Open-air oxidative Heck reactions at room temperature

Enquist, Per-Anders; Lindh, Jonas; Nilsson, Peter; Larhed, Mats

doi:10.1039/b517152k

Cited by 79 publications

(41 citation statements)

References 32 publications

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“…All the products were characterized by 1 H NMR and MS and compared with the literature values. [3][4][5] Reusability Study of the Catalyst After completion of the reaction, the catalyst was filtered and washed with ethyl acetate, followed by methanol and acetone and air dried. The recovered catalyst was employed in the next run.…”

Section: General Procedures For the Oh Reactionmentioning

confidence: 99%

“…[1][2][3][4][5] This is mainly because of the large diversity of readily accessible arylboronic acids, their moistureand air-stability, low toxicity and easy removal of the boron-derived by-products coupled with the high chemo-and regioselectivity of the reaction. The oxidative Heck reaction was first discovered by Heck using a stoichiometric amount of palladium salts [1] and subsequently its catalytic version was developed by Uemura, [2] Mori [3] and Jung et al [4] using palladium salts in presence of a co-oxidant.…”

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confidence: 99%

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Highly Efficient and Reusable Polyaniline‐Supported Palladium Catalysts for Open‐Air Oxidative Heck Reactions under Base‐ and Ligand‐Free Conditions

Likhar

Roy

et al. 2008

Adv Synth Catal

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Section: General Procedures For the Oh Reactionmentioning

confidence: 99%

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confidence: 99%

Highly Efficient and Reusable Polyaniline‐Supported Palladium Catalysts for Open‐Air Oxidative Heck Reactions under Base‐ and Ligand‐Free Conditions

Likhar

Roy

et al. 2008

Adv Synth Catal

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“…10 When this Mizoroki-Heck-type reaction was carried out with palladium catalyst, nitrogen 11,12 or phosphine-based 13 compounds were generally employed as the ligand. Therefore, ligand-free condition capable of showing high catalytic activity and selectivity is required.…”

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confidence: 99%

“…Various new methods have been attempted including a variety of transition metal catalysts (Pd, 5 Ni, 6 Rh, 7,8 and Ru 9 ), base-free condition and microwave irradiation. 10 When this Mizoroki-Heck-type reaction was carried out with palladium catalyst, nitrogen 11,12 or phosphine-based 13 compounds were generally employed as the ligand. Therefore, ligand-free condition capable of showing high catalytic activity and selectivity is required.…”

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confidence: 99%

“…The para-substituted substrates such as 4-methylphenylboronic acid (1b), 4-ethylphenylboronic acid (1c) and 4-methoxyphenylboronic acid (1d) also afforded the coupled products in moderate to high yields (entries 4-9). The steric demanding substrate 2-methylphenylboronic acid (1e) showed slightly lower yields (55 ~ 61%) (entries [10][11][12]. Attempts to couple with the meta-substituted 2-tolylboronic acid (1f) resulted in reasonable yields (entries [13][14][15].…”

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Ligand-free Palladium-Catalyzed Mizoroki-Heck-type Reaction of Arylboronic Acids and Alkenes Using Silver Cation

Song¹,

Park²,

Oh³

et al. 2010

Bulletin of the Korean Chemical Society

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Transition metal-catalyzed C-C bond formation has been widely used in organic synthesis.1 Among this class of reactions, the coupling reaction using organoboronic acid has been intensively studied due to organoboronic acid's advantages of stability to air and moisture, low toxicity and easy availability. 2One of the most established reactions is Suzuki cross coupling which is the palladium-catalyzed reaction of arylboronic acid and aryl halides.3,4 However, the reaction of arylboronic acid and alkene to afford the Mizoroki-Heck-type product has received less attention, even though this reaction condition is halide free and milder than the original Mizoroki-Heck reaction, which employed aryl halides instead of arylboronic acid. Various new methods have been attempted including a variety of transition metal catalysts (Pd, 5 Ni, 6 Rh,7,8 and Ru 9 ), base-free condition and microwave irradiation.10 When this Mizoroki-Heck-type reaction was carried out with palladium catalyst, nitrogen 11,12 or phosphine-based 13 compounds were generally employed as the ligand. Therefore, ligand-free condition capable of showing high catalytic activity and selectivity is required.It is well established that silver cation can work as an oxidant in the Pd(II) catalytic system. 14 However, there are very few examples of the use of silver cations in the palladium-catalyzed Heck-type reaction of arylboronic acid and alkenes. 15 Here, we report silver cation-mediated Mizoroki-Heck-type reaction to afford the desired product with high yield and high selectivity under ligand-free condition.We selected a standard Mizoroki-Heck-type reaction, with the phenylboronic acid (1a) and the electron-poor olefin n-butyl acrylate (2a), as an appropriate first test reaction. The results are summarized in Table 1. The coupling reactivity was first investigated with a variety of oxidants or bases. We found that the reactivity and selectivity in favor of the desired product 3aa was dependent of the nature of the oxidant or base. Among the oxidants and bases screened, AgOAc afforded the desired product in high yield and with high selectivity (entry 1). Other silver oxidants such as Ag2CO3 and Ag2O gave low yields (entries 2 and 3), while Ag2SO4 or benzoquinone, which is one of the most frequently used oxidants, produced very low yields (entries 4 and 5). The reaction using K3PO4 showed low conversion and afforded a Michael-type addition product as a major one, although at low yield (entry 6). Satoh and Miura reported that K3PO4 afforded a Michael-type addition product as a major output in the presence of phosphite ligand. 16 Carbonate bases afforded a trace amount of the desired product (entries 7-9). When phosphite was employed as a ligand, the reactivity and selectivity were not improved (entry 10). Moreover, triphenylphosphine produced 30% of the byproduct which was derived from the homocoupling of phenylboronic acid (entry 11). All the tested palladium sources showed good yields (entries 1, 12, 13 and 14). A variety of solvents were screened. The ...

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Phenol, 2,4-Bis(1,1-Dimethylethyl)-, 1,1′,1″-Phosphite

Lee

2010

Encyclopedia of Reagents for Organic Synthesis

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Open-air oxidative Heck reactions at room temperature

Cited by 79 publications

References 32 publications

Highly Efficient and Reusable Polyaniline‐Supported Palladium Catalysts for Open‐Air Oxidative Heck Reactions under Base‐ and Ligand‐Free Conditions

Highly Efficient and Reusable Polyaniline‐Supported Palladium Catalysts for Open‐Air Oxidative Heck Reactions under Base‐ and Ligand‐Free Conditions

Ligand-free Palladium-Catalyzed Mizoroki-Heck-type Reaction of Arylboronic Acids and Alkenes Using Silver Cation

Phenol, 2,4-Bis(1,1-Dimethylethyl)-, 1,1′,1″-Phosphite

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