Selectivity versus Reactivity - Recent Advances in RuO<sub>4</sub>-Catalyzed Oxidations

Plietker, Bernd

doi:10.1055/s-2005-872172

Cited by 116 publications

(84 citation statements)

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“…Previous findings related to the RICO mechanism for PAH oxidation suggested that C−C bond scission is involved in the first step of the reaction. Plietker suggested that the mechanism may be similar to the oxidative cleavage of double bonds, in which RuO 4 adds to a double bond to form a ruthenium(VI) compound . Frenking and co‐workers have used DFT calculations to show that RuO 4 will form stable ruthenium(VI) adducts with ethene through a [3+2] cycloaddition of RuO 4 across the double bond .…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Insights into Selective Oxidation of Polyaromatic Compounds using RICO Chemistry

Nowicka

Hickey

Sankar

et al. 2018

Chemistry A European J

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Ruthenium-ion-catalyzed oxidation (RICO) of polyaromatic hydrocarbons (PAHs) has been studied in detail using experimental and computational approaches to explore the reaction mechanism. DFT calculations show that regioselectivity in these reactions can be understood in terms of the preservation of aromaticity in the initial formation of a [3+2] metallocycle intermediate at the most-isolated double bond. We identify two competing pathways: C-C bond cleavage leading to a dialdehyde and C-H activation followed by H migration to the RuO complex to give diketones. Experimentally, the oxidation of pyrene and phenanthrene has been carried out in monophasic and biphasic solvent systems. Our results show that diketones are the major product for both phenanthrene and pyrene substrates. These diketone products are shown to be stable under our reaction conditions so that higher oxidation products (acids and their derivatives) are assigned to the competing pathway through the dialdehyde. Experiments using O-labelled water do show incorporation of oxygen from the solvents into products, but this may take place during the formation of the reactive RuO species rather than directly during PAH oxidation. When the oxidation of pyrene is carried out using D O, a kinetic isotope effect (KIE) is observed implying that water is involved in the rate-determining step leading to the diketone products.

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Section: Introductionmentioning

confidence: 99%

Mechanistic Insights into Selective Oxidation of Polyaromatic Compounds using RICO Chemistry

Nowicka

Hickey

Sankar

et al. 2018

Chemistry A European J

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“…The furan ring can be oxidized to the corresponding carboxylic acid by the action of ozone or ruthenium tetroxide, the latter being generated from hydrated ruthenium (III) chloride or ruthenium (IV) oxide [21] Ruthenium tetroxide is formed in situ from RuCl 3 or RuO 2 by using an appropriate oxidant such as NaIO 4 , KIO 4 , NaClO, NaBrO 3 , Ce(SO 4 ) 2 , K 2 S 2 O 8 , Oxone ® or H 5 IO 6 [22] thus allowing the use of the precursor ruthenium derivative in a catalytic amount (Scheme 3) [23]. The reaction takes place in the interfacial area of a biphasic system carbon tetrachloride:water.…”

Section: Furan As C-1 Synthonmentioning

confidence: 99%

Furan Oxidations in Organic Synthesis: Recent Advances and Applications

Merino¹,

Tejero²,

Delso³

et al. 2007

COC

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“…1) Ruthenium tetroxide (RuO 4 ) is well known as a highly effective oxidant, [2][3][4] and the oxidative cleavage of simple CϭC bonds is one of the most common reactions between RuO 4…”

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confidence: 99%

“…This chemistry has been extensively studied. 1) Ruthenium tetroxide (RuO 4 ) is well known as a highly effective oxidant, [2][3][4] and the oxidative cleavage of simple CϭC bonds is one of the most common reactions between RuO 4 2) and alkenes. However, only a low effort regarding the oxidative cleavage of the CϭC double bond to the corresponding carbonyl compounds in enol ethers, enol esters and enamines has been made to date.…”

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confidence: 99%

An Efficient Transformation of Cyclic Ene-carbamates into .OMEGA.-(N-Formylamino)carboxylic Acids by Ruthenium Tetroxide Oxidation

Kaname

Yoshifuji

Sashida

2008

CHEMICAL & PHARMACEUTICAL BULLETIN

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The high-valent metal-promoted oxidation of a carboncarbon double (CϭC) bond with cleavage is a promising synthetic route to the corresponding carbonyl compounds. This chemistry has been extensively studied.1) Ruthenium tetroxide (RuO 4 ) is well known as a highly effective oxidant, [2][3][4] and the oxidative cleavage of simple CϭC bonds is one of the most common reactions between RuO 42) and alkenes. However, only a low effort regarding the oxidative cleavage of the CϭC double bond to the corresponding carbonyl compounds in enol ethers, enol esters and enamines has been made to date. To the best of our knowledge, there are only two papers. The first example of this type of reaction was described by Desai and co-workers, 5) who reported one case that attempted the cleavage of a CϭC bond in steroidal enamines. Torii and co-workers 6) revealed the procedure for the RuO 4 oxidative cleavage of enolic olefins including two six-membered nitrogen-containing heterocyles that afforded the carbonyl compounds under the conditions using the substrate in a suspension of CCl 4 and H 2 O in the presence of RuO 2 · xH 2 O and NaIO 4 .On the other hand, we have been working on the transformation of cyclic [7][8][9] and acyclic [10][11][12] N-acyl amines into the corresponding lactams and imides including the natural products [13][14][15][16][17] by the RuO 4 oxidation. The double layer oxidation method using a catalytic amount of RuO 2 hydrate, an excess of a NaIO 4 aqueous solution and ethyl acetate system was established for these purposes in our laboratory. In addition, it was recently reported that the single layer RuO 4 oxidation 18) of cyclic N-acyl amines using a tert-butanol and NaIO 4 aqueous solution system gave the ring opened wamino acids (Chart 1). We now report that the simple RuO 4 oxidation of various cyclic ene-carbamates including the optically active one into the corresponding w-(N-formylamino)carboxylic acids and the formal synthesis of L-carnitine as the utilization of this RuO 4 oxidation. Results and DiscussionThe substrates, five-, six-and seven-membered cyclic enecarbamates (1a, 2a, 3a), were prepared from the corresponding N-acyl amines via the N-acyl lactams in good yields by the reported method. 19) We have previously tested the utility of the urethane type N-protecting groups, 9) benzyloxycarbonyl (Z), p-nitrobenzyloxycarbonyl (PNZ), trichloroethoxycarbonyl (Troc) and tert-butoxycarbonyl (Boc) groups for the RuO 4 oxidation of the cyclic amines, and found the following three points: (1) the Z group is decomposed by RuO 4 that produced a low yield of products, (2) the PNZ and Troc groups generally require a longer reaction until the starting materials disappear, and (3) the Boc group is stable, accelerates the oxidation, and affords the products in high yields. In addition, the Boc group can be easily removed from the Nprotected amines by common procedures. Thus, we selected the Boc group as the N-protecting group for this RuO 4 oxidation.RuO 4 Oxidation of Ene-carbamates The oxidation of N-tert-but...

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Selectivity versus Reactivity - Recent Advances in RuO₄-Catalyzed Oxidations

Cited by 116 publications

References 52 publications

Mechanistic Insights into Selective Oxidation of Polyaromatic Compounds using RICO Chemistry

Mechanistic Insights into Selective Oxidation of Polyaromatic Compounds using RICO Chemistry

Furan Oxidations in Organic Synthesis: Recent Advances and Applications

An Efficient Transformation of Cyclic Ene-carbamates into .OMEGA.-(N-Formylamino)carboxylic Acids by Ruthenium Tetroxide Oxidation

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Selectivity versus Reactivity - Recent Advances in RuO4-Catalyzed Oxidations

Cited by 116 publications

References 52 publications

Mechanistic Insights into Selective Oxidation of Polyaromatic Compounds using RICO Chemistry

Mechanistic Insights into Selective Oxidation of Polyaromatic Compounds using RICO Chemistry

Furan Oxidations in Organic Synthesis: Recent Advances and Applications

An Efficient Transformation of Cyclic Ene-carbamates into .OMEGA.-(N-Formylamino)carboxylic Acids by Ruthenium Tetroxide Oxidation

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Selectivity versus Reactivity - Recent Advances in RuO₄-Catalyzed Oxidations