Transition-Metal-Free Borylation of Aryl Bromide Using a Simple Diboron Source

Lim, T. K.; Ryoo, Jeong Yup; Han, Min Su

doi:10.1021/acs.joc.0c01065

Cited by 10 publications

(7 citation statements)

References 56 publications

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“…(M, see SI for detail). Additionally, control experiment performed using B 2 pin 2 and base without the presence of B BiPy did not lead to the borylated product (N, see SI for detail) [37] …”

Section: Resultsmentioning

confidence: 94%

“…Additionally, control experiment performed using B 2 pin 2 and base without the presence of B BiPy did not lead to the borylated product (N, see SI for detail). [37] The organocatalytic reaction for the formation of biaryls through arene CÀ H arylation has been accepted to involve a single electron transfer (SET) process, generating a highly reactive aryl radical species. The generation of a radical initiator from the combination of organic ligand and base have been proposed, which subsequently injects an electron to the aryl substrate.…”

Section: Bipymentioning

confidence: 99%

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Role of N, N′‐Diboryl‐4, 4′‐bipyridinylidene in the Transition‐Metal‐Free Borylation of Aryl Halides and Direct C−H Arylation of Unactivated Benzene

et al. 2022

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Dedicated to Prof. Dr. Rainer Streubel on his 64 th birthday N,N'-Diboryl-4,4'-bipyridinylidene ( B BiPy) has been utilized in sub-stoichiometric amounts along with anionic base as one electron donor species for both transition metal-free borylation of aryl halides and arene CÀ H functionalization with aryl iodides for biaryl syntheses. Reaction between B BiPy and potassium tertbutoxide or methoxide has led to the formation of 4,4'bipyridine radical anion (BiPy •À ) with the release of an electron. The BiPy •À has been structurally characterized. The single electron released is transferred to aryl halides generating aryl radicals, which then react with diboron in the presence of methoxide to form aryl boronate and with unactivated benzene in the presence of tert-butoxide to form biaryls. Substrate scopes studies showed that aryl iodides and bromides undergo borylation (1B-12B), while only aryl iodides undergo CÀ C bond formation with arene CÀ H (1C-8C) through radical chain reaction. Mechanisms for CÀ B and CÀ C bond formation have been proposed based on the experimental findings.

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Section: Resultsmentioning

confidence: 94%

Section: Bipymentioning

confidence: 99%

Role of N, N′‐Diboryl‐4, 4′‐bipyridinylidene in the Transition‐Metal‐Free Borylation of Aryl Halides and Direct C−H Arylation of Unactivated Benzene

et al. 2022

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“…Reported in 2009, Marder and co-workers utilized the solvent in a one-pot C–H borylation/Suzuki-Miyaura cross-coupling sequence, a transformation shown to be highly effective for both aryl and heteroaryl substrates . Borylation in protic solvents such as MeOH and EtOH has also been reported including in the 2020 report on transition metal-free borylation of aryl halides using bis-boronic acid in MeOH …”

Section: Common Reactions In Dipolar Aprotic or Ethereal Solvents Rep...mentioning

confidence: 96%

“…174 Borylation in protic solvents such as MeOH 303 and EtOH 304 has also been reported including in the 2020 report on transition metal-free borylation of aryl halides using bis-boronic acid in MeOH. 305 …”

Section: Common Reactions In Dipolar Aprotic or Ethereal Solvents Rep...mentioning

confidence: 99%

Replacement of Less-Preferred Dipolar Aprotic and Ethereal Solvents in Synthetic Organic Chemistry with More Sustainable Alternatives

et al. 2022

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Dipolar aprotic and ethereal solvents comprise just over 40% of all organic solvents utilized in synthetic organic, medicinal, and process chemistry. Unfortunately, many of the common “go-to” solvents are considered to be “less-preferable” for a number of environmental, health, and safety (EHS) reasons such as toxicity, mutagenicity, carcinogenicity, or for practical handling reasons such as flammability and volatility. Recent legislative changes have initiated the implementation of restrictions on the use of many of the commonly employed dipolar aprotic solvents such as dimethylformamide (DMF) and N -methyl-2-pyrrolidinone (NMP), and for ethers such as 1,4-dioxane. Thus, with growing legislative, EHS, and societal pressures, the need to identify and implement the use of alternative solvents that are greener, safer, and more sustainable has never been greater. Within this review, the ubiquitous nature of dipolar aprotic and ethereal solvents is discussed with respect to the physicochemical properties that have made them so appealing to synthetic chemists. An overview of the current legislative restrictions being imposed on the use of dipolar aprotic and ethereal solvents is discussed. A variety of alternative, safer, and more sustainable solvents that have garnered attention over the past decade are then examined, and case studies and examples where less-preferable solvents have been successfully replaced with a safer and more sustainable alternative are highlighted. Finally, a general overview and guidance for solvent selection and replacement are included in the Supporting Information of this review.

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“…Overall, none of the previously mentioned diboron-based reduction methods show chemoselectivity for nitro groups over vinyl groups. Previously, our group demonstrated the borylation of aryl bromides using B 2 (OH) 4 . During the study, we found that B 2 (OH) 4 showed reducing capabilities in the presence of KO t Bu without a transition-metal catalyst at mild temperatures.…”

Section: Introductionmentioning

confidence: 96%

Metal-Free, Rapid, and Highly Chemoselective Reduction of Aromatic Nitro Compounds at Room Temperature

et al. 2022

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In this study, we developed a metal-free and highly chemoselective method for the reduction of aromatic nitro compounds. This reduction was performed using tetrahydroxydiboron [B2(OH)4] as the reductant and 4,4′-bipyridine as the organocatalyst and could be completed within 5 min at room temperature. Under optimal conditions, nitroarenes with sensitive functional groups, such as vinyl, ethynyl, carbonyl, and halogen, were converted into the corresponding anilines with excellent selectivity while avoiding the undesirable reduction of the sensitive functional groups.

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Transition-Metal-Free Borylation of Aryl Bromide Using a Simple Diboron Source

Cited by 10 publications

References 56 publications

Role of N, N′‐Diboryl‐4, 4′‐bipyridinylidene in the Transition‐Metal‐Free Borylation of Aryl Halides and Direct C−H Arylation of Unactivated Benzene

Role of N, N′‐Diboryl‐4, 4′‐bipyridinylidene in the Transition‐Metal‐Free Borylation of Aryl Halides and Direct C−H Arylation of Unactivated Benzene

Replacement of Less-Preferred Dipolar Aprotic and Ethereal Solvents in Synthetic Organic Chemistry with More Sustainable Alternatives

Metal-Free, Rapid, and Highly Chemoselective Reduction of Aromatic Nitro Compounds at Room Temperature

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