Tris scandium

Scandium, tetrakis(tropolone)-stereochemistry, 1,94 Scandium, tris(acetylacetone)-structure, 1. 65, 68 Scandium, tris(tropolonate)-structure, 1,68 Scandium aryloxides spectroscopy, 2, 346 Scandium chloride... 

Scott Oakes et al. (1999a, b) have shown how adoption of SC conditions can lead to a dramatic pressure-dependent enhancement of diastereoselectivity. In the case of sulphoxidation of cysteine derivatives with rert-butyl hydroperoxide, with cationic ion-exchange resin Amberlyst-15 as a catalyst, 95% de was realized at 40 °C and with SC CO2. By contrast, with conventional solvents no distereoselectivity was observed. Another example is the Diels-Alder reaction of acrylates with cyclopentadiene in SC CO2 at 50 °C, with scandium tris (trifluoromethanesulphonate) as a Lewis acid catalyst. The endoiexo ratio of the product was as high as 24 1, while in a solvent like toluene it was only 10 1. 

Moreover, a new type of catalyst, scandium tris(dodecyl sulfate) [Sc(03S0Ci2H25)3,Sc(DS)3] has been developed.62. The catalyst (a Lewis Acid-Surfactant Combined Catalyst, LASC) acts both as a catalyst and as a surfactant, and aldol reactions proceed smoothly in the presence of a catalytic amount of Sc(DS)3 in water, without using any organic solvents (Scheme 16). 

With these results in hand, we have next introduced new types of Lewis acids, e.g scandium tris(-dodecyl sulfate) (4a) and scandium trisdodecanesul-fonate (5a) (Chart 1).[1S1 These Lewis acid-surfactant-combined catalysts (LASCs) were found to form stable colloidal dispersions with organic substrates in water and to catalyze efficiently aldol reactions of aldehydes with very water-labile silyl enol ethers. 

Structural analysis of several octahedral Sc(III) complexes have recently been reported. The structure 44) of anhydrous scandium-tris-acetylacetonate, Sc(acac)3, consists of discrete Sc(CH3COCHCOCH3)3 entity, with slight deviation from Dz symmetry. The coordination polyhedron around Sc (III) is a distorted... 

The results mentioned above prompted us to synthesize a more simplified catalyst, scandium tris(dodecyl sulfate) (Sc(DS)3) [23,24]. This new type of catalyst, Lewis acid-surfactant-combined catalyst (LASC) , was expected to act both as a Lewis acid to activate the substrate molecules and as a surfactant to form emulsions in water. Eng-berts and co-workers also reported a surfactant-type Lewis acid, copper bis(dodecyl sulfate) (Cu(DS)2) [25]. Although they studied detailed mechanistic aspects of Diels-Alder... 

Preparation of scandium tris(tris(perfluorooctanesulfonyl)methide)... 

PrC45H , Praseodymium, tris(2,6-di-rerf-butyl-4-methylphenoxo)-, 27 167 O3SCC43HU, Scandium tris(2,6-di-rm-butyl-phenoxo)-, 27 167... 

Furthermore, we have introduced new types of Lewis acids, scandium tris(do-decyl sulfate) (5a) and scandium trisdodecanesulfonate (6a) (Chart 14-1) [36]. 

A related compound scandium tris(trifluoromethylsulphonyl)methanide, Sc[(F3CS02)3C]3 (scandium triflide) has been prepared and used as a catalyst in the nitration of o-nitrotoluene.209 Scandium triflide has proved to be a better catalyst than scandium triflate for the aromatic nitration of the electron deficient o-nitrotoluene. 

The conversion of meso epoxides to P-amino alcohols in high enantiomeric excess continues to be a rich area of research. The samarium binol catalyst 117, generates P-amino alcohols in excellent yield with good asymmetric induction (91%) <050L1023>. The combination of a chiral bipyridal ligand and scandium tris(dodecylsulfate), 118, provides a method to open meso epoxides in water <05OL4593>. This catalytic system provides the amino alcohols in excellent yield and with good enantioselectivity. 

Friedel-Crafts acylation. Scandium tris(perfluorobutanesulfonyl)methide is a multipurpose catalyst. Besides promoting Friedel-Crafts reactions, it is also useful in the Diels-Alder reaction and Meerwein-Ponndorf-Verley reduction. 

Scandium tris-/3-diketonates are monomers, in contrast to the lanthanide analogues which form oxygen-bridged dimers except in the cases of bulky j8-diketonates combined with smaller-radius lanthanides. Sc(acac)3 itself is a compound of some antiquity and has been studied by a number of authors.Other /3-diketonates are also known Sc(tfaa)3-3H20, Sc(hfaa)3, Sc(tta)3, Sc(baa)3, Sc(bza)3, ° Sc(dbm)3 and Sc(dpm)3 " (Htfaa = 1,1,1-tri-fluoroacetylacetone, Hhfaa = 1,1,1,5,5,5-hexafluoroacetylacetone, Htta = thienoyltrifluoro-... 

Supercritical carbon dioxide (SC-CO2) is an environmentally benign solvent that is providing a viable alternative to the traditional organic solvents. A Diels-Alder reaction between n-butyl acrylate and cyclopentadiene was investigated with the Lewis acid catalyst scandium tris (trifluoromethanesuffonate), primarily due to its solubility in SC-CO2 (Eq. 10-12) ... 

Related Reagents. Related polymer-supported scandium tri-flates, i.e. Nafion-Sc, MC Sc(OTf)3, PA-Sc-TAD, and a polymer-supported scandium that works efficiently in water. A Lewis acid-surfactant combined scandium catalyst, scandium tris(dodecylsulfate). ... 

ScOiC4iH , Scandium tris(2,6-di-tert-butyl-phenoxo), 27 167... 

When 2-dimethylamino-5-methylbenzyl lithium, or 5-tert-butyl-2-dimethyl-aminomethylphenyl lithium are reacted with ScClj, scandium tris(2-dimethylamino-5-methylbenzyl) or scandium tris(5-tert-butyl-2-dimethylaminomethylphenyl) are formed in the same way. 

Sc03C43Hg3, Scandium, tri8(2,6-di-tert butyipbenoxo)-, 27 167 Sc03C4,Hg9, Scandium, tris(2,6-di-tert butyl-4-metbylpbenoxo)-, 27 167 Sc2Cl2Si4C44Hg4, Scandium, tetrakis[if -l,3-bi8(trimetbyl8ilyl)cyciopentadienyljdi /i-cbloro-di-, 27 171... 

Ling, J., Zhu, W., Shen, Z., 2004. ControUing ring-opening copolymerization of e-caprolactone with trimethylene carbonate hy scandium tris(2,6-di- tert -butyl-4-methylphenolate). Macromolecules 37 (3), 758—763. 

Scandium tris(perfluorooctanesulfonyl)methide complex was immobilized in a fluorous phase as a recyclable catalyst for Mukaiyama aldol reaction (2). On the other hand, the catalytic activity of scandium could be significantly increased by the use of a continuous flow system compared with a batch system. For example, in per-fluoromethylcyclohexane, the aldol reaction of benzaldehyde withthe trimethylsilyl enol ether derived from methyl 2-methylpropannoate was completed within seconds in the presence of less than 0.1 mol% of Sc(N(S02CgFi7)2]3 [3]. 

As an extension of this study, a more simplified catalyst, scandium tris(dodecyl sulfate) (Sc(DS)3) has been developed (Scheme 12.62) [163]. 

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