Boron-Masking Strategy for the Selective Synthesis of Oligoarenes via Iterative Suzuki−Miyaura Coupling

Noguchi, Hiroyoshi; Hojo, Kosho; Suginome, Michinori

doi:10.1021/ja067975p

Cited by 378 publications

(185 citation statements)

References 19 publications

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“…Continuation of the iterative process is then enabled by subsequent deprotection of the masked boronic acid. A variety of protecting groups have been explored for these purposes, most notably N-methyliminodiacetic acid (MIDA) (6, 11-13) and 1,8-diaminonaphthalene (BDAN) (14)(15)(16)(17)(18). In addition to these reagents, isolated reports have used organotrifluoroborates (RBF 3 K) (19) and catecholboronates (20) as protected boronic acid equivalents in specific settings.…”

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confidence: 99%

Protecting group-free, selective cross-coupling of alkyltrifluoroborates with borylated aryl bromides via photoredox/nickel dual catalysis

Yamashita

Tellis

Molander

2015

Proc. Natl. Acad. Sci. U.S.A.

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Orthogonal reactivity modes offer substantial opportunities for rapid construction of complex small molecules. However, most strategies for imparting orthogonality to cross-coupling reactions rely on differential protection of reactive sites, greatly reducing both atom and step economies. Reported here is a strategy for orthogonal cross-coupling wherein a mechanistically distinct activation mode for transmetalation of sp3-hybridized organoboron reagents enables C-C bond formation in the presence of various protected and unprotected sp2-hybridized organoborons. This manifold has the potential for broad application, because orthogonality is inherent to the activation mode itself. The diversification potential of this platform is shown in the rapid elaboration of a trifunctional lynchpin through various transition metal-catalyzed processes without nonproductive deprotection or functional group manipulation steps.

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confidence: 99%

Protecting group-free, selective cross-coupling of alkyltrifluoroborates with borylated aryl bromides via photoredox/nickel dual catalysis

Yamashita

Tellis

Molander

2015

Proc. Natl. Acad. Sci. U.S.A.

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“…1,2 Chemoselectivity within systems containing two organoborons is typically achieved by a designed deactivation: (i) Highly effective p-orbital protecting group strategies developed by Burke (BMIDA) 3 and Suginome (BDAN) 4 render one organoboron unit unreactive towards transmetallation (Scheme 1a); 5,6 (ii) A unique selfactivation/protection mechanism developed by both Morken and Shibata allows chemoselectivity within geminal and vicinal diboron compounds (Scheme 1b); 7 and (iii) Crudden has shown that benzyl BPin species are unreactive in the absence of specific additives, allowing selective aryl/benzyl transmetallation (Scheme 1c). 8 Accordingly, current methods to achieve chemoselectivity rely upon employing one nucleophile that is unreactive towards transmetallation under the prevailing reaction conditions.…”

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confidence: 99%

Chemoselective Suzuki–Miyaura Cross‐Coupling via Kinetic Transmetallation

2016

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Chemoselective Suzuki-Miyaura cross-coupling generally requires a designed deactivation of one nucleophile towards transmetallation. Here we show that boronic acids can be chemoselectively reacted in the presence of ostensibly equivalently reactive boronic acid pinacol (BPin) esters by kinetic discrimination during transmetallation. Simultaneous electrophile control allows sequential chemoselective cross-couplings in a single operation in the absence of protecting groups.Chemoselective Suzuki-Miyaura cross-coupling of multinucleophile systems has emerged as a powerful synthetic strategy for chemical synthesis. (ii) A unique selfactivation/protection mechanism developed by both Morken and Shibata allows chemoselectivity within geminal and vicinal diboron compounds (Scheme 1b); 7 and (iii) Crudden has shown that benzyl BPin species are unreactive in the absence of specific additives, allowing selective aryl/benzyl transmetallation (Scheme 1c). Accordingly, current methods to achieve chemoselectivity rely upon employing one nucleophile that is unreactive towards transmetallation under the prevailing reaction conditions. In particular, selective discrimination of two arylboron nucleophiles is only achievable using a suitable protecting group strategy. 9,10Scheme 1. Nucleophile-selective Suzuki-Miyaura reactions.Here we report that the chemoselective cross-coupling of two seemingly equivalently reactive aryl organoboron compounds can be achieved by exploiting subtle differences in their respective rates of transmetallation (Scheme 1d).Elegant studies by Hartwig,11 Amatore and Jutand, 12 Schmidt, 13 and, recently, Denmark 14 have demonstrated the role of oxopalladium transmetallation in the Suzuki-Miyaura reaction. 15 As part of his seminal study, Hartwig reported that boronic acids were observed to transmetallate ca. 45 times faster than the equivalent BPin ester using stoichiometric quantities of a dimeric oxopalladium complex and in a noncompetitive system. 11 Based on these data we questioned whether chemoselective cross-coupling of a boronic acid over a BPin ester might be possible via kinetic discrimination during transmetallation in a catalytic system. We initially independently assessed the relative rates of cross-coupling of boronic acid 1a and the equivalent BPin 1b with bromobenzene (2) under representative Suzuki-Miyaura reaction conditions (Scheme 2a).Scheme 2. Independent and competitive cross-couplings of boronic acid (1a/4a) vs. BPin (1b) with aryl bromide 2. Determined by HPLC analysis.These initial results suggested comparable reactivity of 1a and 1b, with both nucleophiles rapidly consumed at the same

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“…3 Miyaura borylation of Bdan-incorporated bromoarenes. When these novel molecules were subjected to SMC reaction, Bpin moiety reacted exclusively while the Bdan moiety remained intact.…”

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confidence: 99%

Differentiated Di- and Polyboron Compounds: Synthesis and Application in Successive Suzuki–Miyaura Coupling

2014

Synlett

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Boron-Masking Strategy for the Selective Synthesis of Oligoarenes via Iterative Suzuki−Miyaura Coupling

Cited by 378 publications

References 19 publications

Protecting group-free, selective cross-coupling of alkyltrifluoroborates with borylated aryl bromides via photoredox/nickel dual catalysis

Protecting group-free, selective cross-coupling of alkyltrifluoroborates with borylated aryl bromides via photoredox/nickel dual catalysis

Chemoselective Suzuki–Miyaura Cross‐Coupling via Kinetic Transmetallation

Differentiated Di- and Polyboron Compounds: Synthesis and Application in Successive Suzuki–Miyaura Coupling

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