Tris ytterbium

It has been shown that ytterbium tris-(l )-(-)-l,l -binaphthyl-2,2 -diyl phospho-nate can catalyze the reaction of aromatic aldehydes with Danishefsky s diene to... 

Ytterbium, trinitratotris(dimethyl sulfoxide)-structure, 1, 97 Ytterbium, tris(acetylacetone)(4-ammo-3-penten-stereochemistry, 1,81 Ytterbium complexes acetylacetone, 2,373 dipositive oxidation state hydrated ions, 3,1109 polypyrazolylborates, 2,255 Ytterbium(III) complexes ethyl glycinate, diacetate... 

Otera has reported that fluorous distannoxanes such as 23, which dissociate to give Lewis acidic species, catalyze transesterifications in or-ganic/fluorous solvent mixtures [8,9]. Although 23 was insoluble in toluene at room temperature, it dissolved at reflux and efficiently promoted the transformation in reaction D of Scheme 4, as well as others. The catalyst precipitated upon cooling, but a fluorous solvent extraction was utilized for recovery (100%). Another thermomorphic fluorous Lewis acid catalyst was developed by Mikami [11]. He found that the ytterbium tris(sulfonamide) 24 could be used for Friedel-Crafts acylations imder homogeneous conditions in CICH2CH2CI at 80 °C, and precipitated upon cooHng to -20 °C (reaction E, Scheme 4). 

A series of trivalent lanthanoid complexes, scandium, and ytterbium tris-(R)-(-)-1,1 -binaphthyl-2,2 -diyl phosphonate, have been introduced as new chiral and stable Lewis acids for the asymmetric hetero Diels-Alder reaction of Danishefsky s diene and aldehydes. 2,6-Lutidine was found to be an effective additive to improve the enantioselectivity up to 89% ee [66] (Eq. 8A.42). 

X 109 and 8. 9 x 109 s 1 for Ndm and Ybm, respectively. Both the above-described in-termolecular mechanism, as well as an intramolecular pathway in the ternary complex with aad which forms in solution, are responsible for the observation of NIR luminescence in these systems. Addition of water to the toluene solutions quenches the NIR luminescence, while it enhances the visible CL emission of the corresponding solution of Eum and Tbm (Voloshin et al., 2000c). Neodymium and ytterbium tris(benzoyltrifluoroacetonates) display the same CL as tta complexes, although for Ybm its intensity is about 2.5 times lower than for the tta chelate. On the other hand, almost no CL is detected for acetylacetonate complexes (Voloshin et al., 2000a). Thermal or photochemical decomposition of aad also triggers CL from [Pr(dpm)3] and Pr(fod)3], both in the visible (from the 3Pi, 3Po, and 1D2 levels) and in the NIR at 850 nm ( Do -> 3F2 transition) and 1100 nm ( D2 3F4 transition). The excited... 

Benzaldehyde (81 mg) and methyl trimethoxysilyl dimethylketene acetal (165 mg) were added to a mixure of 3 ml perfluorooctane and 4 ml toluene. To this mixture was added Imol % (based on benzaldehyde) ytterbium (tris(trisperfluorooctanesulfonyl)methide) and the reaction stirred 15 minutes at 40°C. Mixing and heating were stopped and the mixture separated into upper toluene layer and lower perfluorooctane layer. Each layer was analyzed by gas chromatography 99% of the product was detected in the lower layer. Atomic emission spectrometry indicated that at least 99% of the catalyst was also present in the lower layer. 

Preparation of ytterbium tris(tris(perfluorobutanesulfonyl)-methide)... 

The use of water as a solvent in the conjugate addition of 1,3-diketones was reported earlier [69] and applied more recently in organic synthesis [70]. Ytterbium tri-flate turned out to be an efficient catalyst for the Michael addition of various fj-kc-... 

Barrett, A. G. M., Braddock, D. G., Gatterick, D., Chadwick, D., Henschke, J. P., and McKinnell, R. M. 2000. Pluorous biphase catalytic Priedel-Crafts acylation ytterbium tris(perfluoroalkanesulfonyl)methide catalysts. Synlett 847-849. 

Yb03C45hj5, Ytterbium, tris(2,6-di-te -butyl-4-methylphenoxo)-, 27 167 Yb2Cl2Si4C44Hj4, Ytterbium, tetrakis[Ti -l,3-bis(trimethylsilyl)cyclopentadienylJdi-(i-chloro-di-, 27 171... 

The Friedel-Crafts acylation of arenes with acetic anhydride was efficiently catalyzed by ytterbium tris(per luoroalkanesulfonyl)methides 29a-29c [32]. Itwas demonstrated that catalyst 29c could be recovered in 96% yield by extraction of the reaction mixture with hot perfluoromethyldecalin and could be re-used in a second run. 

O3YC45HM, Yttrium, tris(2,6-di-terf-butyl-4-methylphenoxo)-, 27 167 0,YbC4sH , Ytterbium, tris(2,6-di-tert-bu-tyl-4-methyiphenoxo)-, 27 167 04A FeC22H,s, Iron, tetracarbonyl(tri-phenylarsine)-, 26 61 04BF4MoC H , Molybdenum(l +), (ace-tone)tricarbonyl(T) -cyclopentadienyl)-, tetrafluoroborate(l -), 26 105 O4BF4WC11H11, Tungsten(l +), (ace-... 

YbOjCgjHgg, Ytterbium, tris(2,6-di-(er(-butyl-4-methylphenoxoK 27 167 Yb2Cl2Si4C44Hg4, Ytterbium, tetraki [[Pg.463]

In this work, the mass spectrometric investigation of regularities during the vaporization of ytterbium tri-and dibromide was performed in order to determine the qualitative and quantitative composition of saturated... 

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