Regioselective Oxidation of Phenols to <i>o</i>-Quinones with <i>o</i>-Iodoxybenzoic Acid (IBX)

Magdziak, Derek; Rodriguez, Andy A.; Water, Ryan W. Van De; Pettus, Thomas R. R.

doi:10.1021/ol017068j

Cited by 232 publications

(163 citation statements)

References 23 publications

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“…Both pentavalent and trivalent iodines react with phenols, but oxidized products were different in some cases. [49][50][51][52] For example, reaction of p-methoxyphenol with IBX provided 4-methoxy-1,2-benzoquinone, 53) in contrast to the reaction with PIFA giving p-quinone. 37) Although it remains unclear whether iodine(V) or iodine(III) species was formed during the reaction, 54) a possible catalytic cycle for this oxidation is shown in Chart 2.…”

Section: Resultsmentioning

confidence: 99%

Catalytic Hypervalent Iodine Oxidation Using 4-Iodophenoxyacetic Acid and Oxone: Oxidation of p-Alkoxyphenols to p-Benzoquinones

Yakura

Tian

Yamauchi

et al. 2009

CHEMICAL & PHARMACEUTICAL BULLETIN

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Hypervalent iodine compounds, trivalent iodine compounds such as phenyliodine(III) diacetate (PIDA) and phenyliodine(III) trifluoroacetate (PIFA) and pentavalent iodine reagents such as Dess-Martin periodinane (DMP) and o-iodoxybenzoic acid (IBX), have been used extensively in recent organic synthesis because of their low toxicity, ready availability and easy handling. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] However, these reagents are highly expensive. And stoichiometric amounts of iodine reagents are required to produce equimolar amounts of organic iodine waste. Moreover, pentavalent iodine reagents are potentially explosive. To overcome these disadvantages, catalytic hypervalent iodine oxidations [16][17][18] using mchloroperbenzoic acid (m-CPBA), [19][20][21][22][23][24][25][26][27] Oxone ® (2KHSO 5 · KHSO 4 · K 2 SO 4 ), 28,29) and H 2 O 2 30) as a co-oxidant have been reported recently.Development of efficient methods for synthesis of pquinone and p-quinone derivatives is an important subject in synthetic organic chemistry because they are structural components of numerous natural products and useful synthetic intermediates. [31][32][33][34][35][36] A convenient procedure for p-quinones was hypervalent iodine oxidation of p-alkoxyphenols using PIFA.37) Reactions of p-alkoxyphenols with an equimolar amount of PIFA in a 2 : 1 mixture of acetonitrile and water at room temperature gave the corresponding p-quinones in excellent yield.As part of our study for development of practical and environmentally benign oxidation, we report a mild, efficient and practical procedure for catalytic hypervalent iodine oxidation of p-alkoxyphenols to p-quinones using a catalytic amount of 4-iodophenoxyacetic acid (1a) and Oxone ® as a co-oxidant 38) in 2,2,2-trifluoroethanol-water. Results and DiscussionWe chose Oxone ® as an environmentally safe co-oxidant for a catalytic hypervalent iodine oxidation of p-alkoxyphenols because Oxone ® is an inorganic and water-soluble oxidant with a low order of toxicity, moreover, it is commercially available and inexpensive. 39) Oxone ® has been already used as a co-oxidant under heating conditions in the catalytic IBX oxidation by Vinod 28) and Giannis 29) groups, independently. Because alkoxyphenols have high reactivity under oxidation conditions, we first investigated the oxidative ability of Oxone ® itself. 40) A mixture of 2-pivaloyloxymethyl-4-methoxyphenol (2a) and an equimolar amount of Oxone ® in acetonitrile-water (2 : 1) at room temperature gave the corresponding p-benzoquinone (3a), but the reaction was sluggish and the yield of 3a was only 13% along with 78% of recovered starting 2a after 24 h. Next, we examined reactions of 2a in the presence of several iodoarenes as a catalyst (Chart 1). Table 1 presents the results. According to the procedure reported by Vinod, 28) a mixture of 2a, 0.2 equivalents (eq) of 2-iodobenzoic acid, and 1 eq of Oxone ® in acetonitrile-water was heated at 70°C for 19 h to give a complicated mixture (entry 2). However, a similar reactio...

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Section: Resultsmentioning

confidence: 99%

Catalytic Hypervalent Iodine Oxidation Using 4-Iodophenoxyacetic Acid and Oxone: Oxidation of p-Alkoxyphenols to p-Benzoquinones

Yakura

Tian

Yamauchi

et al. 2009

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…In search of a solution to futher improve the dimerization yield, it appeared that a reagent capable of delivering an oxygen atom after being fixed on the phenolic oxygen would be ideal for ortho-selective oxygenation. The diphenylseleninic anhydride-mediated Barton oxidation 41,42 was an obvious method to try, but a recent report by Pettus and co-workers 43 on the use of IBX for regioselective ortho-oxygenation of phenols brought us to select this λ 5 -iodane reagent.…”

Section: Methodsmentioning

confidence: 99%

Iodane-mediated and electrochemical oxidative transformations of 2-methoxy- and 2-methylphenols

Quideau¹,

Pouységu²,

Deffieux³

et al. 2003

Arkivoc

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A series of 2-methoxy and 2-methylphenols have been submitted to oxygenative oxidation reactions using (1) the λ 3 -iodane DIB, (2) a non-explosive and non-moisture sensitive version of the λ 5 -iodane IBX, named SIBX for Stabilized IBX, and (3) anodic oxidation with the aim of identifying the best reaction conditions for preparing orthoquinonoid cyclohexadienone synthons. Both the use of DIB and anodic oxidation appeared equally valuable for making orthoquinone dimethyl ketals, but the λ 3 -and λ 5-iodane reagents are more appropriate to induce ortho-oxygenation of 2-methylphenols. In particular, SIBX emerged as a useful reagent for mediating ortho-hydroxylation into dimerizing orthoquinols, a tactic that can be applied to the synthesis of natural bis(monoterpenoids) such as aquaticol.

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“…28 The unprotected flavanone 9 (0.03 M dimethyl sulfoxide) is subjected to 2-iodoxybenzoic acid (2.0 equiv) and forms a highly reactive o-quinone intermediate, which is reduced during work-up with sodium sulfite (3.0 equiv) to provide eriodictyol (10) in an isolated 80% yield. As previously observed, phenols bearing electronwithdrawing groups such as −C(O)R, −CHO, and −NO 2 fail to undergo oxidation with 2-iodoxybenzoic acid.…”

Section: Our Synthetic Studiesmentioning

confidence: 99%

(±)-Diinsininone: made nature's way

Selenski

Pettus

2006

Tetrahedron

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We report the synthesis of diinsininone (33), the aglycone of (±)-diinsinin (2). Thereby, we complete the first construction of a proanthocyanidin (PA) type-A compound incorporating a [3.3.1]-bicyclic ketal as its characteristic core. Our strategy utilizes a coupling between a benzopyrilium salt and a flavanone that proves applicable to other PA type-A compounds. During this undertaking, treatment of naringenin (9) with 2-iodoxybenzoic acid (IBX) followed by reductive work-up affords eriodictyol (10). This reactivity mirrors that of catechol hydroxylase (F3H) found in the flavonoid pathway. Other interesting transformations include the formation of flavonoids through an ortho-quinone methide (o-QM) cycloaddition-oxidation sequence and regioselective β-glycosidations of several unprotected flavanones suggesting a likely synthesis of 2 from the aglycone 33.

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Regioselective Oxidation of Phenols to o-Quinones with o-Iodoxybenzoic Acid (IBX)

Cited by 232 publications

References 23 publications

Catalytic Hypervalent Iodine Oxidation Using 4-Iodophenoxyacetic Acid and Oxone: Oxidation of p-Alkoxyphenols to p-Benzoquinones

Catalytic Hypervalent Iodine Oxidation Using 4-Iodophenoxyacetic Acid and Oxone: Oxidation of p-Alkoxyphenols to p-Benzoquinones

Iodane-mediated and electrochemical oxidative transformations of 2-methoxy- and 2-methylphenols

(±)-Diinsininone: made nature's way

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