Efficient Chemoselective Oxidation of Phenylmethanols to Aldehydes with Iodosobenzene

Paraskevopoulou, Patrina; Petalidou, Eleftheria; Psaroudakis, Nikos; Stavropoulos, Pericles; Mertis, Konstantinos

doi:10.1007/s00706-005-0364-1

Cited by 4 publications

(3 citation statements)

References 9 publications

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“…Paraskevopoulou and co-workers found other oxidation conditions (26-Ph 4 PBr-CH 2 Cl 2 ) which were milder than 26-KBr-H 2 O (eqn ( 7)). 40 Under these conditions, primary benzyl alcohols were converted to the corresponding aldehydes in good yields. In contrast, the oxidation of secondary alcohols gave the corresponding ketones in poor yield.…”

Section: ð6þmentioning

confidence: 99%

Hypervalent iodine-mediated oxidation of alcohols

2009

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Over the past two decades there has been a dramatic increse in the use of hypervalent iodine compounds in synthetic organic chemistry due to their mild and selective oxidizing properties. Hypervalent iodine compounds catalyze various oxidation reactions such as the oxidation of alcohols, alpha-oxidation of ketones, oxidative spirocyclization of phenols, etc. Very recently, we found that 2-iodoxybenzensulfonic acid (IBS, ), which was generated from 2-iodobenzenesulfonic acid in situ, is an extremely active and mild catalyst for the highly chemoselective oxidation of various alcohols with powdered Oxone(R) to carbonyl compounds such as aldehydes, carboxylic acids, ketones and cycloalkenones under non-aqueous conditions. In this review, we focus on the design of hypervalent iodine catalysts and review the discovery and development of the oxidation of alcohols with the stoichiometric or catalytic use of hypervalent iodine compounds.

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Section: ð6þmentioning

confidence: 99%

Hypervalent iodine-mediated oxidation of alcohols

2009

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“… , They also showed that secondary alcohols are oxidized to ketones under the same conditions, and other catalytic additives, like iodide and chloride, are less effective . Interestingly, switching the solvent from water to dichloromethane stopped the oxidation of primary aliphatic alcohols using PhIO in the presence of bromide, implying that water has a key mediating role in the reaction . To account for this oxidation, Kita et al proposed the catalytic cycle shown in Figure , in which the iodine(III) species C is responsible for triggering the alcohol oxidation. , The reaction commences with depolymerization of PhIO ( A ) by the metal bromide salt to give B, followed by a ligand exchange to produce C , from which the redox process occurs via deprotonation of the α-carbon by the oxo ligand.…”

Section: Introductionmentioning

confidence: 99%

Computational Investigation into the Mechanistic Features of Bromide-Catalyzed Alcohol Oxidation by PhIO in Water

et al. 2021

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Iodosobenzene (PhIO) is known to be a potent oxidant for alcohols in the presence of catalytic bromide in water. In order to understand this important and practical oxidation process, we have conducted density functional theory studies to shed light on the reaction mechanism. The key finding of this study is that PhIO is not the reactive oxidant itself. Instead, the active oxidant is hypobromite (BrO–), which is generated by the reaction of PhIO with bromide through an SN2-type reaction. Critically, water acts as a cocatalyst in the generation of BrO– through lowering the activation energy of this process. This investigation also demonstrates why BrO– is a more powerful oxidant than PhIO in the oxidation of alcohols. Other halide additives have been reported experimentally to be less effective catalysts than bromideour calculations provide a clear rationale for these observations. We also examined the effect of replacing water with methanol on the ease of the SN2 reaction, finding that the replacement resulted in a higher activation barrier for the generation of BrO–. Overall, this work demonstrates that the hypervalent iodine(III) reagent PhIO can act as a convenient and controlled precursor of the oxidant hypobromite if the right conditions are present.

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“…16 Iodosobenzene was also used in the presence of Ph 4 PBr in CH 2 Cl 2 for the oxidation of benzylic and secondary aliphatic alcohols. 17 Another approach is the use of ion-supported BAIB derivatives in ionic liquid. 18 The BAIB/KBr/chiral Mn(III)Salen system was used in the oxidative kinetic resolution of racemic secondary alcohols.…”

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A Simple Procedure for the Oxidation of Alcohols Using [Bis(acetoxy)iodo]benzene and a Catalytic Amount of Bromide Ions in Ethyl Acetate

Salvo

Campisciano

Beejapur

et al. 2015

Synlett

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OH R 2 R 1 EtOAc, r.t., 24 h O R 2 R 1 primary and secondary benzylic alcohols secondary aliphatic alcohols PhI(OAc) 2 (1.1 equiv) Br -(5 or 20 mol%) TEMPO (1 mol%) OH R 2 R 1 primary aliphatic and secondary allylic alcohols conv. >90% 19 examples CH 2 Cl 2 or EtOAc r.t., 2 h PhI(OAc) 2 (1.1 equiv) KBr (20 mol%) without TEMPO Abstract Primary and secondary benzylic alcohols and secondary aliphatic alcohols were oxidized to the corresponding aldehydes and ketones by using [bis(acetoxy)iodo]benzene (BAIB) and a catalytic amount of bromide ions, from tetrabutylammonium bromide or KBr, in ethyl acetate. The catalytic role of the bromide ions was also highlighted in the oxidation of primary aliphatic alcohols and secondary allylic alcohols carried out in the presence of 1 mol% TEMPO.Oxidation of alcohols is a process that has interested chemists for a very long time. The usefulness of the reaction is well known and a large number of oxidation methods is now available. Several methods are based on the use of a stoichiometric amount of metal-based oxidants such as Collins reagent, pyridinium dichromate or chlorochromate. 1 Methods involving the use of a catalytic amount of metalbased oxidants are also available, such as tetrapropylammonium perruthenate in the presence of an excess of Nmethylmorpholine oxide. 2 Recent demand for green oxidation processes has encouraged the development of cleaner and safer oxidation reactions. The use of soluble metalbased oxidants or catalysts can be avoided by using supported metal catalysts. 3 On the other hand, the use of metal-free catalysts for selective oxidations of organic substrates is very appealing, and several organic oxidants can be used, such as activated dimethyl sulfoxide (DMSO) 4 or catalytic amounts of 2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPO) in the presence of NaOCl. 5 TEMPO can also be used with stoichiometric amounts of inexpensive, safe, and easy to handle oxidants such as [bis(acetoxy)iodo]benzene (BAIB), 6 trichloro isocyanuric acid, 7 Oxone, 8 or iodine. 9 Among them, hypervalent iodine compounds such as BAIB have been used successfully. 10 Pentavalent iodine reagents such as Dess-Martin periodinane 11 and o-iodoxybenzoic acid 12 are mild and efficient oxidizing agents that allow carbonyl compounds to be obtained from alcohols with high yields in organic solvents such as CH 2 Cl 2 , DMSO, and acetone. However, iodine(V) reagents cannot be stored for a long time. In place of iodine(V) reagents, readily available and relatively stable iodine(III) reagents can be used. The group of Kita has described several examples of oxidation of alcohols by using iodine(III) reagents. They reported the use of iodosobenzene (PhIO) with KBr, in water under neutral conditions 13 as well as the use of polymer-supported (diacetoxyiodo)benzene (PSDIB). 14 Under these conditions, acids, ketones, and lactones were obtained. Instead of KBr, the same authors employed Et 4 N + Br -in water. Under the latter conditions, several secondary alcohols were easily converted into the correspo...

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Efficient Chemoselective Oxidation of Phenylmethanols to Aldehydes with Iodosobenzene

Cited by 4 publications

References 9 publications

Hypervalent iodine-mediated oxidation of alcohols

Hypervalent iodine-mediated oxidation of alcohols

Computational Investigation into the Mechanistic Features of Bromide-Catalyzed Alcohol Oxidation by PhIO in Water

A Simple Procedure for the Oxidation of Alcohols Using [Bis(acetoxy)iodo]benzene and a Catalytic Amount of Bromide Ions in Ethyl Acetate

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