α-Wasserstoffeliminierung aus Titan(1-aza-1,3-dien)-Komplexen: Synthese von metallacyclischen Titanalkylidenkomplexen

Kahlert, Steffen; Görls, Helmar; Scholz, Joachim

doi:10.1002/(sici)1521-3757(19980703)110:13/14<1958::aid-ange1958>3.0.co;2-6

Cited by 8 publications

(1 citation statement)

References 47 publications

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“…The reactivities of 2b and comparable derivatives are much lower. 17,18 In addition, owing to spontaneous oligomerization or polymerization, the imines derived from the allyl amines Aa,c−f cannot be used directly as ligands in reductive complexation reactions. In particular, for Ac,e, the C−H bond activation occurs exclusively at the allylic C sp 3 H 2 position.…”

Section: ■ Introductionmentioning

confidence: 99%

Reactions of Secondary Allylamines with Bis(η⁵:η¹-pentafulvene)titanium Complexes: Selective Formation of Monoazabutadiene Titanium Complexes by N–H and C–H Bond Activation

et al. 2017

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The N−H and C−H bond activation reactions at ambient conditions of seven different secondary allyl amines (Aa−g) with bis(η 5 :η 1 -pentafulvene)titanium complexes (1) h a v e b e e n i n v e s t i g a t e d . B i s ( η 5 : η 1adamantylidenepentafulvene)titanium (1a) reacts with Nallylaniline (Aa), N-allylbenzylamine (Ac), N-allyl-tert-butylamine (Ad), N-allylcyclohexylamine (Ae), and N-allyl-2methylaniline (Af) to give the 1-azabutadiene complexes 2a,c−f with high yields. They are the first complexes of the CH 2 -terminated monoazadiene RNCHCHCH 2 . Using bis(η 5 :η 1 -di-p-tolylpentafulvene)titanium (1b), which exhibits a less Brønsted basic C exo center, and Aa, the β-C−H bond activation can be slowed down so much that the agostic interaction between the titanium center and the C−H bond is detectable via NMR measurements at room temperature. In the reactions of the titanium azabutadiene complexes 2a,b and 3a with carbon monoxide a ligand exchange is observed, forming the titanocene dicarbonyls 4a,b.

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Section: ■ Introductionmentioning

confidence: 99%

Reactions of Secondary Allylamines with Bis(η⁵:η¹-pentafulvene)titanium Complexes: Selective Formation of Monoazabutadiene Titanium Complexes by N–H and C–H Bond Activation

et al. 2017

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Reduktion eines 1‐Aza‐1,3‐diens zum 1‐Azabut‐2‐en‐1,4‐diyl‐Dianion: ein ungewöhnlicher Reaktionsverlauf

2003

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Ein überraschendes Zwischenprodukt bei der Reduktion des 1‐Aza‐1,3‐diens 1 durch Lithium ist das Dilithium(hexa‐1,5‐dien‐1,6‐diamid) 2, das durch Dimerisierung des zunächst gebildeten Radikalanions von 1 entsteht. Bei längeren Reaktionszeiten hält die geknüpfte C‐C‐Bindung von 2 dem Alkalimetall jedoch nicht stand und wird reduktiv gespalten. Dabei bildet sich die dunkelrote Dilithium(1‐azabut‐2‐en‐1,4‐diyl)‐Verbindung 3.

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Stereoselective Construction of Acyclic Carbon Chains by a One‐Pot Coupling Process Based on Alkenyloxazoline–Titanium Complexes

et al. 2004

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Oxazoline is known as a versatile functional group in organic synthesis for the activation of substrates and for asymmetric synthesis.[1] Complexation of organic compounds having this group with transition metals may lead to the development of unique synthetic transformations, [2] but an olefin complex such as the one in Scheme 1 (M = metal) [3] has not been investigated. We report here that titanation of alkenyloxazolines proceeds nicely to give novel olefin-titanium complexes (Scheme 1, M = Ti(OiPr) 2 ), which subsequently allow for a diastereoselective multicomponent coupling process and an asymmetric coupling reaction. Treatment of alkenyloxazoline 2[4] with a titanium(ii) alkoxide reagent 1 formed from Ti(OiPr) 4 with two equivalents of iPrMgCl, [5] generates olefin complex 3, [6] which underwent a coupling reaction with 1-octyne (4) to give titanacycle 6 (R = C 6 H 13 ; Scheme 2). Intermediates 3 and 6 were identified by deuteriolysis.[7] The carbon-titanium bond a to the oxazoline (rather than the vinyl-titanium bond) of 6 selectively reacted with the octanal to give, after hydrolytic work-up, a single regioisomer 8 having exclusively an Eolefinic bond. Surprisingly, the crude reaction mixture contained this adduct 8 together with a very small amount of one of the four possible diastereoisomers (d.r. = 96:4) arising from the three consecutive stereogenic centers. Compound 8 could be readily separated from this minor isomer [8] by flash chromatography on silica gel to give a pure sample in 66 % yield. The stereochemistry of 8 was determined (as depicted) by derivatization. [7] A stereochemical course from 2 to 8 is proposed in the Supporting Information. [7] Analogously, the sequential treatment of 2 with silylacetylene 5 and nonanal Scheme 1. Generation of the olefin-metal complex.Scheme 2. Four-component coupling process.

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α-Wasserstoffeliminierung aus Titan(1-aza-1,3-dien)-Komplexen: Synthese von metallacyclischen Titanalkylidenkomplexen

Cited by 8 publications

References 47 publications

Reactions of Secondary Allylamines with Bis(η⁵:η¹-pentafulvene)titanium Complexes: Selective Formation of Monoazabutadiene Titanium Complexes by N–H and C–H Bond Activation

Reactions of Secondary Allylamines with Bis(η⁵:η¹-pentafulvene)titanium Complexes: Selective Formation of Monoazabutadiene Titanium Complexes by N–H and C–H Bond Activation

Reduktion eines 1‐Aza‐1,3‐diens zum 1‐Azabut‐2‐en‐1,4‐diyl‐Dianion: ein ungewöhnlicher Reaktionsverlauf

Stereoselective Construction of Acyclic Carbon Chains by a One‐Pot Coupling Process Based on Alkenyloxazoline–Titanium Complexes

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α-Wasserstoffeliminierung aus Titan(1-aza-1,3-dien)-Komplexen: Synthese von metallacyclischen Titanalkylidenkomplexen

Cited by 8 publications

References 47 publications

Reactions of Secondary Allylamines with Bis(η5:η1-pentafulvene)titanium Complexes: Selective Formation of Monoazabutadiene Titanium Complexes by N–H and C–H Bond Activation

Reactions of Secondary Allylamines with Bis(η5:η1-pentafulvene)titanium Complexes: Selective Formation of Monoazabutadiene Titanium Complexes by N–H and C–H Bond Activation

Reduktion eines 1‐Aza‐1,3‐diens zum 1‐Azabut‐2‐en‐1,4‐diyl‐Dianion: ein ungewöhnlicher Reaktionsverlauf

Stereoselective Construction of Acyclic Carbon Chains by a One‐Pot Coupling Process Based on Alkenyloxazoline–Titanium Complexes

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Reactions of Secondary Allylamines with Bis(η⁵:η¹-pentafulvene)titanium Complexes: Selective Formation of Monoazabutadiene Titanium Complexes by N–H and C–H Bond Activation

Reactions of Secondary Allylamines with Bis(η⁵:η¹-pentafulvene)titanium Complexes: Selective Formation of Monoazabutadiene Titanium Complexes by N–H and C–H Bond Activation