Hydroxylation of polycyclic alkanes with molecular oxygen catalyzed by N-hydroxyphthalimide (NHPI) combined with transition metal salts

Ishii, Yasutaka; Kato, Susumu; Iwahama, Takahiro; Sakaguchi, Satoshi

doi:10.1016/0040-4039(96)00992-6

Cited by 78 publications

(33 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[29] For example, the selective autoxidation of adamantane to adamantanediol [28] and/or -triol [Equation (3)] in the presence of a catalyst Table 1. O À H bond dissociation energies ( BDE ) in N-substituted hydroxylamines.…”

Section: ð2þmentioning

confidence: 99%

“…Ishii and coworkers subsequently showed [26,27] that the combination of NHPI with a variable valence metal (what has become known as the Ishii system), notably cobalt, affords an effective catalytic system for the autoxidation of a broad range organic substrates, e.g., alkanes [28] and alkylaromatics. [29] For example, the selective autoxidation of adamantane to adamantanediol [28] and/or -triol [Equation (3)] in the presence of a catalyst Table 1.…”

Section: ð2þmentioning

confidence: 99%

See 1 more Smart Citation

Organocatalytic Oxidations Mediated by Nitroxyl Radicals

2004

View full text Add to dashboard Cite

The use of nitroxyl radicals, alone or in combination with transition metals, as catalysts in oxidation processes is reviewed from both a synthetic and a mechanistic viewpoint. Two extremes of reactivity can be distinguished: stable (persistent) dialkylnitroxyls, such as the archetypal TEMPO, and reactive diacylnitroxyls, derived from N-hydroxy imides, such as N-hydroxyphthalimide (NHPI). The different types of reactivity observed are rationalized by considering the bond dissociation energies (BDEs) of the respective N-hydroxy precursors, substrates and reaction intermediates. Reactive diacylnitroxyl radicals are generated in situ from the corresponding N-hydroxy compound. The protagonist, NHPI, catalyzes a wide variety of free radical autoxidations, improving both activities and selectivities by increasing the rate of chain propagation and/or decreasing the rate of chain termination. In the absence of metal co-catalysts improved conversions and selectivities are obtained in the autoxidation of hydrocarbons to the corresponding alkyl hydroperoxides. For example, cyclohexylbenzene afforded the 1-hydroperoxide in 97.6% selectivity at 32% conversion when the autoxidation was performed in the presence of 0.5 mol % NHPI, and the product hydroperoxide as initiator, at 100 8C. This forms the basis for a potential coproduct-free route from benzene to phenol. In combination with transition metal co-catalysts, notably cobalt, NHPI and related compounds, such as N-hydroxysaccharin NHS, afford effective catalytic systems for the effective autoxidation of hydrocarbons, e.g., toluenes to carboxylic acids, under mild conditions. In the case of the less reactive cycloalkanes, NHS proved to be a more active catalyst than NHPI which is attributed to the higher reactivity of the intermediate nitroxyl radical, resulting from the replacement of a carbonyl group in NHPI by the more strongly electron-attracting sulfonyl group. Stable dialkylnitroxyl radicals, exemplified by TEMPO, catalyze oxidations of, e.g., alcohols, with single oxygen donors such as hypochlorite and organic peracids. The reactions involve the intermediate formation of the corresponding oxoammonium cation as the active oxidant. Alternatively, in conjunction with transition metals, notably ruthenium and copper, they catalyze aerobic oxidations of alcohols. These reactions involve metal-centered dehydrogenations and the role of the TEMPO is to facilitate regeneration of the catalyst (Ru and Cu) and oxidation of the alcohol (Cu) via hydrogen abstraction or one-electron oxidation processes. Detailed mechanistic investigations, including kinetic isotope effects, revealed that oxoammonium cations are not involved as intermediates in these reactions. In contrast, oxoammonium cations are involved in the aerobic oxidation of alcohols catalyzed by the copper-dependent oxidase, laccase, in combination with TEMPO. This different mechanistic pathway is attributed to the much higher redox potential of the copper(II) in the enzyme. Similarly, N-hydroxy compounds such as ...

show abstract

Section: ð2þmentioning

confidence: 99%

Section: ð2þmentioning

confidence: 99%

Organocatalytic Oxidations Mediated by Nitroxyl Radicals

2004

View full text Add to dashboard Cite

show abstract

“…[5a,5d,33] It was found that the NHPI-catalyzed aerobic oxidation of adamantane is considerably accelerated by adding a small amount of a Co salt. [13,34,35] Thus, the oxidation of adamantane (3) in the presence of NHPI (10 mol %) and Co(acac) 2 (0.5 mol %) in acetic acid under dioxygen (1 atm) for 6 h produced 1-adamantanol (4) (43%), 1,3-adamantanediol (6) (40%), and 2-adamantanone (5) (8%) ( Table 4). Interestingly, VO(acac) 2 and MoO 2 (acac) 2 , which are rarely employed in aerobic oxidation, were also good additives, while the effect of manganese salts was moderate compared with that of Co salts.…”

Section: Effect Of Transition Metal Salts On Nhpicatalyzed Oxidation mentioning

confidence: 99%

“…2-Octene was allowed to react under O 2 (1 atm) in the presence of 1-phenylethanol under the influence of catalytic amounts of NHPI (10 mol %) and HFA (10 mol %) in benzonitrile at 80°C for 24 h, giving 2,3-epoxyoctane in 73% yield based on 90% conversion (Equation 34). [125] The present example is the first epoxidation with H 2 O 2 generated in situ from alcohols and O 2 without any metal catalysts.…”

Section: Epoxidation Of Alkenes Using Hydrocarbons As Hydroperoxide Smentioning

confidence: 99%

Innovation of Hydrocarbon Oxidation with Molecular Oxygen and Related Reactions

2001

Self Cite

View full text Add to dashboard Cite

An innovation of the aerobic oxidation of hydrocarbons through catalytic carbon radical generation under mild conditions was achieved by using N‐hydroxyphthalimide (NHPI) as a key compound. Alkanes were successfully oxidized with O2 or air to valuable oxygen‐containing compounds such as alcohols, ketones, and dicarboxylic acids by the combined catalytic system of NHPI and a transition metal such as Co or Mn. The NHPI‐catalyzed oxidation of alkylbenzenes with dioxygen could be performed even under normal temperature and pressure of dioxygen. Xylenes and methylpyridines were also converted into phthalic acids and pyridinecarboxylic acids, respectively, in good yields. The present oxidation method was extended to the selective transformations of alcohols to carbonyl compounds and of alkynes to ynones. The epoxidation of alkenes using hydroperoxides or H2O2 generated in situ from hydrocarbons or alcohols and O 2 under the influence of the NHPI was demonstrated and seems to be a useful strategy for industrial applications. The NHPI method is applicable to a wide variety of organic syntheses via carbon radical intermediates. The catalytic carboxylation of alkanes was accomplished by the use of CO and O2 in the presence of NHPI. In addition, the reactions of alkanes with NO2 and SO2 catalyzed by NHPI provided efficient methods for the synthesis of nitroalkanes and sulfonic acids, respectively. A catalytic carbon‐carbon bond forming reaction was achieved by allowing carbon radicals generated in situ from alkanes or alcohols to react with alkenes under mild conditions. 1 Introduction 2 Discovery of NHPI as Carbon Radical Producing Catalyst from Alkanes 2.1 Historical Background 2.2 Catalysis of NHPI in Aerobic Oxidation 3 NHPI‐Catalyzed Aerobic Oxidation 3.1 Oxidation of Benzylic Compounds 3.2 Alkane Oxidations with Molecular Oxygen 3.3 Oxidation of Alkylbenzenes 3.4 Practical Oxidation of Methylpyridines 3.5 Preparation of Acetylenic Ketones via Alkyne Oxidation 3.6 Oxidation of Alcohols 3.7 Selective Oxidation of Sulfides to Sulfoxides 3.8 Production of Hydrogen Peroxide by Aerobic Oxidation of Alcohols 3.9 Epoxidation of Alkenes using Molecular Oxygen as Terminal Oxidant 4 Carboxylation of Alkanes with CO and O2 5 Utilization of NOx in Organic Synthesis 5.1 First Catalytic Nitration of Alkanes using NO2 5.2 Reaction of NO with Organic Compounds 6 Sulfoxidation of Alkanes Catalyzed by Vanadium 7 Carbon‐Carbon Bond Forming Reaction via Catalytic Carbon Radicals Generated from Various Organic Compounds Assisted by NHPI 7.1 Oxyalkylation of Alkenes with Alkanes and Dioxygen 7.2 Synthesis of α‐Hydroxy‐γ‐lactones by Addition of α‐Hydroxy Carbon Radicals to Unsaturated Esters 7.3 Hydroxyacylation of Alkenes using 1,3‐Dioxolanes and Dioxygen 8 Conclusions

show abstract

“…proposed N -hydroxyphthalimide (NHPI, Scheme 1), with or without transition metal ions, as a homogeneous organocatalyst for the liquid-phase oxidation of several substrates [12][13][14][15][16][17][18][19][20][21][22][23]. At present, many accounts can be found on the use of various N -hydroxyimides as efficient catalysts for various oxyfunctionalizations [24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%