Platinum-catalysed diborylation of arynes: synthesis and reaction of 1,2-diborylarenes

Yoshida, Hiroto; Okada, Kengo; Kawashima, Shota; Tanino, Kenji; Ohshita, Joji

doi:10.1039/b919407j

Cited by 81 publications

(33 citation statements)

References 54 publications

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“…[16] A plausible catalytic cycle for this annulation reaction is shown in Scheme 7 (based on the results shown in Scheme 6), with diborylstilbenes 1 a-1 c representing the 1,2diboryl reagents. The sole product was cis-stilbene derivative 4, which was obtained in 76 % yield.…”

Section: Resultsmentioning

confidence: 99%

Palladium‐Catalyzed Annulation of 1,2‐Diborylalkenes and ‐Arenes with 1‐Bromo‐2‐[(Z)‐2‐bromoethenyl]arenes: A Modular Approach to Multisubstituted Naphthalenes and Fused Phenanthrenes

Shimizu

Tomioka

Nagao

et al. 2012

Chemistry An Asian Journal

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(Z)-1,2-Diaryl-1,2-bis(pinacolatoboryl)ethenes underwent double-cross-coupling reactions with 1-bromo-2-[(Z)-2-bromoethenyl]arenes in the presence of [Pd(PPh(3))(4)] as a catalyst and 3 M aqueous Cs(2)CO(3) as a base in THF at 80 °C. The double-coupling reaction gave multisubstituted naphthalenes in good to high yields. Annulation of 1,2-bis(pinacolatoboryl)arenes with bromo(bromoethenyl)arenes in the presence of a catalyst system that consisted of [Pd(2)(dba)(3)] (dba=dibenzylideneacetone) and 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl (SPhos) under the same conditions produced fused phenanthrenes in good to high yields. The first annulation coupling occurred regiospecifically at the bromoethenyl moiety. This procedure is applicable to the facile synthesis of polysubstituted anthracenes, benzothiophenes, and dibenzoanthracenes through a double annulation pathway by using the corresponding dibromobis[(Z)-2-bromoethenyl]benzenes as diboryl coupling partners.

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Section: Resultsmentioning

confidence: 99%

Palladium‐Catalyzed Annulation of 1,2‐Diborylalkenes and ‐Arenes with 1‐Bromo‐2‐[(Z)‐2‐bromoethenyl]arenes: A Modular Approach to Multisubstituted Naphthalenes and Fused Phenanthrenes

Shimizu

Tomioka

Nagao

et al. 2012

Chemistry An Asian Journal

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“…Along with hydroboration, [1][2][3][4] transition-metalcatalyzed diboration [5] has become useful for the functionalization of unsaturated organic compounds. [6,7] This reaction is widely applicable to substrates such as alkynes [8,9] arynes, [10] alkenes, [11][12][13] carbenoids, [14,15] as well as diazo [16] and carbonyl compounds. [17][18][19][20] Although bis(catecholato)diborane(4) and bis(pinacolato)diborane(4) represent by far the most commonly employed diborane(4) species, the reaction is not restricted to their use.…”

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confidence: 99%

Unexpected Generation of Diastereomers by Double Diboration of a Dialkyne

Bauer

Braunschweig

Gruß

et al. 2011

Chemistry A European J

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During the last two decades, boron compounds have become established as versatile reagents in organic synthesis, and different methods have been developed for their preparation. Along with hydroboration, [1][2][3][4] transition-metalcatalyzed diboration [5] has become useful for the functionalization of unsaturated organic compounds. [6,7] This reaction is widely applicable to substrates such as alkynes [8,9] arynes, [10] alkenes, [11][12][13] carbenoids, [14,15] as well as diazo [16] and carbonyl compounds. [17][18][19][20] Although bis(catecholato)diborane(4) and bis(pinacolato)diborane(4) represent by far the most commonly employed diborane(4) species, the reaction is not restricted to their use. For instance, several diboranes(4) with interesting properties are derived from [2]borametalloarenophanes. The first example of this class of organometallic compound, the [2]boraferrocenophane 1, was prepared by Herberhold, Wrackmeyer and co-worker, [21] while the molecular structure along with an alternative synthesis was published by our group.[22] Subsequently, a series of [2]borametalloarenophanes has appeared. [23-28b] These ansa complexes show tilted molecular structures, thus featuring significant molecular strain. In 2006, we successfully exploited this ring strain in oxidative addition reactions of [2]borametalloarenophanes to low-valent platinum centers, affording[3]diboraplatinametalloarenophanes. In addition, we demonstrated the suitability of [2]borametalloarenophanes as diboranes(4) in the platinum-mediated diboration of alkynes to form [4]diboradicarbametalloarenophanes.[29] By expansion of this strategy, we also achieved the diboration of diazo compounds [16] and isocyanides.[30]Herein, we report on the two diastereomeric [4]diboradicarbaferrocenophanes 4 and 5, which were obtained by double diboration of the conjugated dialkyne 3 either by a platinum-mediated route employing the [2]boraferrocenophane 1 in the presence of [PtA C H T U N G T R E N N U N G (PEt 3 ) 3 ], or stoichiometrically by using the [3]diboraplatinaferrocenophane 2, directly (Scheme 1). In contrast to related transformations of monoalkynes, [29] monitoring the reaction progress by multinuclear NMR spectroscopy revealed the gradual disappearance of the starting materials, and the formation of two distinct compounds in benzene solution at elevated temperatures. Both species feature similar resonances in the 1 H, 11 B, and 13 C NMR spectra, which we rationalized by the generation of diastereomeric species. Complexes 4 and 5 were eventually isolated after workup as orange, moderately moisture-sensitive powders. The NMR spectroscopic data of both diastereomers are fully consistent with the presence of doubly bis(borylated), conjugated triene systems bearing two ferro-

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“…However, there are only a few metal-mediated borylations of arynes. 2,3 Recently, we discovered that arynes are spontaneously hydroborated by N-heterocyclic carbene boranes (NHCboranes). 4 Unlike most boranes, NHC-boranes are typically stable to air, moisture, and weak acids (Scheme 1).…”

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confidence: 99%

Hydroboration of Arynes Formed by Hexadehydro-Diels–Alder Cyclizations with N-Heterocyclic Carbene Boranes

2015

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Platinum-catalysed diborylation of arynes: synthesis and reaction of 1,2-diborylarenes

Abstract: Arynes are found to be facilely inserted into bis(pinacolato)diboron by using a platinum-isocyanide catalyst, affording diverse 1,2-diborylarenes, which can be converted into o-terphenyls via Suzuki-Miyaura coupling reaction.

Cited by 81 publications

References 54 publications

Palladium‐Catalyzed Annulation of 1,2‐Diborylalkenes and ‐Arenes with 1‐Bromo‐2‐[(Z)‐2‐bromoethenyl]arenes: A Modular Approach to Multisubstituted Naphthalenes and Fused Phenanthrenes

Palladium‐Catalyzed Annulation of 1,2‐Diborylalkenes and ‐Arenes with 1‐Bromo‐2‐[(Z)‐2‐bromoethenyl]arenes: A Modular Approach to Multisubstituted Naphthalenes and Fused Phenanthrenes

Unexpected Generation of Diastereomers by Double Diboration of a Dialkyne

Hydroboration of Arynes Formed by Hexadehydro-Diels–Alder Cyclizations with N-Heterocyclic Carbene Boranes

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