Diborative Reduction of Alkynes to 1,2-Diboryl-1,2-Dimetalloalkanes: Its Application for the Synthesis of Diverse 1,2-Bis(boronate)s

Takahashi, Fumiya; Nogi, Keisuke; Sasamori, Takahiro; Yorimitsu, Hideki

doi:10.1021/acs.orglett.9b01622

Cited by 44 publications

(28 citation statements)

References 44 publications

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“…Diarylalkynes containing a thiophene ring also provided the desired products in high yields (2t-x). When a strong electron-withdrawing group is present on the para-position of the benzene ring, the boron in the benzyl group is unstable and is easily protonated [8,10,20]. This issue was encountered herein, and after many attempts (see Supplementary materials (online) for unsuccessful substrates), it was surprisingly found that 2y could be obtained in medium yield (35%) under the present conditions, though the Ac group on the meta-position of the benzene ring.…”

Section: Extension Of Substrate Scopementioning

confidence: 71%

“…In 2017, our group [9] developed a base-controlled highly selective protocol for the synthesis of vicinal diboronates from terminal alkyl alkynes via domino-borylation-protodeboronation (DBP) with stoichiometric base (Scheme 1c). In 2019, Yorimitsu's group [20] developed a technique for the diborative reduction of alkynes to 1,2-bisboronates (a mixture of threo-and erythro-configuration) with the alkali metal sodium in two steps (Scheme 1d). Vicinal diboronates are potentially effective intermediates for the construction of polyarylethanes and vicinal diols.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis of anti-vicinal diboronates from diarylethynes and B2pin2

et al. 2019

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Section: Extension Of Substrate Scopementioning

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Synthesis of anti-vicinal diboronates from diarylethynes and B2pin2

et al. 2019

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“…Recently we have been interested in the development of reductive transformations using diboron reagents . During our investigation, we found that sulfoxides were reduced to the corresponding sulfides by means of diborons.…”

Section: Methodsmentioning

confidence: 89%

B₂cat₂‐Mediated Reduction of Sulfoxides to Sulfides

2020

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An efficient and operationally simple method for the reduction of sulfoxides to sulfides has been developed using bis(catecholato)diboron (B 2 cat 2 ) as a reducing agent. The present method accommodates various functional groups which are generally prone to reduction: halides, alkynes, Organosulfur compounds have occupied important positions as bioactive entities, functional materials, and useful building blocks or reagents in organic synthesis. [1] Among organosulfur compounds, sulfoxides have attracted attention of synthetic chemists because of the unique reactivity as is seen in Swern oxidation [2] and Pummerer-type reactions. [3] Besides these classical reactions, sulfoxides are also utilized in asymmetric transformations as chiral auxiliaries. [4] Moreover, owing to the coordination ability to transition metals, sulfoxides promote catalytic C-H functionalizations as directing groups. [5] After these reactions, the sulfoxide moiety can be removed, which often accompanies the reduction of sulfoxides to sulfides and subsequent desulfurization. From that perspective, reduction of sulfoxides to sulfides is a simple yet important process in organic synthesis. [6] Although there are many reports on reduction of sulfoxides by means of metal hydrides [7] or low-valent transition metals, [8] these reactions intrinsically suffer from competing reduction of other functionalities such as carbonyls. Sulfur(II) compounds [9] and phosphines [10] are also known to promote the reduction of sulfoxides, but they often encounter purification problems. In the former case, separation of the resulting sulfide products from the remaining sulfur(II) reductants such as thiols and sulfides can be problematic. The latter faces the formation of phosphine oxides as by-products that are tedious to remove. Efficient methods achieving good functional group tolerance and facile purification of the products are of high demand.Recently we have been interested in the development of reductive transformations using diboron reagents. [11] During our investigation, we found that sulfoxides were reduced to the corresponding sulfides by means of diborons. Although there are two reports on the reduction of sulfoxides with bis(pinacolato)diboron (B 2 pin 2 ) as a deoxygenating reagent, [12] catalysts, long [a]

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“…More recently, Nogi and Yorimitsu have developed the diborative reduction of alkynes towards 1,4‐diboratabutadiene dianions 15 , by means of B 2 pin 2 and alkali metals (Scheme 12). [27] A possible reaction mechanism has been suggested by the authors considering that the electron reduction of the alkyne would generate radical anion that further react with B 2 pin 2 to form borate intermediates.…”

Section: Synthesis Of α‐Monoboryl Carbanions/borata‐alkenesmentioning

confidence: 99%

Borata‐Alkene Species as Nucleophilic Reservoir

2021

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α‐Monoboryl anions show remarkable stability due to the valence deficiency of the adjacent three‐coordinate boron center and can be expressed as its resonance form, the borata‐alkene systems [R2B=CH2]−. The diversity of synthetic approaches as well as the properties of the C=B bond are disclosed in this review, dealing with both electronic and structural properties of the boryl moieties involved. Full characterization in solid state by X‐ray diffraction demonstrated the short distances between B and C, as a consequence of the boron ylide character in the boron‐stabilized carbanions. This review includes a collection of C−B length distances as well as 11B NMR data that can be useful for diagnostic evidence of the partial boron‐carbon double‐bond character. Natural bond orbital (NBO) analysis on DFT computed structures also supports and justifies the borata‐alkene character. The reactivity of the C=B bond acting as nucleophilic synthon is unveiled through extensive electrophilic trapping examples. The homologation protocols with diborylmethane, via single carbon chain extension, involves a facile introduction of the C(sp3)−B bonds, which can be subsequently transformed into functionalized target products, containing C−O, C−N or C−C bonds.

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Diborative Reduction of Alkynes to 1,2-Diboryl-1,2-Dimetalloalkanes: Its Application for the Synthesis of Diverse 1,2-Bis(boronate)s

Cited by 44 publications

References 44 publications

Synthesis of anti-vicinal diboronates from diarylethynes and B2pin2

Synthesis of anti-vicinal diboronates from diarylethynes and B2pin2

B₂cat₂‐Mediated Reduction of Sulfoxides to Sulfides

Borata‐Alkene Species as Nucleophilic Reservoir

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Diborative Reduction of Alkynes to 1,2-Diboryl-1,2-Dimetalloalkanes: Its Application for the Synthesis of Diverse 1,2-Bis(boronate)s

Cited by 44 publications

References 44 publications

Synthesis of anti-vicinal diboronates from diarylethynes and B2pin2

Synthesis of anti-vicinal diboronates from diarylethynes and B2pin2

B2cat2‐Mediated Reduction of Sulfoxides to Sulfides

Borata‐Alkene Species as Nucleophilic Reservoir

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B₂cat₂‐Mediated Reduction of Sulfoxides to Sulfides