Improved Reactivity of Diiodosamarium by Catalysis with Transition Metal Salts

Machrouhi, Fouzia; Hamann, B.; Namy, Jean‐Louis; Kagan, Henri B.

doi:10.1055/s-1996-5547

Cited by 122 publications

(87 citation statements)

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“…However, with predominance of the lactone arising that a lactone is reactive in Barbier-type reactions with alkyl iodides. [9] However, the product of the reaction is the 5,5-from attack on the less hindered carbonyl group is predominant. In one case (entry 5) a single regioisomer was isolated.…”

Section: Resultsmentioning

confidence: 99%

“…[9] hydes mediated by samarium(II) compounds have been Disubstituted lactones are obtained in high yield (Table widely studied (reductions, pinacol couplings, Barbier-1). Grignard-type reactions etc.…”

Section: Introductionmentioning

confidence: 99%

“…[7] [8] [9] The lack of studies concerning the reactivity of samarium(II) compounds towards acid anhydrides is surprising.…”

Section: Introductionmentioning

confidence: 99%

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Barbier-Type Reactions of Cyclic Acid Anhydrides and Keto Acids Mediated by an SmI2-(NiI2-Catalytic) System – Preparation of Disubstituted Lactones

1998

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Cyclic acid anhydrides (succinic and glutaric anhydrides and some of their derivatives) undergo fast Barbier‐type reactions mediated by samarium diiodide in the presence of catalytic amounts of nickel diiodide (1 mol‐% with respect to SmI2), to give disubstituted lactones in high yields. Without NiI2 no reaction occurs. Various alkyl and allyl iodides can be used. In these reactions the formation of a samarium keto carboxylate intermediate is likely; as a matter of fact, keto carboxylic acids react under similar conditions to also yield disubstituted lactones. It is demonstrated that lactonisation occurs during hydrolysis of the reaction.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Barbier-Type Reactions of Cyclic Acid Anhydrides and Keto Acids Mediated by an SmI2-(NiI2-Catalytic) System – Preparation of Disubstituted Lactones

1998

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“…With the requisite starting material available, a study was carried out to find the best conditions for a samarium diiodide-promoted Barbier-type reaction of 38, and we found that nickel(II) iodide was the best additive 31) for this conversion to furnish the desired product in high yield. It is noteworthy that the samarium diiodide-promoted Barbier-type reaction of 38 led to the construction of a spiro [4,5] decane ring system, in which the hydroxyl group at the 8-position was fixed as only one diastereoisomeric form.…”

Section: )mentioning

confidence: 99%

Investigation of Innovative Synthesis of Biologically Active Compounds on the Basis of Newly Developed Reactions

Honda

2012

Chem. Pharm. Bull.

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Synthesis of biologically active compounds, including natural products and pharmaceutical agents, is an important and interesting research area since the large structural diversity and complexity of bioactive compounds make them an important source of leads and scaffolds in drug discovery and development. Many structurally and also biologically interesting compounds, including marine natural products, have been isolated from nature and have also been prepared on the basis of a computational design for the purpose of developing medicinal chemistry. In order to obtain a wide variety of derivatives of biologically active compounds from the viewpoint of medicinal chemistry, it is essential to establish efficient synthetic procedures for desired targets. Newly developed reactions should also be used for efficient synthesis of desired compounds. Thus, recent progress in the synthesis of biologically active compounds by focusing on the development of new reactions is summarized in this review article.

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“…[24][25][26][27] Though critical for success, the mechanistic role of Ni (II) was not known in these reactions. Recently it has been shown that SmI 2 reduces Ni(II) to Ni(0), and the reaction is then carried out through organometallic Ni(0) chemistry.…”

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confidence: 99%

Preparation and Use of Samarium Diiodide (SmI<sub>2</sub>) in Organic Synthesis: The Mechanistic Role of HMPA and Ni(II) Salts in the Samarium Barbier Reaction

Sadasivam

Choquette

Flowers

2013

JoVE

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Although initially considered an esoteric reagent, SmI 2 has become a common tool for synthetic organic chemists. SmI 2 is generated through the addition of molecular iodine to samarium metal in THF.1,2-3 It is a mild and selective single electron reductant and its versatility is a result of its ability to initiate a wide range of reductions including C-C bond-forming and cascade or sequential reactions. SmI 2 can reduce a variety of functional groups including sulfoxides and sulfones, phosphine oxides, epoxides, alkyl and aryl halides, carbonyls, and conjugated double bonds. [2][3][4][5][6][7][8][9][10][11][12] One of the fascinating features of SmI-2 -mediated reactions is the ability to manipulate the outcome of reactions through the selective use of cosolvents or additives. In most instances, additives are essential in controlling the rate of reduction and the chemo-or stereoselectivity of reactions. [13][14] Additives commonly utilized to fine tune the reactivity of SmI 2 can be classified into three major groups: (1) Lewis bases (HMPA, other electron-donor ligands, chelating ethers, etc.), (2) proton sources (alcohols, water etc.), and (3) inorganic additives (Ni(acac) 2 , FeCl 3 , etc). 3Understanding the mechanism of SmI 2 reactions and the role of the additives enables utilization of the full potential of the reagent in organic synthesis. The Sm-Barbier reaction is chosen to illustrate the synthetic importance and mechanistic role of two common additives: HMPA and Ni(II) in this reaction. The Sm-Barbier reaction is similar to the traditional Grignard reaction with the only difference being that the alkyl halide, carbonyl, and Sm reductant are mixed simultaneously in one pot. 1,15 Examples of Sm-mediated Barbier reactions with a range of coupling partners have been reported, 1,3,7,10,12 and have been utilized in key steps of the synthesis of large natural products. 16,17 Previous studies on the effect of additives on SmI 2 reactions have shown that HMPA enhances the reduction potential of SmI 2 by coordinating to the samarium metal center, producing a more powerful, [13][14]18 sterically encumbered reductant 19-21 and in some cases playing an integral role in post electrontransfer steps facilitating subsequent bond-forming events. 22 In the Sm-Barbier reaction, HMPA has been shown to additionally activate the alkyl halide by forming a complex in a pre-equilibrium step. 23Ni(II) salts are a catalytic additive used frequently in Sm-mediated transformations. [24][25][26][27] Though critical for success, the mechanistic role of Ni (II) was not known in these reactions. Recently it has been shown that SmI 2 reduces Ni(II) to Ni(0), and the reaction is then carried out through organometallic Ni(0) chemistry. 28These mechanistic studies highlight that although the same Barbier product is obtained, the use of different additives in the SmI 2 reaction drastically alters the mechanistic pathway of the reaction. The protocol for running these SmI 2 -initiated reactions is described. Video LinkThe video comp...

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Improved Reactivity of Diiodosamarium by Catalysis with Transition Metal Salts

Cited by 122 publications

References 0 publications

Barbier-Type Reactions of Cyclic Acid Anhydrides and Keto Acids Mediated by an SmI2-(NiI2-Catalytic) System – Preparation of Disubstituted Lactones

Barbier-Type Reactions of Cyclic Acid Anhydrides and Keto Acids Mediated by an SmI2-(NiI2-Catalytic) System – Preparation of Disubstituted Lactones

Investigation of Innovative Synthesis of Biologically Active Compounds on the Basis of Newly Developed Reactions

Preparation and Use of Samarium Diiodide (SmI<sub>2</sub>) in Organic Synthesis: The Mechanistic Role of HMPA and Ni(II) Salts in the Samarium Barbier Reaction

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