Methoxide, aluminum

Aluminum methoxide Al(OMe)3 is a solid which sublimes at 240 °C in vacuum. Aluminum isopropoxide melts in the range 120-140 °C to a viscous liquid which readily supercools. When first prepared, spectroscopic and X-ray evidence indicates a trimeric structure which slowly transforms to a tetramer in which the central Al is octahedrally coordinated and the three peripheral units are tetrahedral.162,153 Intramolecular exchange of terminal and bridging groups, which is rapid in the trimeric form, becomes very slow in the tetramer. There is MS and other evidence that the tetramer maintains its identity in the vapour phase.164 Al[OCH(CF3)2]3 is more volatile than Al[OCH(Me)2]3 and the vapour consists of monomers.165 Aluminum alkoxides, particularly Al(OPr )3, have useful catalytic applications in the synthetic chemistry of aldehydes, ketones and acetals, e.g. in the Tishchenko reaction of aldehydes, in Meerwein-Pondorf-Verley reduction and in Oppenauer oxidation. The mechanism is believed to involve hydride transfer between RjHCO ligands and coordinated R2C=0— A1 groups on the same Al atom.1... 

This reducing agent is prepared in quantitative yield by the reaction of lithium tri-methoxyaluminum hydride (LTMA, 1, 625 2, 252-253) with the highly hindered tri-sec-butylborane in THF at 25°. Aluminum methoxide is also formed, but since it is inert, the reaction mixture can be used directly.1... 

Wisniewski, M. Le Borgne, A. Spassky, N. Synthesis and properties of (d)- and (L)-lactide stereocopolymers using the system achiral Schiff s base/aluminum methoxide as initiator. Macromol. Chem. Phys. 1997,198, 1227-1238. 

Dialkylborane-aluminum methoxide complex as intermediate 23, 702 suppl. 26 Dialkylchloroboranes as intermediates 27, 485 28, 783 prepn. 27, 649 N -Dialkylformamides s. Dimethylformamide N,N -Dialkylidene-1,1-diamines... 

Epoxide polymerization catalysts of quite different characteristics are those constituted by the metalloporphyrins of aluminum and zinc, such as (5,10,15,20-tetraphenylporphinato)aluminum chloride ((TPP)AICI), (5,10,15,20-tetraphenylporphinato) aluminum methoxide ((TPP)AlOMe) (see Scheme 27), and (5,10,15,20-tetraphenyl-21-methylporphinato)zinc methoxide ((MTPP)ZnOMe). ° ... 

Methyl-4-hydroxyquinazoline reacts with organic halides, in the presence of sodium methoxide, to give 3-substituted 2-methyl-4(3i/)-quinazolinones. The 0-acetyl derivative of 4-hydroxyquinazoline has been prepared under anhydrous conditions and gives the hydroxy compound with water or with lithium aluminum hydride. The N-3 acetyl derivative, however, is more stable and gives 3-methyl-4(31/)-quinazolinone with lithium aluminum hydride. ... 

Reduction of the 1//-1,2-benzodiazepines 6 with lithium aluminum hydride results in the dihydro compounds 8, which are dehydrogenated to the 3H-1,2-benzodiazepines 9 by 4-phenyl-4//-l,2,4-triazole-3,5-dione.123 The products readily revert to the 1//-tautomers in the presence of sodium methoxide. 3//-1,2-Benzodiazepines react with 3-chloroperoxybenzoic acid to give mixtures of 1- and 2-oxides, 10 and 11, in which the latter predominate. Treatment of the 2-oxides 11 with nucleophiles provides 3-substituted H- 1.2-benzodiazepines 12. Selected examples are given.124... 

To an ice-cold solution of the aldehydo sugar in CH,OH (ca. 25 mL per g) are added 3 equiv of nitromethane (or nitrocthane), followed by 2.9 equiv of sodium methoxide. After stirring for 2 h 45 min, the medium is neutralized by the addition of acidic Dowex 50, then filtered. Removal of the solvent by distillation and purification by chromatography on silica gel (Ei,0/hcxane) or on aluminum oxide (Et20) furnishes the product yield 85-99%. 

A (Alternative) JCS 3175(1952). 2 g 3-indolyl-acetic acid (preparation given elsewhere here), 1.55 g freshly fused sodium acetate, 5 ml acetic anhydride. Heat 135-140° on oil bath for eighteen hours cool, wash with water and extract with CHCl3-ether (1 4). Wash organic phase with 3X20 ml saturated KHC03 and dry, evaporate in vacuum to get the l-acetyl-3-indolyl-acetone, which can be reduced to the alpha-methyl-tryptophol derivative with lithium aluminum hydride, and then converted to the dialkyl-tryptamine as already described (as can (I)), or used in step B, or reduced to (I) as follows dissolve 1 g in 1 ml 1 N Na-methoxide in methanol and 60 ml methanol, and keep at 40° for 10 minutes acidify with dilute HC1 and extract with ether. Dry, evaporate in vacuum to get (I) (recrystallize-methanol). 

Aluminum porphyrins with alkoxide, carboxylate, or enolate can also activate CO2, some catalytically. For example, Al(TPP)OMe (prepared from Al(TPP)Et with methanol) can bring about the catalytic formation of cyclic carbonate or polycarbonate from CO2 and epoxide [Eq. (6)], ° - and Al(TPP)OAc catalyzes the formation of carbamic esters from CO2, dialkylamines, and epoxide. Neither of the reactions requires activation by visible light, in contrast to the reactions involving the alkylaluminum precursors. Another key difference is that the ethyl group in Al(TPP)Et remains in the propionate product after CO2 insertion, whereas the methoxide or acetate precursors in the other reactions do not, indicating that quite different mechanisms are possibly operating in these processes. Most of this chemistry has been followed via spectroscopic (IR and H NMR) observation of the aluminum porphyrin species, and by organic product analysis, and relatively little is known about the details of the CO2 activation steps. 

Synthesis ofLysergic Acid, By reacting N-benzoyl-3-(B-carboxyethyl)-dihydroindole (see JCS, 3158 (1931) for the preparation of this compound) with thionyl chloride, followed by aluminum chloride gives l-benzoyl-5-keto-l,2,2a,3,4,5-hexahydrobenzindole. This is then brominated to give the 4-bromo-derivative, which is converted to the ketol-ketone by reacting with methylamine acetone ethylene ketol. This is then hydrolized by acid to yield the diketone and treated with sodium methoxide to convert it to the tetracyclic ketone. Acetylate and reduce this ketone with sodium borohydride to get the alcohol, which is converted to the hydrochloride form, as usual. 

A variety of other anionic initiators promote the polymerization of thio-carbonyl fluoride. Among them are aluminum isopropoxide, di(hydrogenated tal-low)dimethylammonium methoxide and chloride, N-nitrosodimethylamine, diisopropylamine, and triethylamine (59). Combinations of either [(C6H 5)3 P] 3RhCl or... 

NOTE Substituting sodium methoxide for aluminum isopropoxide gave poor yields. 

Conversion of the phenoxypropanoic acid into the acid chloride enhances the ease of cyclization and the use of phosphorus pentachloride and aluminum chloride provides an example of this technique (51JA4205). The formation of 3-aminochroman-4-one has been achieved in this way starting from 2-amino-3-phenoxypropanoic acid (76TL271). Cyclization of the phenoxyethanoic acid shown in Scheme 234 occurs on reaction with sodium methoxide to give the chroman-3-one (63JCS5322). 

Borane-Dimethylamine, 42 Dimethyl phenylsilane, 123 Diphenylsilane, 153 Lithium aluminum hydride-Sodium methoxide, 159 Potassium-Graphite, 252 Raney nickel, 265 Sodium borohydride, 278 Sodium borohydride-Molybdenum(VI) oxide, 279... 

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