Addition of Carbon Nucleophiles to Tricarbonylchromium Complexes of 1,2‐Dihydrocyclobutabenzene, Indane, 1,2,3,4‐Tetrahydronaphtbalene and <i>ortho</i>‐Xylene

Kündig, E. Peter; Grivet, Chantal; Wenger, Eric; Bérnardinelli, Gerald; Williams, Alan F.

doi:10.1002/hlca.19910740836

Cited by 30 publications

(10 citation statements)

References 57 publications

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“…from À 7 to 158, with the exception of 6 where t 43.78. This distortion can be attributed to the presence of the two vicinal Me substituents of the o-xylene and has also been observed in [Cr(h 6 -oxylene)(CO) 3 ] [32]. The symmetrically substituted arene complexes 5, 17, and 20 exhibit much smaller distortions.…”

Section: Methodsmentioning

confidence: 70%

New Chromium Enolates

Kündig

Bérnardinelli

Kondratenko

et al. 2003

Helvetica Chimica Acta

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Three new (?2-acrylate)(?6-arene)dicarbonylchromium complexes are reported. They were obtained either by CO/acrylate exchange in [Cr(?6-benzene)(CO)3] (1) via the photolytically generated ?2-cyclooctene intermediate or by arene exchange in [Cr(?2-methyl acrylate)(?6-benzene)(CO)2] (3) (Scheme 1). On crystallization, [Cr(?2-methyl acrylate)(?6-o-xylene)(CO)2] (5) underwent partial resolution. The degree of this resolution was analyzed via X-ray crystal-structure determination (Fig. 1) and was correlated to the CD spectra in solution (Fig. 6), thus allowing the assignment of the absolute configuration. The reaction of [Cr(?2-acrylate)(?6-benzene)(CO)2] complexes with cyclopentad-1,3-diene or 1H-indene afforded new (?6-cyclopenta-2,4-dien-1-yl)- or (?6-1H-inden-1-yl)(?3-oxaallyl)chromium complexes (Scheme 2). A mechanism is proposed that involves arene-ligand substitution by the diene ligand, initiated by haptotropic rearrangement of the acrylate from a ?2- to a ?4-coordination mode, followed by hydride migration from the diene to the acrylate (Scheme 3). An X-ray crystal-structure determination of [Cr(CO)2(?5-1H-inden-1-yl){?3-CH(CH2CF3)C(O)OEt}] (8) reveals a metal enolate that is best described as ?3-oxaallyl species (Fig. 2). A shorter, more-efficient route to the [Cr(?5-1H-inden-1-yl)(?3-oxaallyl)] complexes was devised via the reaction of [Cr(CO)2(?2-cyclooctene)(?6-1H-indene)] with methyl acrylate (Scheme 4)

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Section: Methodsmentioning

confidence: 70%

New Chromium Enolates

Kündig

Bérnardinelli

Kondratenko

et al. 2003

Helvetica Chimica Acta

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“…However, with two identical substituents, the addition is preferred in the adjacent position [2]. For example, with the complex of benzocyclobutene (45), six carbon nucleophiles were tested and each gave addition exclusively at C-3 [2,115]. With the complex of indane (46), selective addition at C-3 was observed with dithianyl anions, but cyano-stabilized anions gave up to 20% of the isomeric product from addition at C-4.…”

Section: Regioselectivitymentioning

confidence: 99%

(Arene)Cr(CO)3 Complexes: Aromatic Nucleophilic Substitution

Semmelhack

Chlenov

2004

Topics in Organometallic Chemistry

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Transition metals coordinated to the pi system of arenes function as strong electronwithdrawing groups and favor nucleophilic addition to the arene to give cyclohexadienyl-metal complexes. The regioselectivity of addition is influenced in subtle and indirect ways, compared to the powerful effect on both reactivity and regioselectivity of electron-withdrawing groups attached to the sigma bond system of the arene. The intermediate cyclohexadienyl complexes can be processed in several ways, leading to several distinct synthesis methods. Useful reactivity is known for several metal systems and each is discussed for specific reaction types. The presence of a fluoro or chloro substituent on the arene allows an effective analog of classical S N Ar reactivity, with a wide range of nucleophiles including simple amines, alkoxides, and carbon anions. Another general process is the addition/protonation protocol, where a hydrogen substituent on the arene is replaced by a nucleophile. This opens new questions of regioselectivity since the typical arene ligand has several hydrogens which are candidates for substitution. The formation of five-and six-membered rings by both general mechanisms are known. Less general indirect mechanisms (e.g., tele substitution) have also been defined.

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“…Many derivatives are known and have been used to prepare theoretically interesting compounds or natural products, [17][18][19][20][21][22][23][24][25][26][27][28][29] and a number of theoretical calculations have been carried out in this field. [30][31][32][33][34][35][36][37][38][39][40][41] Another difference between 5 and 27 is the fact that the ligand of 5 is an anion whereas benzocyclobutene is electroneutral. In neutral complexes of type 5 this means that there is considerable Coulomb interaction between the bicyclic ligand in 5 and the metal -presumably one reason for which it was possible to heat 17 up to 200°C without decomplexation.…”

Section: Benzocyclobutene Complexesmentioning

confidence: 99%

π Complexes with Annellated Cyclobutene Rings: Bicyclo[3.2.0]heptadienyl Anion and Benzocyclobutene as Ligands for Transition Metals

Butenschön¹

1999

Synlett

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As was first found on the basis of DSC measurements, bicyclo[3.2.0]heptadienyl cobalt complex 17 undergoes a ring opening -cycloaddition sequence at high temperature with formation of ring expansion products. Benzocyclobutene complexes react in a similar way only in one case. However, deprotonation of benzocyclobutenol complex endo-31 results in a dramatic decrease of the ring opening temperature and allows corresponding [4+2] cycloaddition reactions at low temperature. Benzocyclobutenedione complex 74 shows interesting structural features, its fragmentation in the mass spectrometer leads to a η 6 coordinated benzyne chromium cation. Addition of vinylmetal reagents induces a dianionic oxy-Cope rearrangement at -78°C, the first case of such a reaction at such mild reaction conditions. Products are benzannellated cyclooctenediones and their intramolecular aldol adducts, which are obtained with very high diastereoselectivity.

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Addition of Carbon Nucleophiles to Tricarbonylchromium Complexes of 1,2‐Dihydrocyclobutabenzene, Indane, 1,2,3,4‐Tetrahydronaphtbalene and ortho‐Xylene

Cited by 30 publications

References 57 publications

New Chromium Enolates

New Chromium Enolates

(Arene)Cr(CO)3 Complexes: Aromatic Nucleophilic Substitution

π Complexes with Annellated Cyclobutene Rings: Bicyclo[3.2.0]heptadienyl Anion and Benzocyclobutene as Ligands for Transition Metals

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