Pd-catalyzed selective hydrosilylation of aryl ketones and aldehydes

Chouthaiwale, Pandurang V.; Rawat, Varun; Sudalai, Arumugam

doi:10.1016/j.tetlet.2011.10.155

Cited by 20 publications

(14 citation statements)

References 22 publications

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“…Hydrosilanes are often used for the reduction of carbonyl compounds, because they are easy to handle and inexpensive. Noble metals such as Rh, Ag, Au, Re, Ir 4,] Pd and Co can be utilized as catalysts to accomplish these transformations, but they have the drawbacks of high costs and toxicity. More inexpensive and greener alternatives are Cu, Fe, Zn, Mn matal catalysts and other non‐metal catalysts.…”

Section: Methodsmentioning

confidence: 99%

I₂‐Initiated Reduction of α‐Ketoesters with a Hydrosilane

Jiang

Xiao

2020

ChemistrySelect

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Molecular iodine is widely used because of its environmental friendliness and easy operation. In this work, a novel reduction system involved molecular iodine and a hydrosilane for the reduction of α-ketoesters to the corresponding α-hydroxy esters has been developed. And the I 2 -HSiEt 3 system showed its mild reaction conditions and high efficiency.Hydrosilanes are often used for the reduction of carbonyl compounds, because they are easy to handle and inexpensive. Noble metals such as Rh, [1] Ag, [2] Au, [2] Re, [3] Ir 4,] Pd [5] and Co [6] can be utilized as catalysts to accomplish these transformations, but they have the drawbacks of high costs and toxicity. More inexpensive and greener alternatives are Cu, [2] Fe, [7] Zn, [8] Mn [9] matal catalysts and other non-metal catalysts. The reported non-metal catalysts mainly include acid, [10] base, [11] fluoride ions [12] and boron catalyst [13] (Scheme 1). In recent years, the metal free reactions involving molecular iodine have received considerable attention owing to their low toxicity, low cost, high tolerance to air and moisture and easy operation. For example, molecular iodine has been proved successful in crossdehydrogenative coupling reactions, [14] oxidative amination reactions, [15] oxidative cross-coupling reactions, [16] oxidative decarboxylative amination, [17] 2-sulfonylation of indoles, [18] formal [3 + 2] cycloaddition [19] and formation of lactams via selective oxidation of cyclic secondary and tertiary amines. [20] We hypothesized that molecular iodine can promote the reaction of hydrosilanes and carbonyl compounds to form hydroxyl compounds.The first example of transformation of carbonyl compounds using I 2 -hydrosilane system was reported by C. Palomo et al. in 1985. They used iodine and 1,1,3,3-tetramethyldisiloxane (TMDS) to produce alkyl iodides from carbonyl compounds [21] (Scheme 2(a)). Then, in 2010, J. S. Yadav et al. reported a smooth reductive etherification of carbonyl compounds in the presence of I 2 and polymethylhydrosiloxane (PMHS) [22] (Scheme 2(b)). In this work, we reported a metal free reduction of carbonyl compounds (α-ketoesters) with molecular iodine and a hydrosilane (triethylsilane, HSiEt 3 ) to form hydroxyl compounds (Scheme 2(c)).The commonly used triethylsilane [3] was utilized as reductant to test our hypothesis. Initially, 0.3 equiv. of I 2 and 2.0 equiv. of HSiEt 3 were used to reduce carbonyl compounds (1.0 equiv.) in 2.0 mL of dichloromethane (DCM) at room temperature for 30 minutes (Scheme 3). The major products of benzaldehyde and acetophenone were benzyl iodine (1, 43 % yield) and 1-iodo-1-phenylethane (2, 32 % yield) respectively (Scheme 3(a) and 3(b)). This is consistent with the reaction of I 2 -TMDS system. [21] However, methyl 2-oxo-2-phenylacetate (3 a), a ketone bearing an electron-withdrawing ester group, gave [a] Dr. Scheme 1. Metal free reduction of carbonyl compounds involving hydrosilanes Scheme 2. Transformations of carbonyl compounds using I 2 -hydrosilane ChemistrySelect Communications

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Section: Methodsmentioning

confidence: 99%

I₂‐Initiated Reduction of α‐Ketoesters with a Hydrosilane

Jiang

Xiao

2020

ChemistrySelect

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“…Similarly, the mechanism for the Pd‐catalyzed reduction of α‐keto amides might be similar to that of the metal‐catalyzed hydrosilylation of simple ketones 15. We assume that the K 2 PdCl 4 will react with PMHS to give Pd(0) 5 and H 2 gas, then 5 will undergo oxidative addition with PMHS to give Pd hydride 8 .…”

Section: Resultsmentioning

confidence: 99%

Chemoselective Reductive Deoxygenation and Reduction of α‐Keto Amides by using a Palladium Catalyst

Mamillapalli

Sekar

2015

Adv Synth Catal

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Ap alladium catalyst is used to synthesize 2,N-diphenylacetamides and a-hydroxya mides from readily available a-keto amides by chemoselective reductived eoxygenation and chemoselective reduction using polymethylhydrosiloxane (PMHS). This methodology has the important advantage in that, just by changing the reactions olvent and temperature,t he reaction can be switched from reductived eoxygenation to reduction of a-keto amides. Using this protocol, several biologicallyi mportant 2,N-diphenylacetamide derivatives and a-hydroxy amides were synthesized.

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“…In addition, an emerging tool is reduction of the carbonyl group in the presence of a transition‐metal catalyst. Numerous transition‐metals have been extensively examined to successfully complete this transformation, especially in transfer hydrogenation which is a safe and operationally simple protocol utilizing either element hydrogen or metal‐hydrides. 5i, j…”

Section: Methodsmentioning

confidence: 99%

Ligand‐Free Hydrosilylation of Aldehydes Mediated by Highly Active Zinc Metal

Joo

Kim

2018

Bulletin Korean Chem Soc

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The reduction of carbonyl compounds has been generally considered to be a fundamental protocol for the preparation of the corresponding alcohols. Catalytic hydrogenation of carbonyls has long been a traditional method for achieving this. 1 Aside from this protocol, metal-hydride, 2 boron-based reagents, 3 and bio-catalytic reduction 4 are also considered to be suitable methodologies. In addition, an emerging tool is reduction of the carbonyl group in the presence of a transition-metal catalyst. Numerous transition-metals have been extensively examined to successfully complete this transformation, 5 especially in transfer hydrogenation which is a safe and operationally simple protocol utilizing either element hydrogen or metal-hydrides. 5i, j Along with these protocols, a zinc-based reduction process has been extensively applied for reduction of carbonyl compounds, mainly due to the environmental friendliness and economic benefits. Furthermore, the zinc-based reduction protocol could be readily extended to hydrosilylation of carbonyl compounds, thereby providing the corresponding alcohols. Since the first report by Caubere, 6 and pioneering work by Minoun, 7 it has emerged as an attractive synthetic method to reduce carbonyl compounds. 8 When using this approach, zinc complexes such as zinc acetate and diethylzinc, which are particularly activated by nitrogen-chelating ligands, have frequently been used as pre-catalysts. In early studies of zinc-catalyzed hydrosilylation of aldehydes and ketones, both zinc(II) salt and zinc (0) powder worked well to obtain the corresponding alcohols in the presence of metal-hydride and chlorotrimethylsilane. In 2009, Nishiyama et al. reported a successful method for hydrosilylation of carbonyl compounds using zinc acetate as a catalyst without any assistance from ligands. 9 From a synthetic point of view, reactions of carbonyl compounds with zinc metal also have value in novel applicability. A recent study by Len et al. used zinc metal and carbonyl compound for selective reductive pinacol coupling. 10 The reaction was carried out with zinc metal and NH 4 Cl in an aqueous media, yielding the diols as a major product along with small amounts of reduced alcohols. More recently, Dash's group has described a relatively simple process for selective reduction of carbonyls using a combination of zinc metal-powder with an aqueous NH 4 Cl solution as a proton source in THF. The corresponding product alcohols were exclusively produced along with a trace amount of the pinacol product diols (Scheme 1). 11 Inspired by the above results, we were interested in exploring the nature of highly active zinc (Zn*) in the hydrosilylation of carbonyl compounds. To investigate the potential of our strategy, carbonyl compounds were treated with a mixture of highly active zinc and silane in the absence of any other ligands. Herein, we describe the successful development of Zn*-mediated hydrosilylation of aldehydes and ketones, producing the corresponding alcohols as a major product.To elucidate our stra...

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Pd-catalyzed selective hydrosilylation of aryl ketones and aldehydes

Cited by 20 publications

References 22 publications

I₂‐Initiated Reduction of α‐Ketoesters with a Hydrosilane

I₂‐Initiated Reduction of α‐Ketoesters with a Hydrosilane

Chemoselective Reductive Deoxygenation and Reduction of α‐Keto Amides by using a Palladium Catalyst

Ligand‐Free Hydrosilylation of Aldehydes Mediated by Highly Active Zinc Metal

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Pd-catalyzed selective hydrosilylation of aryl ketones and aldehydes

Cited by 20 publications

References 22 publications

I2‐Initiated Reduction of α‐Ketoesters with a Hydrosilane

I2‐Initiated Reduction of α‐Ketoesters with a Hydrosilane

Chemoselective Reductive Deoxygenation and Reduction of α‐Keto Amides by using a Palladium Catalyst

Ligand‐Free Hydrosilylation of Aldehydes Mediated by Highly Active Zinc Metal

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I₂‐Initiated Reduction of α‐Ketoesters with a Hydrosilane

I₂‐Initiated Reduction of α‐Ketoesters with a Hydrosilane