The synthesis of NH aldimines and derivatives by spontaneous and base-catalysed decomposition of oxaziridines

Boyd, Derek R.; Coulter, Peter B.; Hamilton, Robert; Thompson, Norris T.; Sharma, Narain D.; Stubbs, Michael E.

doi:10.1039/p19850002123

Cited by 18 publications

(7 citation statements)

References 3 publications

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“…The [(PCN)Rh(N 2 )] complex 5 exhibits reactivity similar to that of 1 . Upon reaction with benzalazine quantitative formation of the benzonitrile complex 6 (Table 1) was observed together with formation of free imine PhCHNH (Scheme ) 13. This imine is unstable and rapidly decomposes (10 min at room temperature), in agreement with literature data 14.…”

Section: Methodssupporting

confidence: 87%

Novel Azine Reactivity: Facile NN Bond Cleavage, CH Activation, and NN Coupling Mediated by Rh^I

et al. 2003

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Azines (R 2 C¼NÀN¼CR 2 ) are very useful compounds. For example, they undergo unusual [1,3] dipolar cycloaddition reactions (the crisscross addition) with dienophiles, which provide a convenient route to five-membered rings. [1] They also participate in [3þ2] cycloaddition reactions as an ene fragment. [2] Applications of azines include possible nonlinear optical materials [3] and conducting polymers (polyazines). [4] Relevant to dinitrogen fixation, the formation of azines by metal-mediated functionalization of N 2 was demonstrated. [5] Azine derivatives display important biological properties and are of importance for drug development. [6] Complexes of titanium, [7] zirconium, [7c] cobalt, [7c] uranium, [8] and iron [9] are capable of cleaving the N À N bond in azines. In all the reported cases, the azine NÀN bond is cleaved symmetrically forming two imide units, ÀN¼CR 2 , coordinated to a metal center. No metal-complex-catalyzed reactions were reported. Herein we report a novel type of azine reactivity, the rhodium-promoted catalytic "nonsymmetrical" NÀN bond cleavage accompanied by C À H activation, which leads to an imine and benzonitrile. This is the first metal-promoted nonsymmetric cleavage of the NÀN bond in an azine [10] and the first metal-catalyzed NÀN activation in an azine.When a toluene solution of the PCP-pincer rhodium complex 1 [11] was treated with one equivalent of benzalazine at À30 8C, three complexes were formed (Scheme 1). One of them, tentatively identified by NMR spectroscopy as the [(PCP)Rh(benzalazine)] complex 2 (precedents exist for azine complexes [7] ), is an intermediate, which converts into [*] Prof.

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Section: Methodssupporting

confidence: 87%

Novel Azine Reactivity: Facile NN Bond Cleavage, CH Activation, and NN Coupling Mediated by Rh^I

et al. 2003

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“…[12] NH aldimines have been proposed as intermediates in many reactions, and their highly unstable nature is well documented. [13][14][15] The first evidence for the existence of NH aldimines containing a saturated alkyl group was reported in 1982, [14] and PhCH=NH was identified in 1985 by using NMR studies in C 6 D 5 CD 3 at À70 8C and by the reaction with methylamine to yield N-benzylidenemethylamine through transimination. [13] Only two NH aldimines have been isolated, in both cases at low temperatures.…”

Section: Introductionmentioning

confidence: 99%

Deamination of the Amino Acid Fragment in Imine Metallacycles: Unexpected Synthesis of an NH‐Aldimine Organometallic Compound

Albert

Cadena

González

et al. 2006

Chemistry A European J

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We report that the action of Lewis bases, such as triphenylphosphine, pyridine, or trimethylamine, on imine metallacycles derived from amino acids leads to the formation of the first organometallic compound of an NH aldimine, a highly reactive organic species, and the corresponding alpha-ketoester, in a deamination reaction that mimics the metabolism of alpha-amino acids. The synthesis of different cyclopalladated compounds by a reaction between palladium acetate and the Schiff bases 2,4,6-Me(3)C(6)H(2)CH=NCH(R(1))COOR(2) (R(1) = CH(2)Ph, R(2) = Et and R(1) = Ph, R(2) = Me) is also reported.

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“…The successful dehydrogenation of primary amines to free nitriles offered the prospect of also producing imines from −NH 2 -substituted secondary carbon centers. Unfortunately the limited stability of imines formed from primary amines has hampered this approach . Treatment of 1-H 2 with 10 equiv of sec -butylamine and 20 equiv of TBE at 185 °C in mesitylene- d 12 for 48 h afforded significant quantities of ammonia (∼60% based on the amine), TBA, and several unidentified organic species.…”

Section: Resultsmentioning

confidence: 99%

Kinetics and Mechanism of Iridium-Catalyzed Dehydrogenation of Primary Amines to Nitriles

Bernskoetter

Brookhart

2008

Organometallics

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A family of primary amines has been catalytically dehydrogenated to nitriles by [C6H3-2,6-(OP t Bu2)2]IrH2 using tert-butylethylene as a hydrogen acceptor. The catalytic mechanism has been investigated by a series of kinetic and isotopic labeling experiments, in addition to the isolation of intermediates along the reaction pathway. The turnover frequency exhibits a first-order dependence on the concentration of amine, an inverse first-order dependence on nitrile, and a zero-order dependence on tert-butylethylene. The mechanism of amine dehydrogenation is proposed to proceed from an iridium(I) nitrile complex, the catalyst resting state, via two preturnover limiting equilibria, followed by a slow β-hydride elimination event from a transient iridium(III) amido hydride species. Measuring rate constants for the stoichiometric dehydrogenation of isobutylamine over a 41 °C temperature range established activation parameters for β-hydride elimination of ΔH ⧧ 24.8(9) kcal/mol and ΔS ⧧ = −10(2) eu. Dehydrogenation of a series of para-substituted benzyl amines indicated enhanced conversions to nitriles for substrates bearing electron-donating substituents.

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The synthesis of NH aldimines and derivatives by spontaneous and base-catalysed decomposition of oxaziridines

Cited by 18 publications

References 3 publications

Novel Azine Reactivity: Facile NN Bond Cleavage, CH Activation, and NN Coupling Mediated by Rh^I

Novel Azine Reactivity: Facile NN Bond Cleavage, CH Activation, and NN Coupling Mediated by Rh^I

Deamination of the Amino Acid Fragment in Imine Metallacycles: Unexpected Synthesis of an NH‐Aldimine Organometallic Compound

Kinetics and Mechanism of Iridium-Catalyzed Dehydrogenation of Primary Amines to Nitriles

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The synthesis of NH aldimines and derivatives by spontaneous and base-catalysed decomposition of oxaziridines

Cited by 18 publications

References 3 publications

Novel Azine Reactivity: Facile NN Bond Cleavage, CH Activation, and NN Coupling Mediated by RhI

Novel Azine Reactivity: Facile NN Bond Cleavage, CH Activation, and NN Coupling Mediated by RhI

Deamination of the Amino Acid Fragment in Imine Metallacycles: Unexpected Synthesis of an NH‐Aldimine Organometallic Compound

Kinetics and Mechanism of Iridium-Catalyzed Dehydrogenation of Primary Amines to Nitriles

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Novel Azine Reactivity: Facile NN Bond Cleavage, CH Activation, and NN Coupling Mediated by Rh^I

Novel Azine Reactivity: Facile NN Bond Cleavage, CH Activation, and NN Coupling Mediated by Rh^I