Ligand- and base-free synthesis of phenols by rapid oxidation of arylboronic acids using iron(III) oxide

Sawant, Sanghapal D.; Hudwekar, Abhinandan D.; Kumar, K. Raghavendra; Venkateswarlu, Vunnam; Singh, Parvinder Pal; Vishwakarma, Ram A.

doi:10.1016/j.tetlet.2013.12.003

Cited by 49 publications

(24 citation statements)

References 35 publications

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“…The readily available phenylboronic acid [8] is stable to heat, air, and moisture, making it an attractive and valuable precursor of phenol by its oxidation with CuSO 4 [9][10]. Thus, stirring phenylboronic acid in a solvent, followed by addition of CuSO 4 produces Cu(I).…”

Section: Introductionmentioning

confidence: 99%

Phenylboronic Acid/CuSO4 as an Efficient Catalyst for the Synthesis of 1,4-Disubstituted-1,2,3-Triazoles from Terminal Acetylenes and Alkyl Azides

et al. 2017

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<p>The synthesis of 1,4-disubstituted-1,2,3-triazoles from alkyl azides and terminal alkynes at room temperature and under microwave heating was attained using Cu(I), generated <em>in-situ </em>from copper(II) sulfate and phenylboronic acid, as catalyst. Twelve new triazoles were obtained in moderate to good yields (53-98%), and the products were obtained by crystallization from the mixture reaction without further purification.</p>

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Section: Introductionmentioning

confidence: 99%

Phenylboronic Acid/CuSO4 as an Efficient Catalyst for the Synthesis of 1,4-Disubstituted-1,2,3-Triazoles from Terminal Acetylenes and Alkyl Azides

et al. 2017

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“…Photoredox oxidative hydroxylation of boronic acids has attracted much attention in the past decade. Transition metal catalysts [28][29][30][31] and metal free catalysts [32][33][34][35][36][37] showed nice catalytic activities in such transformations. Mechanistic studies showed that superoxide radical anion was generated by single electron transfer from highly reductive photocatalyst to oxygen.…”

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confidence: 99%

“…After hydrolysis, phenol or alcohol would be formed as the final product (Scheme 1b). [28][29][30][31][32][33][34][35][36][37] With our continues research interest in aerobic photo oxidation reactions, [38][39][40][41] we turned our interest to study thioxanthone as catalyst for this transformation. Thioxanthone was normally used as photo initiator in polymer chemistry.…”

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confidence: 99%

“…This result indicated the oxygen atom in the product was completely from oxygen in the air (Scheme 3c). With the information above and literature precedence, [28][29][30][31][32][33][34][35][36][37] a possible mechanism was proposed in Scheme 4. Upon photo irradiation, the excited 1f donate an electron to oxygen gave superoxide radical anion.…”

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confidence: 99%

“…35 Further rearrangement of 13 and hydrolysis of 14 furnished the final product 3. 30,33,52 In conclusion, we developed a photochemically aerobic oxidative hydroxylation of boronic acids. This method employed 7H-benzo[c]thioxanthen-7-one as the metal-free catalyst and DMC as the green solvent.…”

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confidence: 99%

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Visible light induced oxidative hydroxylation of boronic acids

Ding

Zhang

Chen

et al. 2019

Tetrahedron Letters

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Oxidative hydroxylation of boronic acids into phenols or alcohols is a hot topic in organic synthesis. 1-6 Strong oxidants, such as high-valence halogen compounds, 7-10 peroxide, 11-14 ozone, 15 and N-oxide, 16 are efficient reagents in such transformations. However, these methods are not environmentally friendly, since lots of wastes are formed. Oxygen in air is considered as green and abundant oxidant. Methods employing oxygen have been well studied. Some Ru, 17,18 Pd, 19 Fe, 20 Cu 21-24 complexes or Cu, 25 Fe, 26 Au 27 nanoparticles were proved to be effective catalysts in this field. However, the synthesis of catalysts is complicated and transitional metals were harmful to the environment (Scheme 1a).

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C₇₀ Fullerene‐Catalyzed Metal‐Free Photocatalytic ipso‐Hydroxylation of Aryl Boronic Acids: Synthesis of Phenols

et al. 2018

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A metal-free C 70 fullerene-catalyzed method has been developed for the ipso-hydroxylation of aryl and heteroaryl boronic acids to corresponding phenols under photocatalytic conditions. The reaction proceeds under oxygen atmosphere and the mechanistic study revealed that C 70 plays a critical role in the generation of reactive oxygen species in the presence of blue light. Reactions in the presence of 18 O-labelled water and oxygen confirmed the generation of reactive oxygen species from oxygen molecule. Amine used as a reductant could be recovered in the form of imine. The current method is also applicable to the synthesis of aryl ethers in one-pot two-step process.

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Ligand- and base-free synthesis of phenols by rapid oxidation of arylboronic acids using iron(III) oxide

Cited by 49 publications

References 35 publications

Phenylboronic Acid/CuSO4 as an Efficient Catalyst for the Synthesis of 1,4-Disubstituted-1,2,3-Triazoles from Terminal Acetylenes and Alkyl Azides

Phenylboronic Acid/CuSO4 as an Efficient Catalyst for the Synthesis of 1,4-Disubstituted-1,2,3-Triazoles from Terminal Acetylenes and Alkyl Azides

Visible light induced oxidative hydroxylation of boronic acids

C₇₀ Fullerene‐Catalyzed Metal‐Free Photocatalytic ipso‐Hydroxylation of Aryl Boronic Acids: Synthesis of Phenols

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Ligand- and base-free synthesis of phenols by rapid oxidation of arylboronic acids using iron(III) oxide

Cited by 49 publications

References 35 publications

Phenylboronic Acid/CuSO4 as an Efficient Catalyst for the Synthesis of 1,4-Disubstituted-1,2,3-Triazoles from Terminal Acetylenes and Alkyl Azides

Phenylboronic Acid/CuSO4 as an Efficient Catalyst for the Synthesis of 1,4-Disubstituted-1,2,3-Triazoles from Terminal Acetylenes and Alkyl Azides

Visible light induced oxidative hydroxylation of boronic acids

C70 Fullerene‐Catalyzed Metal‐Free Photocatalytic ipso‐Hydroxylation of Aryl Boronic Acids: Synthesis of Phenols

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C₇₀ Fullerene‐Catalyzed Metal‐Free Photocatalytic ipso‐Hydroxylation of Aryl Boronic Acids: Synthesis of Phenols