Zinc‐Mediated Efficient and Selective Reduction of Carbonyl Compounds

Mandal, Tirtha; Jana, Snehasish

doi:10.1002/ejoc.201700887

Cited by 28 publications

(19 citation statements)

References 61 publications

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“…Alcohol spectral data were identical to those reported in the literature. [63] Electrolyses: Synthesis of γ-Butyrolactone (4,5-Diphenyl-5-(trifluoromethyl)dihydrofuran-2(3H)-one).…”

Section: Electrolyses: Synthesis Of Thionesmentioning

confidence: 99%

Cathodic Behaviour of Dicationic Imidazolium Bromides: The Role of the Spacer

et al. 2019

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The cathodic reduction of dicationic imidazolium bromides, whose spacer is either an aliphatic chain or a xylyl group, leads to the formation of the corresponding N‐heterocyclic carbenes (NHCs), which were isolated as the corresponding thiones, after reaction with elemental sulfur. The behaviour of the dications was compared with the corresponding monocations. The behaviour of dicarbenes depends on the nature of the spacer. This study evidenced that dicarbenes deriving from xylyl dications are less stable than the corresponding aliphatic ones (giving lower yields in thiones), due to a debenzylation reaction. On the other hand, the yields in thiones starting from aliphatic dications are higher than the corresponding monocations, suggesting a cooperative reduction at the electrode of the two imidazolium moieties. The cathodic process was confirmed using the co‐electrogenerated hydrogen to reduce 2,2,2‐trifluoroacetophenone to the corresponding alcohol.

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“…Alcohol spectral data were identical to those reported in the literature. [63] Electrolyses: Synthesis of γ-Butyrolactone (4,5-Diphenyl-5-(trifluoromethyl)dihydrofuran-2(3H)-one).…”

Section: Electrolyses: Synthesis Of Thionesmentioning

confidence: 99%

Cathodic Behaviour of Dicationic Imidazolium Bromides: The Role of the Spacer

et al. 2019

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“…Similarly, both of the alkylsilanes Et 3 SiH and Me 2 PhSiH turned out to be inappropriate reagents for our system (Table 1, entries 11 and 12). 11 This result is sufficient to infer that the electron transfer from Zn* to the aldehyde generates a reactive alkoxy radical intermediate that subsequently cooperates with silane, and that then results in the corresponding reduced benzyl alcohol as the major product after an appropriate workup procedure. These observations strongly suggest that the presence of a polar bond such as the O Si bond in silane substrates is required for effective reduction of carbonyls by highly active zinc.…”

Section: Notementioning

confidence: 91%

“…

The reduction of carbonyl compounds has been generally considered to be a fundamental protocol for the preparation of the corresponding alcohols. 11 Inspired by the above results, we were interested in exploring the nature of highly active zinc (Zn*) in the hydrosilylation of carbonyl compounds. 1 Aside from this protocol, metal-hydride, 2 boron-based reagents, 3 and bio-catalytic reduction 4 are also considered to be suitable methodologies.

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mentioning

confidence: 99%

“…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. 11 Inspired by the above results, we were interested in exploring the nature of highly active zinc (Zn*) in the hydrosilylation of carbonyl compounds. Furthermore, the zinc-based reduction protocol could be readily extended to hydrosilylation of carbonyl compounds, thereby providing the corresponding alcohols.…”

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confidence: 99%

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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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“…Based on literature precedent, catalysts generally categorized into phase transfer catalyst, metal/transition metals and enzyme and protein based catalyst ( Fig. 1) [88][89][90][91][92][93][94][95][96][97][98].…”

Section: Type Of Catalystsmentioning

confidence: 99%

One Pot and Two Pot Synthetic Strategies and Biological Applications of Epoxy-Chalcones

Farooq

Ngaini

2020

Chemistry Africa

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Epoxy chalcone is a heterocyclic molecule and an important precursor for the synthesis of biologically active compounds. This mini-review is elucidating the synthetic strategies of chalcone epoxide via one pot and two pot routes including nature of reactants, nature of catalyst and variety of catalyst to improve yield of desired product, biological applications and advantages and drawbacks of these synthetic strategies. One pot route has wide variety of reactants and efficient one is the condensation of aldehyde and ketone. However, two pot route is consisted of chalcone synthesis preceding to epoxy chalcone. The synthetic routes for the preparation of epoxy chalcone and the usage as a precursor for the synthesis of various organic molecules with biological application is comprehensively discussed. This review is outstanding in organic chemistry and pharmaceutical industries to produce new molecules with various applications. Graphic AbstractO O

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Zinc‐Mediated Efficient and Selective Reduction of Carbonyl Compounds

Cited by 28 publications

References 61 publications

Cathodic Behaviour of Dicationic Imidazolium Bromides: The Role of the Spacer

Cathodic Behaviour of Dicationic Imidazolium Bromides: The Role of the Spacer

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

One Pot and Two Pot Synthetic Strategies and Biological Applications of Epoxy-Chalcones

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