Nucleophilie‐Parameter von Alkyl‐ und Arylisocyaniden

Tumanov, Vasily V.; Tishkov, Alexander A.; Mayr, Herbert

doi:10.1002/ange.200605205

Cited by 12 publications

(4 citation statements)

References 37 publications

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“…12). [19,20] We find an exponential decay of the benzhydrylium absorbances, when benzhydrylium ions are combined with a large excess of isocyanides. From the slopes of the linear plots of the pseudo-first-order rate constants versus the isocyanide concentrations we obtain the second-order rate constants, and trapping of the initial reaction products with silylated ketene acetals proves that the reaction, which we have monitored photometrically, is the formation of the nitrilium ions (Fig.…”

Section: Special Issuementioning

confidence: 83%

Do general nucleophilicity scales exist?

Mayr

Ofial

2008

J of Physical Organic Chem

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307

218

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Comprehensive nucleophilicity scales including p-, n-and s-nucleophiles have been constructed using benzhydrylium ions and structurally related quinone methides as reference electrophiles. It is shown how the correlation (Eqn (1)) log k 20-C ¼ s(E R N), where s and N are nucleophile-specific parameters and E is an electrophile-specific parameter, has recently been employed to characterize further classes of nucleophiles (phosphines, amines, isonitriles, trifluoromethanesulfonyl-substituted carbanions) and electrophiles (2-benzylideneindan-1,3-diones and benzylidenebarbituric acids). Practical applications of the reactivity parameters E, N and s for developing Friedel-Crafts alkylations in neutral alcoholic or aqueous solution and for characterizing nucleophilic organocatalysts will be discussed. Eventually, a new correlation equation will be presented, which includes Eqn (1), the Ritchie equation (nucleophilic additions to stabilized carbocations), and the Swain-Scott equation (nucleophilic substitutions of methyl halides) as special cases. Figure 4. The benzhydrylium scale: Basis for a quantitative model of polar organic reactivity Figure 5. Fit of second-order rate constants for electrophile nucleophile combinations (20 8C) to Eqn (1)

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Section: Special Issuementioning

confidence: 83%

Do general nucleophilicity scales exist?

Mayr

Ofial

2008

J of Physical Organic Chem

Self Cite

307

218

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“…www.chemeurj.org silicon substitution increases the N factor by 1 (equivalent to a rate enhancement of 10) with respect to parent alkene. [80] Allenylsilanes have not been directly compared to allylsilanes however the corresponding comparison has been made between allyl-and allenylstannanes in which the latter is less reactive by a factor of 6.5. [81] This correlation is expected to be similar in allyl-versus allenylsilanes.…”

Section: Comparison Between Organosilane Speciesmentioning

confidence: 99%

“…The relative reactivity of silanes on the other hand is more difficult to generalize because it is a function of solvent, Lewis acid, and the reactive center amongst others. For relatively nucleophilic olefins (1,2‐disubstituted), vicinal silicon substitution increases the N factor by 1 (equivalent to a rate enhancement of 10) with respect to parent alkene 80. Allenylsilanes have not been directly compared to allylsilanes however the corresponding comparison has been made between allyl‐ and allenylstannanes in which the latter is less reactive by a factor of 6.5 81.…”

Section: Comparison Between Organosilane Speciesmentioning

confidence: 99%

Vinyl‐, Propargyl‐, and Allenylsilicon Reagents in Asymmetric Synthesis: A Relatively Untapped Resource of Environmentally Benign Reagents

Long¹,

Aye

2009

Chemistry A European J

100

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An up-to-date in-depth review of the current virtues and limitations in the realm of carbonyl addition reactions with allenyl-, propargyl-, and vinylsilicon reagents, encompassing numerous practical as well as pedagogical principles is presented. Comparisons of chemo-, regio-, and stereoselectivity and reactivity are drawn. Synthetic applications and challenges associated with each class of organosilane are discussed threading together the prospects of these green carbanion surrogates.

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“…Thus, the use of appropriate nucleophiles, which can open additional reactions channels, was of interest. So, isonitriles13 came into the focus of our interest, which are known to be good donors, revealing a carbene‐like character with additional functions caused by their zwitterionic nature 14. Because of their unique properties, isonitriles have become indispensable building‐blocks for organic synthesis, especially for the synthesis of heterocycles 15…”

Section: Introductionmentioning

confidence: 99%

Reactivity of Bridged Pentelidene Complexes with Isonitriles: A New Way to Pentel‐Containing Heterocycles

Seidl¹,

Schiffer²,

Bodensteiner³

et al. 2013

Chemistry A European J

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The reaction of [Cp*E{W(CO)5 }2 ] (E=P (1 a), As (1 b); Cp*=1,2,3,4,5-pentamethylcyclopentadienyl) with isonitriles RNC (R=tBu, cyclohexyl (Cy), nBu) depends on the steric demand of the substituent at the isonitrile as well as on the stoichiometry of the starting materials. With tBuNC only the Lewis acid/base adducts [Cp*E{W(CO)5 }2 (CNtBu)] (E=P (2 a), As (2 b)) are formed. The use of Cy and n-butylisonitrile leads first to the formation of the Lewis acid/base adduct, but only at low temperatures. At ambient temperatures, a rearrangement occurs and bicyclo[3.2.0]heptane derivatives of the type [{C(Me)C(CH2 )C(Me)C(Me)C(Me)}C(NR)- E{W(CO)5 }2 ] (E=P, As; R=Cy, nBu) (3 a-Cy, 3 b-Cy, 3 a-nBu and 3 b-nBu) are obtained. The use of a further equivalent of isonitrile results in products revealing two new structural motifs, the four-membered ring derivatives [C(Cp*)N(R)C(NR)E{W(CO)5 }2 ] (4: E=P, As; R=Cy, nBu) and the bicyclic complexes [[{C(Me)C- (CH2 )C(Me)C(Me)C(Me)}C(NR)2 - E{W(CO)5 }2 ] (5: E=As; R=Cy). The reaction pathway depends on the substituent at the isonitrile. By treatment of 1 a with two equivalents of CyNC only a 2H-1,3-azaphosphet complex 4 a-Cy (E=P; R=Cy) is formed. Treatment of 1 b with two equivalents of CyNC exclusively leads to the complex 5 b-Cy (E=As; R=Cy). Treatment of 1 a with two equivalents of nBuNC results in a mixture of complexes, the 2H-1,3-azaphosphet 4 a-nBu (E=P; R=nBu) and the bicyclic complex 5 a-nBu (E=P; R=nBu). For the arsenidene complex 1 b a mixture of the 2H-1,3-azarsete complex 4 b-nBu (E=As; R=nBu) and the bicyclic complex 5 b-nBu (E=P, As; R=Cy, nBu) is obtained. Complex 4 b-nBu is the first example of a 2H-1,3-azarsete complex. All products have been characterized by using mass spectrometry, NMR spectroscopy, and X-ray diffraction analysis.

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Nucleophilie‐Parameter von Alkyl‐ und Arylisocyaniden

Cited by 12 publications

References 37 publications

Do general nucleophilicity scales exist?

Do general nucleophilicity scales exist?

Vinyl‐, Propargyl‐, and Allenylsilicon Reagents in Asymmetric Synthesis: A Relatively Untapped Resource of Environmentally Benign Reagents

Reactivity of Bridged Pentelidene Complexes with Isonitriles: A New Way to Pentel‐Containing Heterocycles

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