Imine Insertion into a Late Metal−Carbon Bond To Form a Stable Amido Complex

Krug, Christopher; Hartwig, John F.

doi:10.1021/ja038819a

Cited by 35 publications

(18 citation statements)

References 13 publications

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“…23,24 Given this useful reactivity, many ligand systems based on a,b-unsaturated ketones, esters and acetophenones have been explored in recent years. [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] Our research group has been interested in the reactivity of related ortho-metallated imines. Ortho-metallation of acetophenone imines with late metals is readily accessible by C-H activation of the aryl moiety, and this type of reaction allows for the synthesis of metal hydrides with potential applications in C-C bond coupling reactions.…”

Section: Introductionmentioning

confidence: 99%

Mono-anionic acetophenone imine ligands: synthesis, ortho-lithiation and first examples of group (v) metal complexes

et al. 2009

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A series of niobium and tantalum imido complexes with mono-anionic ortho-metallated acetophenone imine ligands have been prepared and characterized using NMR spectroscopy, mass spectrometry and elemental analysis. These low symmetry complexes are produced with only one or two structural isomers in all cases and display interesting correlations between the steric bulk of the ligands employed and the isomers formed. Crystal structures of several new niobium and tantalum complexes are presented as confirmation of the connectivity in these structural isomers.

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Section: Introductionmentioning

confidence: 99%

Mono-anionic acetophenone imine ligands: synthesis, ortho-lithiation and first examples of group (v) metal complexes

et al. 2009

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“…For the asymmetric 1,4‐addition to α,β‐unsaturated ketones,15 esters,16 and alkenylphosphonates17 catalyzed by a rhodium complex coordinated with ( S )‐binap, we have proposed stereorecognition models that successfully rationalize the absolute configuration of the products. By applying this type of model to the present reaction of N ‐alkylidene sulfonamides,18 it is evident that the enantioface of the imine is recognized by steric repulsions between one of the phenyl rings on the diphenylphosphino group and the aromatic ring on the arene sulfonamide (Scheme ). Steric tuning of the arene sulfonamide moiety by introduction of sterically bulky groups onto the aromatic ring actually brought about enhancement of the enantioselectivity to an acceptable level.…”

Section: Methodsmentioning

confidence: 99%

Asymmetric Synthesis of Diarylmethyl Amines by Rhodium‐Catalyzed Asymmetric Addition of Aryl Titanium Reagents to Imines

2004

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Asymmetric synthesis of diarylmethyl amines has attracted growing attention owing to their importance in biological activity.[1] Among several methods for performing the asymmetric synthesis, [2,3] catalytic asymmetric addition of aryl metal reagents to imine derivatives seems to be most promising, provided that both high enantioselectivity and high catalytic activity are realized.[4] After our publication on the rhodium-catalyzed asymmetric addition of aryl stannanes to N-sulfonylimines, [5] two reports appeared on catalytic asymmetric arylation: 1) Bräse, Bolm, and co-workers described the addition of a phenylzinc reagent to masked Nformylimines in the presence of a chiral ketimine catalyst, [6] and 2) Tomioka illustrated the rhodium-catalyzed addition of aryl boroxines to N-tosylimines in which high enantioselectivity was observed for sterically tuned aryl imines.[7] Herein we report another rhodium-catalyzed asymmetric arylation in which the addition of aryl titanium reagents to sulfonylimines proceeds with high enantioselectivity under mild conditions (20 8C, 1 h) to give diarylmethyl amines with up to 96 % ee.During our studies on rhodium-catalyzed asymmetric 1,4-additions to a,b-unsaturated ketones, [8] we found that the phenyltitanium reagent PhTi(OiPr) 3 is highly reactive toward transmetalation and forms a phenyl-rhodium bond. In the presence of a rhodium/(S)-binap catalyst in THF at 20 8C, the catalytic 1,4-addition gives titanium enolates as 1,4-addition products with high enantioselectivity.[9] Under similar reaction conditions (Scheme 1), the addition of PhTi(OiPr) 3 [10] (4 a) to N-tosylarylimine 1 a, which was prepared from 4-trifluoromethylbenzaldehyde and 4-toluenesulfonamide, [11] took place rapidly to give the tosylamide of diarylmethyl amine 5 aa after aqueous workup, unfortunately with only 28 % ee (Table 1, entry 1). The use of (S)-H 8 -binap [12] and (S)-segphos [13] in place of (S)-binap [14] improved the enantioselectivity up to 43 % and 76 % ee, respectively (Table 1, entries 4 and 6). The relatively narrow dihedral angle of the biaryl bisphosphine ligand segphos [14] is considered to exert a positive influence on the enantioselectivity in the present

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“…Experimentally, Hartwig and co-workers reported that the arylrhodium complex (dppe)Rh(pyridine)(p-tol) undergoes an insertion reaction with the N-aryl aldimine (p-tol)-CH=N(C 6 H 4p-CO 2 Me) to yield a stable amido complex, which is the reversible process of b-phenyl elimination. 26 The experimental observation is not expected because of the highly endergonic nature of the reaction discussed above. In the model calculations discussed above, we used Me as the substituent at N of the aldimine substrate.…”

Section: B-allyl and B-vinyl Eliminationsmentioning

confidence: 99%

Theoretical studies on β-aryl elimination from Rh(i) complexes

Xue

Lin

2009

Dalton Trans.

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Beta-aryl eliminations in a series of rhodium alkoxide, alkyl and amido complexes were investigated with the aid of density function theory calculations at the Becke3LYP level. Our calculation results indicate that the typical barriers for beta-aryl eliminations are in the range of 20-25 kcal mol(-1). For comparison, beta-allyl and beta-vinyl eliminations were also studied. It was found that beta-allyl elimination is noticeably more favourable than beta-aryl elimination while beta-vinyl elimination is only slightly more favourable. The reversible reactions of beta-aryl elimination correspond to the insertion reactions into a metal-aryl bond. On the basis of the thermochemistry calculated, we discussed the factors influencing the thermodynamic preference of the beta-aryl elimination vs. insertion (the reversible process). The results indicate that the preference can be switched when different substrates and ligands are used.

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Imine Insertion into a Late Metal−Carbon Bond To Form a Stable Amido Complex

Cited by 35 publications

References 13 publications

Mono-anionic acetophenone imine ligands: synthesis, ortho-lithiation and first examples of group (v) metal complexes

Mono-anionic acetophenone imine ligands: synthesis, ortho-lithiation and first examples of group (v) metal complexes

Asymmetric Synthesis of Diarylmethyl Amines by Rhodium‐Catalyzed Asymmetric Addition of Aryl Titanium Reagents to Imines

Theoretical studies on β-aryl elimination from Rh(i) complexes

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