Recent Advances in Group 14 Cross-Coupling: Si and Ge-Based Alternatives to the Stille Reaction

Spivey, Alan C.; Gripton, Christopher J. G.; Hannah, Joseph P.

doi:10.2174/1570179043366765

Cited by 77 publications

(45 citation statements)

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“…17 From the literature precedent summarized above, it was clear that the Ge centre needs to be rendered hypervalent in order to activate the aryl-Ge bond towards transmetallation with Pd. This has been achieved either via intramolecular coordination of a suitably tethered tertiary amine (as in Kosugi's carbagermatranes), or via intermolecular coordination of a halide/hydroxide nucleophile to a susceptible tri-halo-, hydroxyl-or alkoxy arylgermane precursor (as in the methods of Oshima, Faller and Wnuck, and for Kosugi's trichlorogermanes).…”

Section: Resultsmentioning

confidence: 99%

The development of a ‘safety‐catch’ arylgermane for biaryl synthesis by palladium‐catalysed germyl‐stille cross‐coupling

Spivey

Gripton

Hannah

et al. 2007

Applied Organom Chemis

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The Pd(0) catalysed cross-coupling of arylgermanes with aryl bromides is shown to require at least two labile heteroatom ligands on the Ge centre to allow efficient nucleophilic activation by fluoride. Dichloroarylgermanes 7a and 7b are shown to cross-couple to a series of aryl bromides with moderate efficiency using activation by KF in DMF. Bis(2-naphthylmethyl)arylgermane 18b is identified as a 'safety-catch' precursor to this type of cross-coupling substrate. The 2-naphthylmethyl substituents can be removed via photolytic oxidation in the presence of Cu(BF 4 ) 2 and the resulting species, although not characterized, participates in cross-coupling using activation by TBAF in DMF.

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Section: Resultsmentioning

confidence: 99%

The development of a ‘safety‐catch’ arylgermane for biaryl synthesis by palladium‐catalysed germyl‐stille cross‐coupling

Spivey

Gripton

Hannah

et al. 2007

Applied Organom Chemis

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“…In this context, the use of organosilicon reagents in palladium-catalysed cross-coupling has attracted the attention of synthetic chemists. [12][13][14][15][16] Organosilicon reagents have a number of unique advantages over other organometallic species including low toxicity, high stability, low molecular weight and ease of introduction into various substrates. [12,13,15] Seminal studies by Hiyama and Hatanaka established that a range of alkenyl-, alkynyl and allyltrimethylsilanes could undergo palladium-catalysed cross-coupling with aryl, vinyl and allyl halides through activation of the silicon-carbon bond with fluoride ions to facilitate transmetallation.…”

Section: Introductionmentioning

confidence: 99%

Aryl–Aryl Bond Formation by the Fluoride‐Free Cross‐Coupling of Aryldisiloxanes with Aryl Bromides

Boehner

Frye

O’Connell

et al. 2011

Chemistry A European J

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The prevalence of the biaryl structural motif in biologically interesting and synthetically important molecules has inspired considerable interest in the development of methods for aryl-aryl bond formation. Herein we describe a novel strategy for this process involving the fluoride-free, palladium-catalysed cross-coupling of readily accessible aryldisiloxanes and aryl bromides. Using a statistical-based optimisation process, preparatively useful reaction conditions were formulated to allow the cross-coupling of a wide range of different substrates. This methodology represents an attractive, cost-efficient, flexible and robust alternative to the traditional transition-metal-catalysed routes typically used to generate molecules containing the privileged biaryl scaffold.

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“…Reactivity of these hypervalent Ge species could be superior in toluene solvent due to the weak solvation. Water might play multiple roles in enhancing the efficiency of the couplings as was found with organosilanes, including the formation of the reactive hydroxypalladium intermediates 1,23,24. For example, the hydration level of Cs 2 CO 3 and CsOH were found to be a decisive factor during the coupling of the aryl(dimethyl)silanols with aryl halides 25.…”

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confidence: 96%

“…The Pd-catalyzed cross-coupling of organogermanes has thus far received much less attention1 than the couplings involving organostannanes and organosilanes 2. This is due to the lower reactivity of tetracoordinated organogermanium species, the less developed syntheses of vinyl/aryl germanyl derivatives, and the higher cost of germanium relative to silicon 3.…”

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confidence: 99%

Arylchlorogermanes/TBAF/“Moist” Toluene: A Promising Combination for Pd-Catalyzed Germyl-Stille Cross-Coupling

et al. 2010

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The trichlorophenyl,-dichlorodiphenyl,-and chlorotriphenylgermanes undergo Pd-catalyzed crosscouplings with aryl bromides and iodides in the presence of TBAF in toluene with addition of the measured amount of water. One chloride ligand on the Ge center allows efficient activation by fluoride to promote transfer of one, two or three phenyl groups from the organogermane precursors.The Pd-catalyzed cross-coupling of organogermanes has thus far received much less attention 1 than the couplings involving organostannanes and organosilanes. 2 This is due to the lower reactivity of tetracoordinated organogermanium species, the less developed syntheses of vinyl/aryl germanyl derivatives, and the higher cost of germanium relative to silicon. 3 The carbagermatranes 1, with internal coordination of nitrogen to germanium, were the first examples of reactive tetracoordinated germanes applied to Pd-catalyzed cross-coupling reactions with aryl bromides 4 (Figure 1). The oxagermatranes 2 were found to be more efficient than carbagermatranes and triethoxygermanes. 5,6 Fluoride-promoted couplings with aryltri(2-furyl)germanes 7 and NaOH-activated couplings with arylgermanium trichlorides 8 or their hydrolyzed and stable sesquioxide alternatives 9 were also reported. The bis(2-naphthylmethyl) arylgermanes 3 were developed as photochemically activated arylgermanes for the synthesis of biaryls. 10,11 The vinyl tris(trimethylsilyl)germanes 4 were employed as transmetalation reagents in "ligand-and fluoride-free" coupling reactions with halides under oxidative wnuk@fiu.edu. † On faculty leave from

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Recent Advances in Group 14 Cross-Coupling: Si and Ge-Based Alternatives to the Stille Reaction

Cited by 77 publications

References 0 publications

The development of a ‘safety‐catch’ arylgermane for biaryl synthesis by palladium‐catalysed germyl‐stille cross‐coupling

The development of a ‘safety‐catch’ arylgermane for biaryl synthesis by palladium‐catalysed germyl‐stille cross‐coupling

Aryl–Aryl Bond Formation by the Fluoride‐Free Cross‐Coupling of Aryldisiloxanes with Aryl Bromides

Arylchlorogermanes/TBAF/“Moist” Toluene: A Promising Combination for Pd-Catalyzed Germyl-Stille Cross-Coupling

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