The Electrophilic Nature of Carbenoids, Nitrenoids, and Oxenoids

Boche, Gernot; Lohrenz, John C. W.

doi:10.1021/cr940260x

Cited by 318 publications

(210 citation statements)

References 345 publications

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“…[29] Metal oxenoid and metal carbenoid species are isoelectronic, and optically active metallosalen and related complexes have been used as catalysts not only for asymmetric epoxidations but also for asymmetric cyclopropanations, though the most suitable metal center varies with the asymmetric reaction examined. [30] For example, optically active [MnA C H T U N G T R E N N U N G (salen)] complexes catalyze asymmetric epoxidation as described above, whereas optically active [CoA C H T U N G T R E N N U N G (salen)] and [Co(aldiminate)] complexes catalyze asymmetric cyclopropanation.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Metal–(Pentadentate‐Salen) Complexes: Asymmetric Epoxidation with Aqueous Hydrogen Peroxide and Asymmetric Cyclopropanation (salenH₂: N,N′‐bis(salicylidene)ethylene‐1,2‐diamine)

Shitama

Katsuki

2007

Chemistry A European J

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It is known that the rates and stereochemical outcomes of epoxidations and cyclopropanations using a metallosalen (salenH(2): N,N'-bis(salicylidene)ethylene-1,2-diamine) complex as catalyst are affected by a trans effect of the apical ligand of the complex. By taking into consideration this trans effect, we have synthesized optically active pentadentate salen ligands bearing an imidazole or pyridine derivative as the fifth coordinating group, and have prepared the corresponding manganese(III) and cobalt(II) complexes, in which the fifth ligand is expected to intramolecularly coordinate to the metal center and exert a trans effect. Indeed, high enantioselectivity has been achieved in epoxidations using aqueous hydrogen peroxide as the terminal oxidant and in cyclopropanations with these complexes as catalysts. In general, metallosalen-catalyzed reactions have been carried out in the presence of an excess of a donor ligand; however, the present reactions do not need the addition of any extra donor ligand.

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Section: Introductionmentioning

confidence: 99%

Synthesis of Metal–(Pentadentate‐Salen) Complexes: Asymmetric Epoxidation with Aqueous Hydrogen Peroxide and Asymmetric Cyclopropanation (salenH₂: N,N′‐bis(salicylidene)ethylene‐1,2‐diamine)

Shitama

Katsuki

2007

Chemistry A European J

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“…At this point, H/D exchange can occur when D 2 is present, since hydrogen addition to a singlet carbene is generally rapid. The carbene radical anion 20,21 can also attack C(9) in another molecule, eliminating a hydride, forming 3. This step accounts for the HD formation in the cross-over experiment.…”

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confidence: 99%

Thermal Dihydrogen Elimination from Cp*₂Yb(4,5-diazafluorene)

et al. 2012

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The reaction of 4,5-diazafluorene with Cp* 2 Yb(OEt 2 ), where Cp* is pentamethylcyclopentadienyl, affords the isolable adduct Cp* 2 Yb(4,5-diazafluorene) (1), which slowly eliminates H 2 to form Cp* 2 Yb(4,5-diazafluorenyl) (2); the net reaction is therefore 1 → 2 + H • . The ytterbium atom in 1 is shown to be intermediate valent by variable-temperature L III -edge X-ray absorption near-edge (XANES) spectroscopy, consistent with its low effective magnetic moment (μ eff ). The experimental studies are supported by complete active space self-consistent field (CASSCF) calculations, showing that two open-shell singlets lie below the triplet state. The two open-shell singlets are calculated to be multiconfigurational and closely spaced, in agreement with the observed temperature dependence of the XANES and χ data, which are fit to a Boltzmann distribution. A mechanism for dihydrogen formation is proposed on the basis of kinetic and labeling studies to involve the bimetallic complex (Cp* 2 Yb) 2 (4,5diazafluorenyl) 2 , in which the heterocyclic amine ligands are joined by a carbon−carbon bond at C(9)−C(9′).

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“…[134][135][136][137][138][139][140][141][142][143] Genêt and co-workers aminated aryl, primary and secondary alkyllithiums using lithium tbutyl-N-tosyloxycarbamate (LiBTOC), 21a, to synthesize primary amines in their N-Boc protected form (Scheme 45). 116,117,119 LiBTOC 21a reacts with organolithium reagents according to the mechanism proposed by Beak and coworkers.…”

Section: Scheme 44mentioning

confidence: 99%

Synthesis of amines by the electrophilic amination of organomagnesium, -zinc, -copper, and -lithium reagents

Daşkapan

2011

Arkivoc

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The Electrophilic Nature of Carbenoids, Nitrenoids, and Oxenoids

Cited by 318 publications

References 345 publications

Synthesis of Metal–(Pentadentate‐Salen) Complexes: Asymmetric Epoxidation with Aqueous Hydrogen Peroxide and Asymmetric Cyclopropanation (salenH₂: N,N′‐bis(salicylidene)ethylene‐1,2‐diamine)

Synthesis of Metal–(Pentadentate‐Salen) Complexes: Asymmetric Epoxidation with Aqueous Hydrogen Peroxide and Asymmetric Cyclopropanation (salenH₂: N,N′‐bis(salicylidene)ethylene‐1,2‐diamine)

Thermal Dihydrogen Elimination from Cp*₂Yb(4,5-diazafluorene)

Synthesis of amines by the electrophilic amination of organomagnesium, -zinc, -copper, and -lithium reagents

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The Electrophilic Nature of Carbenoids, Nitrenoids, and Oxenoids

Cited by 318 publications

References 345 publications

Synthesis of Metal–(Pentadentate‐Salen) Complexes: Asymmetric Epoxidation with Aqueous Hydrogen Peroxide and Asymmetric Cyclopropanation (salenH2: N,N′‐bis(salicylidene)ethylene‐1,2‐diamine)

Synthesis of Metal–(Pentadentate‐Salen) Complexes: Asymmetric Epoxidation with Aqueous Hydrogen Peroxide and Asymmetric Cyclopropanation (salenH2: N,N′‐bis(salicylidene)ethylene‐1,2‐diamine)

Thermal Dihydrogen Elimination from Cp*2Yb(4,5-diazafluorene)

Synthesis of amines by the electrophilic amination of organomagnesium, -zinc, -copper, and -lithium reagents

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Product

Resources

About

Synthesis of Metal–(Pentadentate‐Salen) Complexes: Asymmetric Epoxidation with Aqueous Hydrogen Peroxide and Asymmetric Cyclopropanation (salenH₂: N,N′‐bis(salicylidene)ethylene‐1,2‐diamine)

Synthesis of Metal–(Pentadentate‐Salen) Complexes: Asymmetric Epoxidation with Aqueous Hydrogen Peroxide and Asymmetric Cyclopropanation (salenH₂: N,N′‐bis(salicylidene)ethylene‐1,2‐diamine)

Thermal Dihydrogen Elimination from Cp*₂Yb(4,5-diazafluorene)