Ytterbium bromides

Molecular and Ionic Species in Vapor over Molten Ytterbium Bromides... 

A combination of cat. Ybt and A1 is effective for the photo-induced catalytic hydrogenative debromination of alkyl bromide (Scheme 28) [69]. The ytterbium catalyst forms a reversible redox cycle in the presence of Al. In both vanadium- and ytterbium-catalyzed reactions, the multi-component redox systems are achieved by an appropriate combination of a catalyst and a co-reductant as described in the pinacol coupling, which is mostly dependent on their redox potentials. 

In 2001, the preparation of allylytterbium bromide and the synthesis of homoallylic alcohols using allylytterbium bromide were reported.39 393 Ytterbium metal was found to be activated by a catalytic amount of Mel at 0 °C in THF to produce allylytterbium bromide 66 (Equation (11)). The allylation reaction of a wide range of aromatic aldehydes and ketones proceeded at ambient temperature or less in good to high yields (Table 2). Imines also reacted with allylytterbium bromide to afford homoallyl amines (Table 3). 

Bis[(nitrooxy)methyl]propane-l,3-diol dinitrate, 1895 Bis(2-nitrophenyl) disulfide, 3459 Bis(pentafluorophenyl)aluminium bromide, 3412 Bis(pentafluorophenyl)ytterbium, 3417 Bis(2,4-pentanedionato)chromium, 3320... 

In the presence of methyl iodide, metallic ytterbium can easily react with allylbromide in anhydrous THF to form allylytterbium bromide, which reacts readily with imines to give the corresponding bromoallylamines in satisfactory yields under mild and neutral conditions (Scheme 303).1091... 

Indoles react with epoxides and aziridines in the presence of Lewis acids (see section 17.5 for reaction of indolyl anions with such reactants) with opening of the three-membered ring and consequent 3-(2-hydroxyalkylation) and 3-(2-amino-alkylation) of the heterocycle. Both ytterbium triflate and phenylboronic acid are good catalysts for reaction with epoxides under high pressure " silica gel is also an effective catalyst, but slow at normal pressure and temperature." Lewis acid-mediated reaction with aziridines can be catalysed by zinc triflate or boron trifluoride.More reactive alkylating electrophiles react at lower temperatures, at room temperature with dimethylallyl bromide for example. ... 

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