Lanthanide Triflates Research Articles

水溶液中でのルイス酸触媒反応

Rare earth metal trifluoromethanesulfonates (lanthanide and scandium triflates) were found to be stable Lewis acids in water and can act as Lewis acid catalysts in several carbon-carbon forming reactions In all cases, the reactions proceeded smoothly in the presence of a catalytic amount of the triflate under mild conditions in aqueous solution. For example, in the presence of a catalytic amount of rare earth metal triflate, formaldehyde in water solution (commercial formaldehyde solution) was activated and the hydroxymethylation reaction of silyl enol ethers proceeded smoothly Rare earth metal triflates were also quite effective in the aldol reaction of silyl enol ethers with aldehydes in aqueous media, and water-soluble aldehydes such as acetaldehyde, acrolein, and chloroacetaldehyde could be employed for direct use. Moreover, the allylation reaction of a wide variety of carbonyl compounds with tetraallyltin was successfully carried out in aqueous media by using scandium triflate as a catalyst. Unprotected sugars reacted directly to give the adducts in high yields. In all these reactions, lanthanide triflates were quantitatively recovered after the reactions were completed and could be reused.

ChemInform Abstract: Lanthanoid Triflates as Water‐Tolerant Lewis Acids. Activation of Commercial Formaldehyde Solution and Use in the Aldol Reaction of Silyl Enol Ethers with Aldehydes in Aqueous Media.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Lanthanoid Triflate Catalyzed Conjugate Addition of Amines to α,. beta.‐Unsaturated Esters. A Facile Route to Optically Active β‐ Lactam.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Study on the Catalytic Activities of Lanthanoid(III) Triflates in the Glycosylation of 1‐O‐Methoxyacetyl Sugar.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Repeated Use of the Catalyst in Ln(OTf)3-Catalyzed Aldol and Allylation Reactions

Abstract The lanthanoide trifluoromethanesulfonate (lanthanoid triflate)-catalyzed aldol reactions of silyl enol ethers with aldehydes and allylation reactions of tetraallyltin with aldehydes proceeded smoothly in a water–ethanol–toluene system. The reactions proceeded much faster in the above solvent than in water–tetrahydrofuran. Repeated use of the catalyst in these reactions was realized by a very simple procedure.

Lanthanide Triflates as Water-Tolerant Lewis Acids. Activation of Commercial Formaldehyde Solution and Use in the Aldol Reaction of Silyl Enol Ethers with Aldehydes in Aqueous Media

Lanthanide trifluoromethanesulfonates (triflates), especially ytterbium triflate (Yb(OTf) 3 ), were found to be stable Lewis acids in water. In the presence of a catalytic amount of lanthanide triflate, formaldehyde in water solution (commercial formaldehyde solution) was activated and the hydroxymethylation reaction of silyl enol ethers proceeded smoothly. Lanthanide triflates were also quite effective in the aldol reaction of silyl enol ethers with aldehydes in aqueous media; and watersoluble aldehydes such as acetaldehyde, acrolein, and chloroacetaldehyde could be employed for direct use. Moreover, in all these reactions, lanthanide triflates were quantitatively recovered after the reactions were completed and could be reused

Lanthanoid Triflate Catalyzed Conjugate Addition of Amines to α, β-Unsaturated Esters. A Facile Route to Optically Active β-Lactam

Abstract Catalytic amount of lanthanoid(III) triflates promoted the conjugate addition of amines to 2-alkenoic acid esters to give β-amino esters. The reaction of benzylamine with α,β-unsaturated esters containing a stereogenic center at γ-position proceeded diastereoselectivity to yield optically active β-lactam precursors.

Cyclooctatetraenyl-komplexe der frühen übergangsmetalle und lanthanoide: III. Cyclooctatetraenyl-lanthanoidtriflate und -iodide: Neue ausgangsmaterialien für die organolanthanoid-chemie

The dimeric complexes [(COT)Ln(μ-O 3SCF 3)(THF) 2] 2 (Ln  Ce ( 1), Pr ( 2), Nd ( 3), Sm ( 4)) are easily prepared by treatment of anhydrous lanthanide(III) triflates with equimolar amounts of K 2COT (COT = η 8-cyclooctatetraenyl(2−)). The reaction of lanthanide triiodides with K 2COT affords monomeric complexes of the type (COT)Ln(I)(THF) 3 (Ln  Nd ( 5), Sm ( 6)). Due to their increased solubility in polar organic solvents these new precursors offer preparative advantages over the previously used chloro derivatives [(COT)Ln(μ-Cl)(THF) 2] 2. The molecular structures of 3 and 5 have been determined by X-ray diffraction.

Facile Isomerization of Trimethylsilyl Ketene Acetals to α-Trimethylsilyl Esters Catalyzed by Lanthanoid Trifluoromethanesulfonates

Abstract Migration of trimethylsilyl group from oxygen to α-carbon in silyl ketene acetals is effectively catalyzed by lanthanoid triflates under mild conditions. Scope and limitation of this rearrangement are presented.

Lanthanide(III) trifluoromethanesulfonates as extraordinarily effective new catalysts for the aminolysis of 1,2-epoxides

Lanthanide(III) trifluoromethanesulfonates (triflates), such as Yb(OTf) 3, Nd(OTf) 3 and Gd(OTf) 3, catalyze in a extraordinarily efficient way the aminolysis of 1,2-epoxides, affording the corresponding β-amino alcohols, at room temperature and in a non-protic solvent (CH 2Cl 2 or toluene), in very good yields. The reactions are completely anti stereoselective and highly regioselective.

Asymmetric Diels-Alder reactions catalyzed by chiral lanthanide(III) trifluoromethanesulfonates. Unique structure of the triflate and stereoselective synthesis of both enantiomers using a single chiral source and a choice of achiral ligands

Chiral lanthanide trifluoromethanesulfonates (triflates) were developed and the unique structure of the triflates was revealed. In the presence of a catalytic amount of the triflate, acyl-1,3-oxazolidin-2-ones reacted with cyclopentadiene to afford the Diels-Alder adducts in high yields and with high enantiomeric excesses. According to the reactions, both enantiomers of the Diels-Alder adducts were stereoselectively prepared by using a single chiral source, R-(+)-binaphthol, and a choice of achiral ligands. When 3-acetyl-1,3-oxazolidin-2-one was combined with the original catalyst system consisting of lanthanide triflate, R-(+)-binaphthol, and cis-1,2,6-trimethylpiperidine, a new catalyst was generated (catalyst A). In the presence of this catalyst, 3-acyl-1,3-oxazolidin-2-ones reacted with cyclopentadiene to afford the endo adducts in high enantiomeric excesses. The absolute configuration of the products was 2S, 3R. On the other hand, when 3-phenylacetylacetone (PAA) was mixed with the original catalyst system (catalyst B), reverse enantiofacial selectivities were observed and endo adducts with the absolute configuration 2R, 3S were obtained in high enantiomeric excesses.

Preparation and Reaction of Lanthanide(II) Trifluoromethanesulfonates

Samarium(II) trifluoromethanesulfonate (triflate) and ytterbium(II) triflate are conveniently and cleanly prepared as a tetrahydrofuran solution from samarium(III) triflate and ytterbium(III) triflate, respectively, by treating them with ethylmagnesium bromide at room temperature.

Scandium Trifluoromethanesulfonate. A Novel Catalyst for Friedel-Crafts Acylation

Scandium trifluoromethanesulfonate (Sc(OTf)3) was found to be a novel catalyst for Friedel-Crafts acylation. The reactions of substituted benzenes with acid chlorides or anhydrides proceeded smoothly even in the presence of a catalytic amount of Sc(OTf)3. While Sc(OTf)3 is a reusable catalyst similar to lanthanide trifluoromethanesulfonates, its catalytic activity is much higher than that of lanthanide analogs.

Highly Coordinated Lanthanoid–Phosphane Complexes

More and more lanthanoid–phosphorus bonds and a wide variety of structure variations are found in the complexes prepared from the phosphinomethanide Li[C(PMe2)2(SiMe3)] and lanthanoid triflates. In the homoleptic scandium complex 1, for example, the ligands are bound in a mode intermediate to σ and π coordination.

Lanthanide(III) trifluoromethanesulfonate complexes in anhydrous acetonitrile

Anhydrous solutions of lanthanide(III) trifluoromethanesulfonates (triflates) in acetonitrile have been prepared and studied. Solubility measurements revealed that among the salts considered (Ln(SO 3CF 3) 3; LnLaLu) only the heavier ones (LnDyLu) are soluble (S>150 mmol dm −3) in strictly anhydrous conditions. Additions of small quantities of water proved that the solubility of lighter salts depends strongly on the presence of this reagent in solution. The ability of the triflate ion to coordinate the tervalent lanthanides in anhydrous solutions has been investigated by means of conductometric and FT-IR techniques. Quantitative IR measurements allowed detection of the main species in solution to be Ln(SO 3CF 3) 2 + and Ln(SO 3CF 3) 3. Their apparent equilibrium constants are reported. The competition of perchlorate and triflate for the Ln(SO 3CF 3) 2 + ion has also been studied. Measurements of the formation constant of the mixed complex, Ln(SO 3CF 3) 2ClO 4, suggested that the affinity of the perchlorate ion for the Ln(SO 3CF 3) 2 + complex is about ten times lower than that of the third triflate. The effects of added water or dimethyl sulfoxide on the dissociation of the triflate complexes in AN were also obtained.

Lanthanoid(III) triflates as new glycosylation catalysts. Selective and efficient activation of 1-O-methoxyacetyl sugars

Abstract The reactions of 1-O-methoxyacetyl sugars with alcohols or thiols were effectively promoted by a catalytic amount of lanthanoid(III) triflates such as Tb(OTf)3, Ho(OTf)3, Tm(OTf)3, and Yb(OTJ)3 to give the corresponding glycosides in good to excellent yields.

Lanthanide Trifluoromethanesulfonates as Reusable Catalysts: Aldol Reactions in Organic Solvents

The aldol reaction of silyl enolates with aldehydes or acetals using a lanthanide trifluoromethanesulfonate as catalyst smoothly proceed in organic solvents to afford the corresponding aldol-type adducts in high yields. The catalyst can be easily recovered after the reaction is completed, and yields of the 2nd run of the catalyst are comparable to those of the 1st run

Lanthanide trifluoromethanesulfonates as reusable catalysts: catalytic Friedel-Crafts acylation

The Friedel-Crafts acylation of substituted benzenes proceeds smoothly by using a catalytic amount of a lanthanide trifluoromethanesulfonate [Ln(OTf)3], which is easily recovered from the reaction mixture and reused without a decrease in catalytic activity.

１‐Ｏ‐メトキシアセチル糖のグリコシル化反応におけるランタノイド（ＩＩＩ）トリフラートの触媒活性に関する研究

he catalytic activities of a series of lanthanoid(11) triflates in the glycosylation of 1-0methoxyacety1-2, 3, 4, 6-tetra-0-benzyl-D-glucopyranose with 1-octanol (Eq.1) were investigated. As shown in Table 1, the triflates of some heavy lanthanide(II) salts such as Tb (OTf)3, Ho(OTf)3, Tm(0Tf)3, and Yb(OTf)3, were found to be highly effective. However, there seems to be no clear correlation between the catalytic activity and either the ionic radius or the oxophilicity of the lanthanoid metal ion.

The Aldol Reaction of Silyl Enol Ethers with Aldehydes in Aqueous Media

The aldol reaction of silyl enol ethers with aldehydes is successfully carried out in aqueous media by using a lanthanide trifluoromethanesulfonate as a catalyst. Water soluble aldehydes are applicable and the catalyst can be recovered and reused in this reaction.