Cycloaddition of aromatic imines to a ruthenium butatrienylidene complex: synthesis of 4-ethynylquinoline and 1-azabuta-1,3-diene complexes

Bruce, Michael I.; Hinterding, Peter; Ke, Mingzhe; Low, Paul J.; Skelton, Brian W.; White, Allan H.

doi:10.1039/a700663b

Cited by 41 publications

(32 citation statements)

References 4 publications

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“…In this context, it should be noted that EHT-MO calculations on the model compound [Ru(η 5 -C 5 H 5 )(CCCH 2 )(CO)(PH 3 )] + indicate that 31% of the LUMO of the complex is located on the C γ atom of the allenylidene ligand . A similar mechanism has been proposed for the cycloaddition of aromatic imines to the C γ −C δ double bond of the butatrienylidene ligand of the cation [Ru(η 5 -C 5 H 5 )(CCCCH 2 )(PPh 3 ) 2 ] + …”

Section: Resultsmentioning

confidence: 67%

Allenylidene Ligand of [Ru(η⁵-C₅H₅)(CCCPh₂)(CO)(PPrⁱ₃)]BF₄ as Entry to Novel Unsaturated η¹-Carbon Ligands Containing Azetidine and Hexahydroquinoline Skeletons

et al. 1999

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The allenylidene complex [Ru(η5-C5H5)(CCCPh2)(CO)(PPri 3)]BF4 (1) reacts with dicyclohexylcarbodiimide to give the iminiumazetidinylidenemethyl complex (2), as a 4:1 mixture of isomers Z (2a) and E (2b). The structure of 2a was determined by an X-ray investigation, revealing a Ru−C distance of 2.070(4) Å. Treatment of the isomeric mixture of 2 with sodium methoxide in tetrahydrofuran at room temperature affords the iminoazetidinylidenemethyl complex (6), which reacts with HBF4·OEt2 to give (7), as a result of the protonation of the exocyclic nitrogen atom of the unsaturated η1-carbon ligand of 6. In the solid state and in solution at low temperature, complex 7 is stable. However, in solution at room temperature, complex 7 evolves into (8), which reacts with sodium methoxide in tetrahydrofuran at room temperature to give the hexahydroquinolinylidenemethyl complex (9), as a result of the deprotonation of the endocyclic nitrogen atom of 8. The structure of 9 was also determined by an X-ray investigation, revealing, in this case, a Ru−C distance of 2.113(4) Å. The formation of the azetidine and hexahydroquinoline skeletons of the ligands of these compounds is discussed.

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Section: Resultsmentioning

confidence: 67%

Allenylidene Ligand of [Ru(η⁵-C₅H₅)(CCCPh₂)(CO)(PPrⁱ₃)]BF₄ as Entry to Novel Unsaturated η¹-Carbon Ligands Containing Azetidine and Hexahydroquinoline Skeletons

et al. 1999

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“…Selegue generated a first example by addition of trifluoroacetic acid anhydride to a coordinated alkynyl ketone . A different approach was utilized by Bruce and Winter, who applied the well-known Ru-mediated terminal alkyne to vinylidene tautomerization 4a, to butadiyne (or diacetylene) as the conceptionally simplest diyne derivative. More recently, this protocol has been applied to other terminal diynes RC 4 H (R = Ph, SiMe 3 ).…”

Section: Introductionmentioning

confidence: 99%

Trapping of a Ruthenium−Butatrienylidene Intermediate by Tertiary Amines. 2-Ammoniobutenynyl Complexes

Winter

Hornung

1999

Organometallics

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2-Ammoniobutenynyl Ru-complexes trans-[Cl(dppm) 2 Ru-CtC-C(NR 2 R′)dCH 2 ] + PF 6 -(3ag) have been prepared in a one-pot procedure from cis-[RuCl 2 (dppm) 2 ], excess butadiyne, and various tertairy amines, whereas 4-(dimethylamino)pyridine binds to the unsaturated carbon ligand via the pyridine nitrogen to give 3h. These results may be rationalized by envoking the butatrienylidene complex trans-[Cl(dppm) 2 RudCdCdCdCH 2 ] + as the reactive intermediate. Amine complexes cis-[Ru(dppm) 2 Cl(NR 2 R′)] + are frequently formed as side products and the 4-dimethylaminopyridine derivative cis-[Ru(dppm) 2 Cl(4-DMAP)] + was obtained in high yield in the absence of butadiyne but under otherwise identical reaction conditions. Complexes 3 have been characterized by various spectroscopic and electrochemical techniques including cyclic and square wave voltammetry and, in the case of the NEt 3 derivative 3a, also by X-ray crystallography. Most complexes 3 undergo a fully reversible one-electron oxidation at half-wave potentials that depend on the amine substituent. This provides evidence for delocalization over the conjugated C 3 bridge. EPR spectroscopic investigations of the oxidized forms of the NEt 3 and PhCH 2 NMe 2 derived complexes 3a and 3f point to Ru-centered radical dications. The irreversible reduction of complexes 3 occurs in two closely spaced, poorly defined waves and ultimately releases the respective free amine, which itself is reactive toward the Ru(III) oxidation product. Following the oxidation of 3a and 3f by UV/vis and IR spectroelectrochemistry revealed a blue shift of the prominent absorption band and a bleaching of the CtC stretch.

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“…The reactions of the C 4 H 2 ligand present in cationic [Ru]NCNCNCNCH 2 + intermediates include the addition of aprotic nucleophiles to the electrophilic C g 3,4 and the addition of protic nucleophiles to the terminal double bond generating methyl substituted allenylidene complexes. Some interesting cycloaddition/cycloreversion chemistry 5 as well as an unusual Aza-Cope rearrangement following the addition of allyl substituted tertiary amines were also reported. 4 We have initiated a program aimed at synthesizing novel heteroatom substituted Ru-allenylidene complexes [Ru]NC NCNC(ER n )RA + from butatrienylidene precursors trans-[ClRu(L 2 ) 2 NCNCNCNCH 2 ] + (L 2 = chelating diphosphine) and investigating their spectroscopic and electrochemical properties as a function of the heteroatom and the oxidation state of Ru.…”

mentioning

confidence: 99%

A Ru-allenylidene complex with an appended redox-active substituent: spectroscopic characterization of three oxidation states†

Winter¹

1998

Chem. Commun.

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Cycloaddition of aromatic imines to a ruthenium butatrienylidene complex: synthesis of 4-ethynylquinoline and 1-azabuta-1,3-diene complexes

Cited by 41 publications

References 4 publications

Allenylidene Ligand of [Ru(η⁵-C₅H₅)(CCCPh₂)(CO)(PPrⁱ₃)]BF₄ as Entry to Novel Unsaturated η¹-Carbon Ligands Containing Azetidine and Hexahydroquinoline Skeletons

Allenylidene Ligand of [Ru(η⁵-C₅H₅)(CCCPh₂)(CO)(PPrⁱ₃)]BF₄ as Entry to Novel Unsaturated η¹-Carbon Ligands Containing Azetidine and Hexahydroquinoline Skeletons

Trapping of a Ruthenium−Butatrienylidene Intermediate by Tertiary Amines. 2-Ammoniobutenynyl Complexes

A Ru-allenylidene complex with an appended redox-active substituent: spectroscopic characterization of three oxidation states†

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Cycloaddition of aromatic imines to a ruthenium butatrienylidene complex: synthesis of 4-ethynylquinoline and 1-azabuta-1,3-diene complexes

Cited by 41 publications

References 4 publications

Allenylidene Ligand of [Ru(η5-C5H5)(CCCPh2)(CO)(PPri3)]BF4 as Entry to Novel Unsaturated η1-Carbon Ligands Containing Azetidine and Hexahydroquinoline Skeletons

Allenylidene Ligand of [Ru(η5-C5H5)(CCCPh2)(CO)(PPri3)]BF4 as Entry to Novel Unsaturated η1-Carbon Ligands Containing Azetidine and Hexahydroquinoline Skeletons

Trapping of a Ruthenium−Butatrienylidene Intermediate by Tertiary Amines. 2-Ammoniobutenynyl Complexes

A Ru-allenylidene complex with an appended redox-active substituent: spectroscopic characterization of three oxidation states†

Contact Info

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Allenylidene Ligand of [Ru(η⁵-C₅H₅)(CCCPh₂)(CO)(PPrⁱ₃)]BF₄ as Entry to Novel Unsaturated η¹-Carbon Ligands Containing Azetidine and Hexahydroquinoline Skeletons

Allenylidene Ligand of [Ru(η⁵-C₅H₅)(CCCPh₂)(CO)(PPrⁱ₃)]BF₄ as Entry to Novel Unsaturated η¹-Carbon Ligands Containing Azetidine and Hexahydroquinoline Skeletons