Tetrakis aluminate

Chemical Name Tetrakis(hydroxymagnesium)decahydroxydialuminate dihydrate Common Name Magnesium aluminate hydrate monalium hydrate Structural Formula [Mg(DH)]4 [(HD)4AI(DH)(HO)AI(OH)4]-2H2D Chemical Abstracts Registry No. 1317-26-6... 

After extensive experimentation, a simple solution for avoiding catalyst deactivation was discovered, when testing an Ir-PHOX catalyst with tetrakis[3,5-bis (trifluoromethyl)phenyl]borate (BArp ) as counterion [5]. Iridium complexes with this bulky, apolar, and extremely weakly coordinating anion [18] did not suffer from deactivation, and full conversion could be routinely obtained with catalyst loadings as low as 0.02 mol% [19]. In addition, the BArp salts proved to be much less sensitive to moisture than the corresponding hexafluorophosphates. Tetrakis (pentafluorophenyl)borate and tetrakis(perfluoro-tert-butoxy)aluminate were equally effective with very high turnover frequency, whereas catalysts with hexafluorophosphate and tetrafluoroborate gave only low conversion while reactions with triflate were completely ineffective (Fig. 1). 

Lithium aluminum hydride dissolves in pyridine and forms lithium tetrakis-(A -dihydropyridyl)aluminate which itself is a reducing agent for purely aromatic ketones [440, 441]. 

Heteroaromatics are subdivided, according to the electron influence of the heteroatom, into w-electron-deficient compounds and compounds with an excess of it electrons on the ring carbon atoms. The typical ff-electron-delicient compound pyridine has so far been made to react only in one case the reaction of lithium tetrakis(A-dihydropyridyl)-aluminate (LDPA) [112-114), obtainable from pyridine and lithium aluminum hydride, with trifluoromethanesulfenyl chloride in an excess of pyridine affords 3-trifluoromethylmercaptopyridine in low yield (13%) (60). This reaction probably occurs through sulfenylation of the l,2-dihydrop5T idyl moiety of the LDPA with the formation of a 2,5-... 

The lithium tetrakis (dihydrogenphosphido) aluminate, which is soluble in diglyme, shows typical organic and inorganic substitution reactions and can be used to introduce PH2 groups into molecules. The compound is quantitatively hydrolysed thus ... 

Lithium aluminum hydride reacts readily with pyridine to yield lithium tetrakis-(A/-dihydropyridyI)aluminate, LiAI(NR2)4 (structures 108 and 109).152 The NR2 groups represent 1,4-dihydro- and/or, 1,2-dihydropyridyl residues. The two diverse N-ligands may be part of the same molecule in association with the A1 metal. The structure of the adduct has been investigated by IR and NMR spectroscopy and by deuterium-labeling experiments. The latter approach has been used to determine the 1,2 to 1,4 ratio, which is found to be close to 1 2 when the reaction is carried out at room temperature. The N—A1 bond is assumed to be covalent, though of a markedly more ionic character as compared to the N—H bond in dihydropyridines.152... 

Dialkylamido complexes54 are generally more tractable than those containing NH2 groups. Lithium tetrakis(dimethylamido)aluminate is obtained by the reaction shown in equation (4).55... 

Tetrakis (N-dihydropyridyl) aluminate, 64 Thionyl fluoride, 462 Torsional strains, 71 19-Tosyloxyandrost-4-ene-3,17-dione, 198... 

Reaction of methanetellurol with lithium aluminum hydride in diethyl ether caused liberation of hydrogen and formation of lithium tetrakis[methyltelluro]aluminate. This compound was not isolated but reacted with silyl or germyl halides to give silyl or germyl methyl tellurium derivatives4. 

Lithium tetrakis[methyltelluro]aluminate, prepared from methanetellurol and lithium aluminum hydride, reacted with silyl, germyl, and stannyl halides at low temperatures to produce, for instance, methyl silyl tellurium derivatives1. 

Tris(trimethylsilyl)aluminum, AllSifCHOj] (1). The reagent is obtained as the THE complex by reaction of Hg(Si(CH,),]i with aluminum powder in THE (90% yield). Nonsolvated reagent is prepared by reaction of sodium tetrakis(trimethylsilyl)aluminate with AlCl, in pentane. It ignites spontaneously in air dec. at 50°."... 

The results were interpreted in terms of steric requirements of the actual reducing species. It was suggested that attack of BH4" proceeds exclusively along the 1,4-reduction mode, whereas alkoxyborohy-drides (formed as reaction products) prefer the 1,2-reduction mode. The pyridine borine itself does not reduce enones under the reaction conditions, but it inhibits formation of alkoxyborohydrides. - The same trend was observed with aluminum hydride reductions. When LiAlH4 was first reacted with pyridine to form lithium tetrakis(dihydro-N-pyridyl)aluminate, 1,4-reduction predominated. ... 

The silyl organoaluminum reagent (52) was prepared either by the addition of activated aluminum to a tetrahydrofuran solution of chlorotrimethylsilane, or by the treatment of sodium tetrakis(trimethyl-silyl)aluminate with aluminum chloride. Alternatively, ate complex (53) may be prepared by the addition of methyllithium to tris(trimethylsilyl)aluminum. ... 

Lithium aluminum hydride (LAH) reductions are carried out in aprotic solvents and give rise to the dihydro- and tetrahydropyridine derivatives. LAH reacts with both pyridines and pyridinium salts. It has been known for some time that aged ( 24 h) pyridine and LAH solutions form complexes of lithium tetrakis(A -dihydropyridinyl)aluminate (40, LDPA), - which is believed to consist of a mixture of the 1,2- and 1,4-dihydropyridines (by NMR). Indeed, LDPA itself has been used as a selective reducing agent for ketones and affords 3-substituted pyridines (41) on reaction with alkyl halides. 2,5-Dihydropyridines have been identified as intermediates in similar reactions. Kuthan and co-workers have shown that for 3,5-dicyan-... 

Lithium aluminum hydride-Pyridme [Lithium tetrakis(N-dihydropyridyl)aluminate, LDPA], 1, 599-600. 

In the course of the study of use of pyridine as solvent, Lansbury discovered that on dissolving powdered lithium aluminum hydride (0.5 g.) in pyridine (50 ml.) and letting the orange solution stand in a stoppered bottle for at least 24 hrs. one obtains a solution of anew, milder reducing agent NMR and IR data show that the substance lacks Al-H bonds and contains both 1,2- and 1,4-dihydropyridine groups bound to aluminum. It is regarded as tetrakis-(N-dihydropyridyl)-aluminate ... 

A ketone added to the aged solution is reduced effectively, but a carboxylic acid or ester is not reduced. This weak hydride donor is thus useful for the selective reduction of a keto acid to the corresponding hydroxy acid. Both intermolecular 2md intramolecular competition experiments with tetrakis-(N-dihydropyridyl)-aluminate showed that diaryl ketones are more reactive to this reagent than either dialkyl or aralkyl ketones. This relationship is the opposite of that found by H. C. Brown for reduction with sodium borohydride in isopropyl alcohol, where the order of reactivity is acetone > acetophenone > benzophenone. 

Treatment of cyclopropanecarbonyl chloride with excess of lithium tetrakis(trimethyl-silyl)aluminate in the presence of a catalytic amount of copper(I) cyanide gave cyclopropyl-carbonyltrimethylsilane in 89% yield. 

Tetrakis(2-furyl)- and tetrakis(2-thienyl)aluminates can be prepared by direct substitution of Na[AlH4] ... 

As discussed in 5.3.8.4, Li tetrakis(trimethylsilyl)aluminate complexes are available by the Hg-catalyzed reaction of McjSiCl with Li metal and Al. But the analogous Na and K compounds cannot by synthesized in this direct way. These compounds are formed by ... 

Unsolvated Al(SiMe3)3 can be made neither by the direct route, the Hg-catalyzed reaction of Me3SiCl with Al and Li, nor by reacting Hg(SiMej)2 with Al metal. Neither can the coordinated ether be removed from Al(SiMe3)3 solvated with EtiO or tetra-hydrofuran (THF). This product forms only by the reaction of alkali tetrakis(tri-methylsilyl)aluminate with AICI3 in pentane ... 

---