Synthesis of Cyclic 1-Alkenylboronates via Zr-Mediated Double Functionalization of Alkynylboronates and Sequential Ru-Catalyzed Ring-Closing Olefin Metathesis

Nishihara, Yasushi; Suetsugu, Masato; Saito, Daisuke; Kinoshita, M.; Iwasaki, Masayuki

doi:10.1021/ol400896u

Cited by 20 publications

(43 citation statements)

References 76 publications

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“…9-Aminophenanthrene 1 was oxidized to tetrabenzocarbazole 2 in 94% yield. Reaction of 2 with Pd(OAc) 2 /tricyclohexylphosphine provided singly fused product 3 in 63% yield 29 . The twisted conformation of 3 was unambiguously elucidated by X-ray diffraction analysis ( Supplementary Fig.…”

Section: Resultsmentioning

confidence: 99%

Nitrogen-embedded buckybowl and its assembly with C60

et al. 2015

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Curved π-conjugated molecules have attracted considerable interest because of the unique properties originating from their curved π surface. However, the synthesis of such distorted molecules requires harsh conditions, which hamper easy access to heteroatom-containing curved π systems. Here we report the synthesis of a π-extended azacorannulene with nitrogen in its centre. The oxidation of 9-aminophenanthrene provides tetrabenzocarbazole, which is converted to the azabuckybowl through palladium-catalysed intramolecular coupling. The electron-donating nature and curved π surface of the azabuckybowl enable its tight association with C60 in solution and solid states. High charge mobility is observed for the azabuckybowl/C60 assembly. This compound may be of interest in the fields of curved π systems as fullerene hosts, anisotropic π donors and precursors to nitrogen-containing nanocarbon materials.

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Section: Resultsmentioning

confidence: 99%

Nitrogen-embedded buckybowl and its assembly with C60

et al. 2015

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“…Alkenylboronates are synthetically versatile building blocks. Despite many reports of the synthesis of alkenylboronates, regio- and stereoselective synthesis of tetrasubstituted alkenylboronates, which are useful precursors for tetrasubstituted alkenes, is particularly challenging. − Suginome et al reported seminal examples of the regio- and stereoselective synthesis of tetrasubstituted alkenylboronates through nickel- or palladium-catalyzed intramolecular boryl transfer to a CC triple bond using substrates containing a reactive boryl moiety (Scheme a) . Soon after, palladium- and nickel-catalyzed intermolecular carboboration of alkynes was reported (Scheme b). − More recently, copper-catalyzed borylalkylation of alkynes through three-component coupling with bis(pinacolato)diboron [(Bpin) 2 ] and alkyl halides has emerged as a powerful method to furnish tetrasubstituted alkenylboronates (Scheme c). , Three main events proceeded in a well-ordered manner in this one-pot, three-component reaction: (1) generation of a borylcopper species from a copper alkoxide catalyst and (Bpin) 2 ; (2) regioselective borylcupration of alkynes to afford alkenylcopper intermediate 1 ; and (3) alkylation of 1 with alkyl halides.…”

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confidence: 99%

Ligand-Enabled, Copper-Catalyzed Regio- and Stereoselective Synthesis of Trialkylsubstituted Alkenylboronates from Unactivated Internal Alkynes

2016

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We report the first copper-catalyzed regio- and stereoselective borylalkylation of dialkylsubstituted internal alkynes with bis(pinacolato)diboron and alkyl halides. A catalytically generated borylcopper species containing a novel π-accepting N-heterocyclic carbene ligand chemoselectively reacted with unactivated internal alkynes over alkyl halides. The intermediate alkenylcopper species subsequently reacted with alkyl halides, affording the desired products. The copper catalyst differentiated steric demands between the two aliphatic substituents on the C≡C triple bond of the alkyne substrates to exhibit high regioselectivity from a wide range of alkyne/alkyl halide combinations. This method is useful for the straightforward synthesis of trialkylsubstituted alkenylboronates, i.e., versatile precursors for tetrasubstituted alkenes containing three or four different alkylsubstituents, which are difficult to synthesize by other methods.

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“…[63] Moreover, the cyclic alkenyl boron compounds were also synthesized from this zirconacyclopentene employing the novel ring-closing metathesis with Grubbs catalyst. [64] First, they treated the alkynyl boronate with Negishi's reagent and tributyl phosphine to prepare zirconacyclopropene 61. This produces the zirconacyclopentene 63 via reaction with allyl ether, that undergoes subsequent β-oxygen elimination, and further, a second allylation produces tetrasubstituted alkenyl boronate 64 with two allyl moieties (Scheme 14d).…”

Section: Zirconium Metallacyclementioning

confidence: 99%

Zirconium Catalyzed Transformations Using Organoboron

et al. 2022

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Organoboron compounds have extreme potential for organic synthesis. Ready functionalization of organoboron intrigued people to develop various protocols for their synthesis. Over the last several decades, there has been a substantial development in synthesizing new organoboron compounds using transition metals. Among various transition metals, zirconium has also been found to catalyze diverse reactions of organoboron. The zirconium chemistry has become more popular with the development of zirconium metallocenes, particularly bis(cyclopentadienyl)zirconocene chloride hydride, the wellknown Schwartz reagent. These zirconium metallocenes possess a significant role in hydrozirconation, hydroboration, hydrogenation, carbozirconation, and a promising tri-n-butyl tin hydride alternative. This minireview focuses on the various transformations of organoboron employing zirconium catalysts that have been developed so far.

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Synthesis of Cyclic 1-Alkenylboronates via Zr-Mediated Double Functionalization of Alkynylboronates and Sequential Ru-Catalyzed Ring-Closing Olefin Metathesis

Cited by 20 publications

References 76 publications

Nitrogen-embedded buckybowl and its assembly with C60

Nitrogen-embedded buckybowl and its assembly with C60

Ligand-Enabled, Copper-Catalyzed Regio- and Stereoselective Synthesis of Trialkylsubstituted Alkenylboronates from Unactivated Internal Alkynes

Zirconium Catalyzed Transformations Using Organoboron

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