Palladium-Catalyzed Alkynylation of Secondary α-Bromo Carbonyl Compounds via Stille Coupling

Kang, Jun Yong; Connell, Brian T.

doi:10.1021/jo200939u

Cited by 23 publications

(6 citation statements)

References 29 publications

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“…CuI, ligated by 8-hydroxyquinoline, has also been used as an active catalyst to facilitate the coupling of arylboronic acids with alkynyl bromides . Pd-catalyzed cross-couplings of alkynylsilane, alkynylboron, alkynylzinc, and alkynyltin reagents with aryl halides are also powerful methods to synthesize arylalkynes. Similarly, in situ generated alkynylcopper(I) intermediates are also used as coupling partners in Pd-catalyzed Sonogashira couplings co-catalyzed by Cu-salts .…”

Section: Resultsmentioning

confidence: 99%

General Copper-Catalyzed Coupling of Alkyl-, Aryl-, and Alkynylaluminum Reagents with Organohalides

et al. 2016

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We report the first example of a very general Cu-catalyzed cross-coupling of organoaluminum reagents with organohalides. The reactions proceed for the couplings of alkyl-, aryl-, and alkynylaluminum reagents with aryl and heteroaryl halides and vinyl bromides, affording the cross-coupled products in good to excellent yields. Both primary and secondary alkylaluminum reagents can be utilized as organometallic coupling partners. These reactions are not complicated by β-hydride elimination, and as a result rearranged products are not observed with secondary alkylaluminum reagents even for couplings with heteroaryl halides under "ligand-free" conditions. Radical clock experiment with a radical probe and relative reactivity study of Ph3Al with two haloarenes, 1-bromonaphthalene and 4-chlorobenzonitrile, having two different redox potentials indicates that the reaction does not involve free aryl radicals and radical anions as intermediates. These results combined with the result of the Hammett plot obtained by reacting Ph3Al with iodoarenes containing p-H, p-Me, p-F, and p-CF3 substituents, which shows a linear curve (R(2) = 0.99) with a ρ value of +1.06, suggest that the current transformation follows an oxidative addition-reductive elimination pathway.

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Section: Resultsmentioning

confidence: 99%

General Copper-Catalyzed Coupling of Alkyl-, Aryl-, and Alkynylaluminum Reagents with Organohalides

et al. 2016

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“…Connell and Kang succeeded in the Stille‐type cross‐coupling encompassing secondary alkyl bromide carbamoyl derivatives A as suitable partners of alkynylstannanes B (Scheme ). The resulting tertiary alkynyl carbonyl compounds C were obtained in moderate yields by heating a toluene solution of reactants with PdCl 2 (MeCN) 2 as the pre‐catalyst and the bulky Xphos as the key ligand.…”

Section: α‐Alkynylation Of α‐Haloamidesmentioning

confidence: 99%

The Fascinating Chemistry of α‐Haloamides

et al. 2020

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The aim of this review is to highlight the rich chemistry of α‐haloamides originally mainly used to discover new C−N, C−O and C−S bond forming reactions, and later widely employed in C−C cross‐coupling reactions with C(sp3), C(sp2) and C(sp) coupling partners. Radical‐mediated transformations of α‐haloamides bearing a suitable located unsaturated bond has proven to be a straightforward alternative to access diverse cyclic compounds by means of either radical initiators, transition metal redox catalysis or visible light photoredox catalysis. On the other hand, cycloadditions with α‐halohydroxamate‐based azaoxyallyl cations have garnered significant attention. Moreover, in view of the important role in life and materials science of difluoroalkylated compounds, a wide range of catalysts has been developed for the efficient incorporation of difluoroacetamido moieties into activated as well as unactivated substrates.

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“…First, radical B is facile to undergo atom transfer [39][40][41][42] or single electron oxidation [43][44][45][46] by transition metal or photocatalyst (k = 10 5 −10 9 M −1 s −1 ) 58,59 . Moreover, A would directly undergo metal-catalyzed (Pd, Cu) cross-coupling to give α-alkynylated carbonyl derivatives C in the presence of alkyne 60,61 .…”

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confidence: 99%

Unified and practical access to ɤ-alkynylated carbonyl derivatives via streamlined assembly at room temperature

Shu

2019

Commun Chem

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The development of a unified and straightforward method for the synthesis of ɤ-alkynylated ketones, esters, and amides is an unmet challenge. Here we report a general and practical protocol to access ɤ-alkynylated esters, ketones, and amides with diverse substitution patterns enabled by dual-catalyzed spontaneous formation of C sp3-sp3 and C sp3-sp bond from alkenes at room temperature. This directing-group-free strategy is operationally simple, and allows for the straightforward introduction of an alkynyl group onto ɤ-position of carbonyl group along with the streamlined skeleton assembly, providing a unified protocol to synthesize various ɤ-alkynylated esters, acids, amides, ketones, and aldehydes, from readily available starting materials with excellent functional group compatibility.

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Palladium-Catalyzed Alkynylation of Secondary α-Bromo Carbonyl Compounds via Stille Coupling

Abstract: A catalytic intermolecular cross-coupling reaction that couples secondary α-bromo carbonyl compounds with alkynylstannanes to form secondary alkynyl carbonyl compounds via palladium catalysis employing the XPhos ligand is described.

Cited by 23 publications

References 29 publications

General Copper-Catalyzed Coupling of Alkyl-, Aryl-, and Alkynylaluminum Reagents with Organohalides

General Copper-Catalyzed Coupling of Alkyl-, Aryl-, and Alkynylaluminum Reagents with Organohalides

The Fascinating Chemistry of α‐Haloamides

Unified and practical access to ɤ-alkynylated carbonyl derivatives via streamlined assembly at room temperature

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