Heteropolymetallic Complex Syntheses by Reiterative Nucleophilic Additions of Lithiated (η<sup>6</sup>-Arene)tricarbonylchromium Compounds to Cationic (η<sup>6</sup>-Benzene)manganese Complexes

Renard, Christophe; Valentic, Raphael; Rose‐Munch, Françoise; Rose, Éric; Vaisserman, Jacqueline

doi:10.1021/om970900x

Cited by 24 publications

(7 citation statements)

References 47 publications

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“…The increase of the bulkiness of alkyl radicals inhibited the ortho-addition, and thus only meta-and para-addition products could be detected in the reaction of tert-butyl radical (entry 6, Table 3). The above regioselectivity pattern is similar to that in the nucleophilic addition reactions with Grignard reagents [14][15][16][17][18][19][20][21][22][23] or organolithium reagents 16,[19][20][21][24][25] but slightly better than that in the reactions of 1b with alkylmercury halides. 5c To further demonstrate the advantage of the above methodology, we prepared alkyl iodides 7a-e bearing various functional groups and carried out their reactions with complex 1a (Table 4).…”

Section: Resultssupporting

confidence: 52%

“…The results in Table clearly demonstrated the advantage of the above radical methodology over the conventional ionic processes. ,,− Although the addition of functionalized nucleophiles to arene-Mn(CO) 3 + complexes gave the corresponding products in reasonable to high yields, stabilized carbanions such as ketone enolates or α-ester carbanions were usually employed. ,,− On the other hand, the nucleophilic addition of the functionalized zinc reagent IZn(CH 2 ) 2 CO 2 Et or IZn(CH 2 ) 2 CN to complex 1a afforded the α-alkylated product rather than the expected β-alkylated product because of deprotonation of the acidic proton α to the ester or cyano group as reported by Yeh and co-workers . A Grignard reagent equivalent to 7a or 7b would be impossible. − A nucleophilic anionic reagent equivalent to 7d would result in β-elimination to give cyclohexene. , Moreover, the ionic processes require strict anhydrous conditions, while the radical reactions proceed readily in aqueous media, although excess amounts of In(0) and alkyl iodides are used.…”

Section: Resultsmentioning

confidence: 93%

“…The results in Table 4 clearly demonstrated the advantage of the above radical methodology over the conventional ionic processes. 1,11,[14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] Although the addition of functionalized nucleophiles to arene-Mn(CO) 3 + complexes gave the corresponding products in reasonable to high yields, stabilized carbanions such as ketone enolates or R-ester carbanions were usually em- ployed. 14,21,[26][27][28][29][30] On the other hand, the nucleophilic addition of the functionalized zinc reagent IZn(CH 2 ) 2 -CO 2 Et or IZn(CH 2 ) 2 CN to complex 1a afforded the R-alkylated product rather than the expected β-alkylated product because of deprotonation of the acidic proton R to the ester or cyano group as reported by Yeh and co-workers.…”

Section: Resultsmentioning

confidence: 99%

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Indium-Mediated Alkyl Radical Addition to (η⁶-Arene)tricarbonylmanganese Complexes in Aqueous Media

2005

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Alkyl radical addition to (η 6 -arene)tricarbonylmangenese complexes was investigated with SmI 2 , zinc, or indium as the radical initiator. Among them, the indium-mediated reactions of (η 6 -arene)tricarbonylmangenese cations with various alkyl iodides in aqueous media afforded the corresponding radical addition-reduction products in moderate to excellent yields.Complexation of an arene ring with a Cr(CO) 3 or Mn-(CO) 3 + moiety significantly reduces the electron density of the arene ring, thus allowing nucleophilic addition to occur. 1 The reduction of the electron density of the phenyl ring also encourages the addition of nucleophilic radicals. 2 For example, Merlic and co-workers demonstrated that ketyl radical addition to Cr(CO) 3 -complexed benzene is at least 100 000 times faster than attack on free benzene. 3 However, only a few examples were reported on radical addition to arene-metal complexes, most of which dealt with ketyl radical addition to (η 6 -arene)Cr(CO) 3 complexes. 3-5 Recently, we reported the first examples of radical addition to (η 6 -arene)tricarbonylmangenese cations (1) by reaction with alkylmercury halides. 5c The alkyl radical added to the phenyl ring in 1 to generate the corresponding 17-valence electron intermediate, which was presumably further reduced by alkylmercury halide, leading to the formation of the stable 18-valence-electron product 2 and to the regeneration of an alkyl radical. 6 In this reaction the alkylmercury halide served not only as the radical precursor but also as the reducing agent. This radical chain process worked well for tert-butylmercury halide, and an excellent yield of the product 2a was achieved. However, with isopropylmercury halide the chain process was less efficient, while almost no reaction could be observed for isobutyl-or n-butyl-mercury halide. Moreover, the high toxicity of alkylmercury halides also limited the application of the above method in organic synthesis. To develop general and convenient methods to conduct the radical reactions, we carried out the following investigation. We report here that alkyl radical addition to (η 6 -arene)Mn(CO) 3 + complexes can be successfully carried out in aqueous media by reaction with indium(0) and alkyl iodides. Results and DiscussionAs discussed above and also in the literature, 2,5c successful radical addition to arene-Mn(CO) 3 + complexes would require both a radical precursor and a reducing agent. A metal reductant and an alkyl halide would be an ideal combination to meet this requirement. Thus, we chose manganese complex 1a as the model substrate and isopropyl iodide as the radical source to explore this possibility (eq 1). The results are presented in Table 1.Treatment of an alkyl iodide with SmI 2 to generate an alkyl radical is well documented. 7 Thus, we first tested the SmI 2 /i-PrI system. The reaction of 1a with .(1) For reviews, see: (a) Kane-Maguire, L. A. P.; Honig, E. P.; Sweigart, D. A.

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Section: Resultssupporting

confidence: 52%

Section: Resultsmentioning

confidence: 93%

Section: Resultsmentioning

confidence: 99%

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Indium-Mediated Alkyl Radical Addition to (η⁶-Arene)tricarbonylmanganese Complexes in Aqueous Media

2005

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“…They include imine, cyano, sulfonyl, nitro, and alkoxycarbonyl [143,144] as well as more esoteric substituents such as diazo [145], phosphine [146], phosphate [147], metal carbene [148], and Cr(CO) 3 [149,150]. Malonate, on the other hand, adds but the resulting carbon-arene bond is too weak and is cleaved under demetallation conditions to regenerate the starting material [151].…”

Section: Addition/oxidation With Arene-mn(co) 3 Cation Complexesmentioning

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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“…Our own contribution in this field has been aimed at studying the reactivity of Fischer-type carbene anions [10] and of deprotonated (alkoxy-substituted arene)tricarbonylchromium complexes [11] towards (η 6 -arene)tricarbonylmanganese complexes. These reactions result in the formation of heterodi-or -polymetallic complexes.…”

Section: Introductionmentioning

confidence: 99%

Reactivity of Metallophosphide Anions with Electrophilic (Arene)tricarbonylmetal Complexes

et al. 2003

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Reaction of metallophosphide anions [(CO)xM′PPh2]− (M′ = Cr, Fe) with neutral tricarbonyl(η6‐fluoroarene)chromium and cationic (η6‐arene)tricarbonylmanganese complexes give rise to the formation of dinuclear complexes. These complexes are obtained either by substitution of the fluoride anion in the (arene)chromium complexes, or by addition to the ring in the (arene)manganese complexes. The X‐ray structure of one homodimetallic (Cr−Cr) complex was obtained and compared with its solution structure. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

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Heteropolymetallic Complex Syntheses by Reiterative Nucleophilic Additions of Lithiated (η⁶-Arene)tricarbonylchromium Compounds to Cationic (η⁶-Benzene)manganese Complexes

Cited by 24 publications

References 47 publications

Indium-Mediated Alkyl Radical Addition to (η⁶-Arene)tricarbonylmanganese Complexes in Aqueous Media

Indium-Mediated Alkyl Radical Addition to (η⁶-Arene)tricarbonylmanganese Complexes in Aqueous Media

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

Reactivity of Metallophosphide Anions with Electrophilic (Arene)tricarbonylmetal Complexes

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Heteropolymetallic Complex Syntheses by Reiterative Nucleophilic Additions of Lithiated (η6-Arene)tricarbonylchromium Compounds to Cationic (η6-Benzene)manganese Complexes

Cited by 24 publications

References 47 publications

Indium-Mediated Alkyl Radical Addition to (η6-Arene)tricarbonylmanganese Complexes in Aqueous Media

Indium-Mediated Alkyl Radical Addition to (η6-Arene)tricarbonylmanganese Complexes in Aqueous Media

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

Reactivity of Metallophosphide Anions with Electrophilic (Arene)tricarbonylmetal Complexes

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Heteropolymetallic Complex Syntheses by Reiterative Nucleophilic Additions of Lithiated (η⁶-Arene)tricarbonylchromium Compounds to Cationic (η⁶-Benzene)manganese Complexes

Indium-Mediated Alkyl Radical Addition to (η⁶-Arene)tricarbonylmanganese Complexes in Aqueous Media

Indium-Mediated Alkyl Radical Addition to (η⁶-Arene)tricarbonylmanganese Complexes in Aqueous Media