example, the high synthetic potential of germenes is illustrated by their reaction with carbonyl compounds. Various types of reaction have been observed depending on the structure of the carbonyl derivatives: generally [2 + 2] cycloadditions with saturated aldehydes and ketones, 3 and [2 + 4] cycloadditions with a-ethylenic aldehydes and -ketones 4 or -esters 5 but also enereactions, the germenes behaving either as ene 6 or enophile. 6 In the special case of benzophenone, besides a [2 + 2] cycloaddition, a [2 + 4] cycloaddition involving the phenyl group has also been observed.…”

Section: Introductionmentioning

confidence: 99%