Reduction and coupling reactions of carbonyl compounds using samarium metal in aqueous media

Difunctionalization of Alkynones by Base-Mediated Reaction with α,α-Dithioketones

A novel 1,2-difunctionalization of alkynones via an umpolung strategy for the synthesis of tetrasubstituted olefins has been developed. This procedure is realized by a formal C-C σ-bond cleavage reaction of cyclic α,α-dithioketones and subsequent deprotection. Notable features of this approach include excellent yields, mild reaction conditions, a broad substrate scope, and operational simplicity.

Samarium-based Grignard-type addition of organohalides to carbonyl compounds under catalysis of CuI

Grignard-type additions were readily achieved under the mediation of CuI (10 mol%) and samarium (2 equiv.) by employing various organohalides, e.g. benzyl, aryl, heterocyclic and aliphatic halides (Cl, Br or I), and diverse carbonyl compounds (e.g. carbonic esters, carboxylic esters, acid anhydrides, acyl chlorides, ketones, aldehydes, propylene epoxides and formamides) to afford alcohols, ketones and aldehydes, respectively, with high efficiency and chemoselectivity, in which the organosamarium intermediate might be involved.

A convenient pinacol coupling of diaryl ketones with B2pin2via pyridine catalysis

A practical pinacol coupling of diaryl ketones is developed by employing a stable diboron reagent and pyridine Lewis base catalyst. The operationally simple process affords the desired diols with excellent efficiency in up to 99% yield within 1 hour.

Trace amount of metallic samarium catalysed aroyl substitution reactions of a β-keto ester in air

Catalysed by a trace amount of metallic samarium, a β-keto ester can react readily with aroyl chlorides to afford 3-oxo-arylpropionic acid esters in good yields. The reaction proceeds in air with toluene as solvent, which is not purified before use.

A New Method for the Synthesis of γ-Oxobutyronitriles via Addition of Aroyl Chlorides to Acrylonitrile Promoted by Samarium Metal in DMF

Without any pretreatment or activator, metallic samarium in DMF promotes the addition of aroyl chlorides to acrylonitrile to form γ-oxobutyronitriles

Catalytic Friedel–Crafts acylation of aromatic ethers using SmI3

10% mol SmI3 catalysed the Friedel–Crafts acylation of aromatic ethers by acyl chlorides in acetonitrile with the yields of 48–82%. Reactions of various substituted aromatic ethers with acyl chloride were studied. The structures of compounds were established by IR and 1H NMR. The main product obtained with anisole is the para-substituted compound with only a trace (<5 %) of meta and ortho substituted products. This shows that the acylation of aromatic ethers is highly regioselective in the presence of SmI3, a pattern repeated with the other aromatic ethers used.

Near theoretical ultra-high magnetic performance of rare-earth nanomagnets via the synergetic combination of calcium-reduction and chemoselective dissolution

Rare earth permanent magnets with superior magnetic performance have been generally synthesized through many chemical methods incorporating calcium thermal reduction. However, a large challenge still exists with regard to the removal of remaining reductants, byproducts, and trace impurities generated during the purifying process, which serve as inhibiting intermediates, inducing productivity and purity losses, and a reduction in magnetic properties. Nevertheless, the importance of a post-calciothermic reduction process has never been seriously investigated. Here, we introduce a novel approach for the synthesis of a highly pure samarium-cobalt (Sm-Co) rare earth nanomagnet with near theoretical ultra-high magnetic performance via consecutive calcium-assisted reduction and chemoselective dissolution. The chemoselective dissolution effect of various solution mixtures was evaluated by the purity, surface microstructure, and magnetic characteristics of the Sm-Co. As a result, NH₄Cl/methanol solution mixture was only capable of selectively rinsing out impurities without damaging Sm-Co. Furthermore, treatment with NH₄Cl led to substantially improved magnetic properties over 95.5% of the M_s for bulk Sm-Co. The mechanisms with regard to the enhanced phase-purity and magnetic performance were fully elucidated based on analytical results and statistical thermodynamics parameters. We further demonstrated the potential application of chemoselective dissolution to other intermetallic magnets.

A simple and practical catalytic electron transfer system composed of TiCl4 and metallic Yb: application in carbonyl olefination and insight into the mechanism

A simple and practical catalytic electron transfer system composed of TiCl₄ and Yb, which turned out to be effective for homo- and cross-deoxygenative coupling of aldehydes and ketones was developed. Mechanistic data provide an insight into the rate-determining step and intermediates.

Samarium(II)-mediated pinacol coupling in water: occurrence of unexpected disproportionation and action of low-valent samarium as an active species

[reaction: see text] Mechanistic studies of one-electron reduction in water using samarium were carried out. Unexpected disproportionation in water was observed via UV-vis spectroscopic analysis. This fact indicates that low-valent samarium species can exist in water. Furthermore, the SmCl(3)-Sm and SmCl(3)-Mg systems were found to act as good one-electron reducing agents in water.