Mechanism of Insertion of Carbodiimides into the Zr−C Bonds of Zirconaaziridines. Formation of α-Amino Amidines

Tunge, Jon A.; Czerwinski, Curtis J.; Gately, and Daniel A.; Norton, Jack R.

doi:10.1021/om000768s

Cited by 34 publications

(17 citation statements)

References 18 publications

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“…The crude product was purified by column chromatography. The obtained analytical data are in agreement with literature reports [26,54,[69][70][71][72][73][74][75][76][77][78][79][80]. …”

Section: Discussionsupporting

confidence: 91%

Practical One-Pot Synthesis of Secondary Amines by Zinc-Catalyzed Reductive Amination

Enthaler

2010

Catal Lett

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In the present study, the zinc-catalyzed reductive amination of various aldehydes has been examined in detail. Simple zinc(II) triflate was applied as hydrosilylation catalyst for the reduction of the in situ formed imine by condensation of an aldehyde with an amine. Using a practical Lewis acid catalyst and PMHS [poly(methylhydrosiloxane)] as cheap hydride source excellent yields and a broad functional group tolerance were achieved.

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“…The crude product was purified by column chromatography. The obtained analytical data are in agreement with literature reports [26,54,[69][70][71][72][73][74][75][76][77][78][79][80]. …”

Section: Discussionsupporting

confidence: 91%

Practical One-Pot Synthesis of Secondary Amines by Zinc-Catalyzed Reductive Amination

Enthaler

2010

Catal Lett

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“…72 Because of the low quality of the X-ray structure solution, we abandon a detailed discussion of further bond length and angles. However, we also synthesized the comparable complex 13 with a slightly modified ligand system starting from Cp*TiCl 3 (12) instead of Cp 2 TiCl 2 (2). Reacting 12 with ketimine 4 in the presence of Mg as reducing agent, a color change from orange red to dark violet occurred.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…All solvents and reagents were obtained from commercial suppliers and used as received unless otherwise noted. N-(4-Methylbenzylidene)aniline (3) was prepared according to the procedure of Ramsden and Nongkunsarn, 83 and Cp 2 Ti(η 2 -BTMSA) (1) 59 was synthesized according to a literature procedure as well as Cp*TiCl 3 (12). 84 The used solvents, except within the synthesis of 3, were dried with common drying agents and freshly distilled under nitrogen atmosphere prior to use.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Aromatic Imines in the Titanocene Coordination Sphere—Titanaaziridine vs 1-Aza-2-titanacyclopent-4-ene Structures

et al. 2014

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Two independent synthetic routes to η2-imine titanocene complexes were developed. On one hand side, ligand exchange reactions of bis(trimethylsilyl)acetylene by (p-Tolyl)HCNPh (3) employing the Rosenthal reagent Cp2Ti{η2-C2(SiMe3)2} (1) lead to Cp2Ti{η2-(p-Tolyl)CHNPh} (5), exhibiting a titanaaziridine structure. On the other hand, the direct reductive complexation of 3 by using Cp2TiCl2 (2) and Mg as reducing agent leads also to 5, one of the rare known titanoceneaziridines without additional ligands. By using the ketimine (p-Tolyl)2CNPh (4) instead of the aldimine 3, an unexpected coordination mode was found by X-ray diffraction, exhibiting an azatitanacyclopent-4-ene structure involving one tolyl fragment. In such a way, via the reductive complexation of 4, employing 2 or Cp*TiCl3 (12), the 1-aza-2-titanacyclopent-4-ene complexes 6 and 13 are formed. Density functional calculations at the M06-2X level identify these new complexes 6 and 13 as 1-aza-2-titanacyclopent-4-enes, in agreement with an analysis based on the experimental structural parameters. A theoretical study of the bonding between the titanocene fragment and the imine ligand reveals that steric factors are more pronounced for titanaaziridines and disfavor their formation compared to azatitanacyclopentenes. This provides a rationalization for the preferred formation of titanoceneaziridines in the case of aldimine ligands and azatitanacyclopentenes when ketimines are applied. Whereas titanoceneaziridine 5 undergoes insertion reactions into the Ti–C carbon σ-bond with aldehydes, ketones, or carbodiimides to the five-membered titanacycles 20 and 21, complex 6 appears to be inert in comparable reactions.

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“…Alkyl or amido complexes of main group, lanthanide, or early-transition elements react with carbodiimides giving amidininato [32][33][34][35] or guanidinato derivatives, [33,34,[36][37][38][39] respectively; some of these have found applications. [35,37,40] Insertion reactions of carbodiimides into an M À C (M= metal) of other organometallic compounds [41] or into an M À H bond [42] have also been reported. Carbodiimide insertion into the Abstract: Complexes [Pd(C 6 OTf.…”

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confidence: 99%

Reactivity of ortho‐Substituted Aryl–Palladium Complexes towards Carbodiimides, Isothiocyanates, Nitriles, and Cyanamides

Vicente

Abad

López-Sáez

et al. 2009

Chemistry A European J

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Complexes [Pd(C(6)H(3)XH-2-R'-5)Y(N;N)] (X=O, NH; Y=Br, I; R'=H, NO(2); N;N=N,N,N',N'-tetramethylethylenediamine (tmeda), 2,2'-bipyridine (bpy), 4,4'-di-tert-butyl-2,2'-bipyridine (dtbbpy)) react with RN=C=E (E=NR, S) or RC identical withN (R=alkyl, aryl, NR''(2)) and TlOTf (OTf=CF(3)SO(3)) to give, respectively, 1) products of the insertion of the C=E group into the C--Pd bond, protonation of the N atom, and coordination of X to Pd, [Pd{kappa(2)-X,E-(XC(6)H(3){EC(NHR)}-2-R'-4)}(N;N)]OTf or [Pd(kappa(2)-X,N-{ZC(6)H(3)(NH=CR)-2-R'-4})(N;N)]OTf, or products of the coordination of carbodiimides and OH addition, [Pd{kappa(2)-C,N-(C(6)H(4){OC(NR)}NHR-2)}(bpy)]OTf; or 2) products of the insertion of the C identical withN group to Pd and N-protonation, [Pd(kappa(2)-X,N-{XC(6)H(3)(NH=CR)-2-R'-4})(N;N)]OTf.

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Mechanism of Insertion of Carbodiimides into the Zr−C Bonds of Zirconaaziridines. Formation of α-Amino Amidines

Cited by 34 publications

References 18 publications

Practical One-Pot Synthesis of Secondary Amines by Zinc-Catalyzed Reductive Amination

Practical One-Pot Synthesis of Secondary Amines by Zinc-Catalyzed Reductive Amination

Aromatic Imines in the Titanocene Coordination Sphere—Titanaaziridine vs 1-Aza-2-titanacyclopent-4-ene Structures

Reactivity of ortho‐Substituted Aryl–Palladium Complexes towards Carbodiimides, Isothiocyanates, Nitriles, and Cyanamides

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