Oxygen insertion into palladium-arene bonds by iodosylbenzene

Bhawmick, Rupa; Biswas, Hiranmay; Bandyopadhyay, Pinaki

doi:10.1016/0022-328x(95)05476-6

Cited by 30 publications

(19 citation statements)

References 19 publications

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“…16)). 24,25 Similarly, amination of C-H bonds was also reported by Sanford using PhIQNTs as the oxidant (eqn ( 17)). 26 ð16Þ ð17Þ 2.1.3.3 Oxidation with [ArIAr]X. Canty and co-workers reported the first example to oxidize Pd(II) complex 12 to Pd(IV) species by diphenyliodine(III) triflate.…”

Section: ð13þmentioning

confidence: 61%

Organopalladium(iv) chemistry

et al. 2010

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Although the chemistry of Pd(0), Pd(I) and Pd(II) is well established, high oxidation state Pd(IV) complexes are less well-known. This situation has highly changed in recent years. Many well-defined Pd(IV) complexes has been isolated and characterized, providing evidence for a series of proposed Pd(II)/Pd(IV) catalytic reactions. A deep understanding of the behavior of Pd(IV) complexes could lead to the design and development of novel reactions that could not be accessed by traditional Pd(0)/Pd(II) chemistry. This critical review describes the stoichiometric reactions of Pd(IV) complexes and discusses their potential mechanism in catalytic reactions (137 references).

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Section: ð13þmentioning

confidence: 61%

Organopalladium(iv) chemistry

et al. 2010

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“…Oxygen atom insertion into Pd−C bonds of a series of cyclopalladated azo compounds by peracids and iodosylbenzene has been achieved successfully. − Oxidative cleavage of M−C bonds (M = Pd, Pt) and stereoselective product formation from the reaction of M−C-bonded compounds with peracids are remarkable. − Oxygenation of cyclopalladated N , N -dimethylbenzylamine compounds by inorganic and organic peroxides has also been thoroughly investigated. , Preliminary kinetic studies on the oxidation of type 1 compounds by MCPBA have revealed the possible existence of the intermediate compound [I] prior to the formation of the Pd−C bond oxidized product 2 . In similar oxygenation of cyclopalladated N , N -dimethylbenzylamine compounds by inorganic and organic peroxides, nucleophilic end-on attack of the metal center on the O−O bond of the oxidant to give transient Pd(IV) has been proposed .…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Palladium−Carbon Bond Oxidation: Dramatic Solvent Effect

Kamaraj

Bandyopadhyay

1999

Organometallics

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Pentafluoroiodosylbenzene (C6F5IO) selectively oxidizes Pd−C bonds of a series of cyclopalladated 2-(alkylthio)azobenzene complexes. The kinetics of oxygen atom insertion into the Pd−C bond of one representative compound has been studied in detail to understand the mechanism of this reaction. At 20 °C Pd−C bond oxidation takes place smoothly in acetonitrile at a rate of 0.08 M-1 s-1, whereas this reaction does not proceed in solvents such as dichloromethane and chloroform. The ΔH ⧧ and ΔS ⧧ values for this reaction are 55.5 ± 3.5 kJ/mol and −75.7 ± 11.5 eu, respectively. Among other oxidants, hydroperoxy radical (for example, t-BuOO•) is found to be extremely efficient, whereas the highly electrophilic oxoiron(IV) porphyrin cation radical (oxene) is incapable of oxidizing the Pd−C bond. Oxene, however, selectively oxidizes the thioether functionality. These observations suggest that nucleophilic attack of the oxidant molecule on palladium(II) could be the most crucial step prior to Pd−C bond oxidation. A large negative value of ΔS ⧧ supports an associative mechanism, and a smooth reaction in polar solvent supports a polar intermediate structure. Hydroperoxides, in the presence of a catalytic amount of iron(III) porphyrin chloride, selectively oxidizes the Pd−C bond. This observation, coupled with the fact that oxene oxidizes the thioether functionality, indicates that oxene may not be the major reactive intermediate in hydroperoxide oxidations. On the basis of these experimental results, we have attempted to draw a plausible mechanism of Pd−C bond oxidation.

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“…Complexes of type 2 were previously described in reactions of dimeric dichloro-bridged CPCs with various oxidants including m-CPBA; they are one of the two types of oxygen-insertion products reported in these studies [38,47,49,50,54]. It appears that type 2 complexes are relatively unstable, especially during chromatographic purification, and gradually produce the corresponding compounds of type 4 as well as, presumably, PdCl 2 .…”

Section: Resultsmentioning

confidence: 92%

“…It appears that type 2 complexes are relatively unstable, especially during chromatographic purification, and gradually produce the corresponding compounds of type 4 as well as, presumably, PdCl 2 . A tendency for decomposition was also noted for one of the azobenzene-derived complexes of this type, and likewise, it was proposed that the corresponding bis(j 2 -N,O)Pd complexes of type 4 were produced along with PdCl 2 [54].…”

Section: Resultsmentioning

confidence: 95%

“…Oxygen insertion into the C-Pd bond of cyclopalladated complexes can be accomplished by any of the following reagents: m-chloroperoxybenzoic acid (m-CPBA) (used alone [34][35][36][37][38][39][40][41][42][43][44][45][46] or with an iron(III) porphyrin catalyst [37]), other peroxy acids [40], t-BuOOH (used alone [47][48][49][50] or with a catalyst [34,35,[47][48][49][50][51][52]), hydrogen peroxide in the presence of an iron(III) porphyrin catalyst [53], pentafluoroiodosylbenzene C 6 F 5 IO (alone [37,52], in a combination with t-BuOOH [37,52] or in the presence of an iron(III) porphyrin catalyst [37,52]), iodosylbenzene C 6 H 5 IO [54], [di(benzoyloxy)iodo]benzene PhI(O 2 CPh) 2 [55] and the molybdenum peroxide MoO(O 2 ) 2 ÁHMPAÁH 2 O (HMPA = hexamethylphosphoric triamide) [14,56]. The mechanisms involved in these transformations appear to be different [5]; however, in all cases, the C-Pd bond is transformed into the C-O-Pd moiety.…”

Section: Introductionmentioning

confidence: 99%

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