Jean-Louis Namy

Efficient formation of pinacols from aldehydes or ketones mediated by samarium diiodide

Abstract Samarium diiodide is an excellent reagent for aldehyde or ketone coupling. With aromatic aldehydes, reactions are very fast with a complete selectivity versus substituents such as cyano, carboxyl or nitro groups.

Some organic reactions promoted by samarium diiodide

Abstract Various homoallylic alcohols and homobenzylic alcohols were prepared by the reaction between aldehydes and allylic or benzylic halides in the presence of samarium diiodide. This iodide is also a very good reagent for formation of pinacols from aldehydes or ketones. The reactions are especially fast and selective in the case of substituted benzaldehydes. The reactivities of various nitrogen functional groups (imine, oxime, nitro, azo, cyano) towards SmI2 were also examined.

Divalent lanthanide derivatives in organic synthesis—II

Abstract Aprotic THF solutions of SmI2 reduce aikyl halides or tosylates into the corresponding alkanes free of coupling products. The mechanism of this reaction involves an electron transfer from samarium to halides and hydrogen abstraction from THF. Aldehydes are selectively reduced by SmI2 in presence of a proton donor. Ketones react with organic halides in the presence of SmI2 giving tertiary alcohols. Mechanisms of these reactions are discussed. Some evidence including catalytic effects of FeCl3 are given for electron transfers from SmI2 towards ketones and halides.

Reactions of acyl anions generated from acid chlorides and diiodosamarium

Abstract Acid chlorides react with SmI 2 to give α-diketones. Various experiments show that the initially formed acyl radical is rapidly transformed into an acyl anion which is thus generated by quite an unusual route. This species acylates acid chlorides, aldehydes and ketones in situ to give α-diketones and α-ketols. There are some limitations to this acyl anion chemistry but the reactions are realized with a good efficiency at room temperature in THF solution.

Samarium diiodide/nickel diiodide an efficient system for homo and heterocoupling reactions of imines

Abstract Samarium diiodide in the presence of a catalytic amount of nickel diiodide mediates a very fast dimerization of imines into vicinal diamines and the mixed coupling of imines and ketones to give β-amino alcohols.

A new preparation of lanthanide alkoxide, and some applications in catalysis.

A new route to lanthanide tris(alkoxides) is described. These compounds are easily prepared by reaction of n-BuLi with corresponding adducts LnCl3, (3–4 ROH) that are obtained from hydrated LnCl3. They are efficient as catalysts in epoxidation of allylic alcohols by TBHP and in Meerwein-Ponndorf-Verley-Oppenauer reactions.

Samarium dibromide, an efficient reagent for the pinacol coupling reactions

Abstract The preparation of SmBr 2 from Sm 2 O 3 is described. This samarium (II) compound is a powerful one electron reluctant able to very efficiently mediate pinacolic couplings. Cross couplings are effective in some cases, for example a chiral diol can be obtained from benzophenone md camphor. Intramolecular pinacolization of a diketone has also been performed.

Samarium diiodide as coupling agent between aldehydes and organic halides for the synthesis of homoallylic and homobenzylic alcohols

Abstract Many aliphatic aldehydes are transformed into secondary alcohols by reaction with allyl halides or benzylic halides in presence of SmI2.

Samarium diiodide in tetrahydropyran : preparation and some reactions in organic chemistry

Abstract SmI 2 could be readily prepared in tetrahydropyran (THP) from samarium and 1,2-diiodoethane. Reducing properties were studied, showing marked differences compared to the classical SmI 2 /THF system.

Selective catalyzed-rearrangement of terminal epoxides to methyl ketones

Abstract Terminal epoxides of the type have been selectively converted into methyl ketones by various catalysts. Some lanthanide derivatives, MnI 2 , and Co 2 (CO) 8 gave the best results. The rearrangement of internal epoxides into ketones is much slower, allowing specific transformation of terminal epoxides. The scope of the reaction and tentative mechanisms are discussed.