Arylamine C−N Bond Oxidative Addition to (silox)3Ta (silox = tBu3SiO)

Bonanno, J.B.; Henry, Thomas; Neithamer, David R.; Wolczanski, Peter T.; Lobkovsky, Emil

doi:10.1021/ja960092l

Cited by 124 publications

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References 42 publications

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“…[5][6][7][8][9][10][11][12][13] As a synthetic route to (silox) 3 WN (4, silox ) t Bu 3 SiO), the deoxygenation of (silox) 3 WNO (2) by (silox) 3 Ta (1-Ta) was attempted without success, despite ample precedent in cleavages of epoxides, 10 N 2 O, NO, 11 CO 2 , and CO. 12 A comparison study involving sources of M(silox) 3 (1-M; M ) V, Nb, Ta) revealed that features of deoxygenations of 2 and R 3 PO (R ) Me, Ph, t Bu) are the consequences of electronic effects enforced by a limiting steric environment. ) converted 2 to the nitride.…”

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confidence: 99%

Deoxygenations of (silox)₃WNO and R₃PO by (silox)₃M (M = V, Ta) and (silox)₃NbL (silox = ^tBu₃SiO): Consequences of Electronic Effects

et al. 2001

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Oxygen atom transfers involving terminal metal-oxo functionalities are central to many biological transformations, 1 prominent in applications to organic synthesis, 2-4 and of increasing importance in inorganic systems as synthetic tools, 5-7 objectives in biomimicry, 1,8,9 and targets of fundamental studies. [5][6][7][8][9][10][11][12][13] As a synthetic route to (silox) 3 WN (4, silox ) t Bu 3 SiO), the deoxygenation of (silox) 3 WNO (2) by (silox) 3 Ta (1-Ta) was attempted without success, despite ample precedent in cleavages of epoxides, 10 N 2 O, NO, 11 CO 2 , and CO. 12 A comparison study involving sources of M(silox) 3 (1-M; M ) V, Nb, Ta) revealed that features of deoxygenations of 2 and R 3 PO (R ) Me, Ph, t Bu) are the consequences of electronic effects enforced by a limiting steric environment. ) converted 2 to the nitride. (silox) 3 Nb(η 2 -N,C-4-picoline) (1-Nb-(4-pic), S ) 0) 11 and (silox) 3 NbPMe 3 (1-NbPMe 3 , S ) 1) 14 deoxygenated 2 and formed 4 and (silox) 3 NbO (3-Nb) swiftly at first, then more slowly as the released 4-picoline and PMe 3 inhibited the reactions, respectively. With a 4-picoline scavenger (1-Ta) present in the former, swift cyclometalation to (silox) 2 -HNbOSi t Bu 2 CMe 2 CH 2 (5-Nb, 23°C, <5 min) 14 competed with deoxygenation; 5-Nb then slowly deoxygenated 2, presumably via reversible formation of 1-Nb. The thermodynamics of deoxygenation 15 were investigated by high-level quantum calculations, 16 with (HO) 3 M serving as the model of respective tris-silox centers in 1-M and 3-M. In each case the reaction was extremely exoergic (25°C: M ) V, ∆G°r xn ) -66 kcal/mol; M ) Nb, Ta, -100 kcal/mol). With favorable thermodynamics, the uncompetitive (1-Ta) and relatively slow (1-V, 1-Nb) deoxygenations are puzzling.Since (silox) 3 V (1-V, S ) 1) binds various L (L ) THF, py, etc.), while (silox) 3 Ta (1-Ta, S ) 0) does not, 17 the singlet and triplet states of 1-M were examined via quantum calculations. 16 Figure 1 reveals that 1-V is a triplet at the optimized geometries for, and the TfS barrier is 17 kcal/mol, assuming a facile intersystem crossing. 1-Ta is a singlet at the optimized S ) 0 and S ) 1 geometries and its intersystem crossing barrier is 17 kcal/mol. 1-Nb is a singlet, but the conversion barrier to a triplet of nearly the same energy is 2 kcal/mol. If the approach of (silox) 3 WNO (2) to the 1-M center is linear because of intermolecular silox/silox interactions, then a 4e-repulsion will result in the case of 1-Ta, but successful docking to an S ) 1 intermediate (silox) 3 MONW(silox) 3 (1-M-2) will occur for M ) V, Nb. The additional S-T barrier forced on 1-Ta allows unimolecular cyclometalation to compete with the bimolecular deoxygenation of 2. Table 1 lists the results of R 3 PO deoxygenations by (1-V, Ta) and 1-NbL (L ) 4-pic, PMe 3 ), which are predicted by quantum calculations to be exothermic for V (-15 kcal/mol) and Nb or Ta (-45 kcal/mol) with Me 3 PO. Curiously, 1-Ta and 1-NbL both deoxygenated Me 3 PO and Ph 3 PO, but failed with t Bu 3 PO; 1-Ta cyclomet...

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Deoxygenations of (silox)₃WNO and R₃PO by (silox)₃M (M = V, Ta) and (silox)₃NbL (silox = ^tBu₃SiO): Consequences of Electronic Effects

et al. 2001

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“…RuH 2 (CO)(PPh 3 ) 3 (1) [13a], 1-[2-(dimethylamino)phenyl]-2,2-dimethyl-1-propaone (2a) [5], 2,2-dimethyl-1- [2-(methylamino)phenyl]-1-propanone (2b) [5], and 2,2-dimethyl-1- [2-(1-pyrro-lidinyl)phenyl]-1-propanone (2d) [5] were prepared by literature methods. To a 10 mL Schlenk tube were added in a glove box o-acylaniline 2a (41.5 mg, 0.2 mmol), RuH 2 (CO)(PPh 3 ) 3 (1) (36.7 mg, 0.04 mmol), and p-xylene (0.3 mL), and the mixture was heated for 24 h in an oil bath whose temperature adjusted to 140 C. After the reaction, neicosane (0.1 mmol) was added as an internal standard to the resulting mixture, which was then analyzed by GC. Column chromatography of the crude material (100:1 hexane/EtOAc) afforded 3a as colorless oil (28.4 mg, 87%).…”

Section: Solvent and Materialsmentioning

confidence: 99%

“…To a 10 mL Schlenk tube were added in a glove box o-acylaniline 2a (41.5 mg, 0.2 mmol), RuH 2 (CO)(PPh 3 ) 3 (1) (36.7 mg, 0.04 mmol), olefin 4a (0.045 mL, 0.3 mmol), and p-xylene (0.3 mL), and the mixture was heated for 24 h in an oil bath whose temperature adjusted to 140 C. After the reaction, n-eicosane (0.1 mmol) was added as an internal standard to the resulting mixture, which was then analyzed by GC. Column chromatography of the crude material (100:1 hexane/EtOAc) afforded 5a as pale yellow oil (43.1 mg, 82%).…”

Section: 32mentioning

confidence: 99%

“…As an early example, Fujiwara and coworkers found that oxidative arylation of olefins with anilines proceeds via cleavage of carbonenitrogen bonds in the presence of a stoichiometric amount of palladium salts [2]. Direct observation of oxidative addition of aromatic carbonenitrogen bonds via was achieved by Wolczanski and coworkers using tantalum complexes [3], and Boncella and coworkers also observed a cleavage of a carbonenitrogen bond of an (N-silyl)arylamido molybdenum complex [4]. Catalytic conversion of inert sp 2 carbonenitrogen bonds in anilines has rarely been achieved, and the carbonenitrogen bonds in these compounds are usually activated by conversion to more reactive species such as diazonium salts [7], ammonium salts [8], triazenes [9], and hydrazines [10].…”

Section: Introductionmentioning

confidence: 99%

“…In this reaction, coupling of o-acylanilines with organoboronates was catalyzed by RuH 2 (CO)(PPh 3 ) 3 (1) under toluene refluxing conditions to transform carbonenitrogen bonds into carbonecarbon bonds (Scheme 1). Our recent studies indicated that the reaction proceeded via oxidative addition of the carbone nitrogen bonds, followed by transmetalation with arylboronates and reductive elimination [6].…”

Section: Introductionmentioning

confidence: 99%

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Aus einem Pyrrolring herausgeschnitten wird das Stickstoffzentrum bei der Reaktion von [{(tmeda)NbIICl}2(μ‐Cl)3Li(tmeda)] mit dem Lithiumsalz von 2,5‐Dimethylpyrrol, wobei man das Nitrid‐ und Dienyl‐verbrückte Zweikernkomplexanion 1 erhält (tmeda=N,N,N′,N′‐Tetramethylethylendiamin). Ein weiteres Produkt dieser komplexen Reaktion ist der ebenfalls unter C‐N‐Bindungsspaltung entstandene Amido‐Carben‐Hydrid‐Niobkomplex 2.

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Arylamine C−N Bond Oxidative Addition to (silox)₃Ta (silox = ^tBu₃SiO)

Cited by 124 publications

References 42 publications

Deoxygenations of (silox)₃WNO and R₃PO by (silox)₃M (M = V, Ta) and (silox)₃NbL (silox = ^tBu₃SiO): Consequences of Electronic Effects

Deoxygenations of (silox)₃WNO and R₃PO by (silox)₃M (M = V, Ta) and (silox)₃NbL (silox = ^tBu₃SiO): Consequences of Electronic Effects

Ruthenium-catalyzed reductive deamination and tandem alkylation of aniline derivatives

NbII-Cluster-vermittelte Stickstoffabspaltung aus Pyrrol und Fragmentierung von tmeda

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Arylamine C−N Bond Oxidative Addition to (silox)3Ta (silox = tBu3SiO)

Cited by 124 publications

References 42 publications

Deoxygenations of (silox)3WNO and R3PO by (silox)3M (M = V, Ta) and (silox)3NbL (silox = tBu3SiO): Consequences of Electronic Effects

Deoxygenations of (silox)3WNO and R3PO by (silox)3M (M = V, Ta) and (silox)3NbL (silox = tBu3SiO): Consequences of Electronic Effects

Ruthenium-catalyzed reductive deamination and tandem alkylation of aniline derivatives

NbII-Cluster-vermittelte Stickstoffabspaltung aus Pyrrol und Fragmentierung von tmeda

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Arylamine C−N Bond Oxidative Addition to (silox)₃Ta (silox = ^tBu₃SiO)

Deoxygenations of (silox)₃WNO and R₃PO by (silox)₃M (M = V, Ta) and (silox)₃NbL (silox = ^tBu₃SiO): Consequences of Electronic Effects

Deoxygenations of (silox)₃WNO and R₃PO by (silox)₃M (M = V, Ta) and (silox)₃NbL (silox = ^tBu₃SiO): Consequences of Electronic Effects