Aluminium and Thallium

Aluminium and Thallium. - A new synthesis of triethylaluminium (as its diethyl etherate complex) has been achieved by ultrasonic irradiation 

Tri(isobutyl)aluminium has been used for the asymmetrisation of both 

Relatively little work has been published in the area of organo-thallium chemistry this year. Vinyl ketones have been shown to undergo efficient arylation, leading to B-aryl ketones, when treated 

Aluminium and Thallium.—Lithium trialkylhydroaluminates of the type Li RBu 2A1H are stereoselective reducing agents for cyclohexanones, and undergo addition to symmetrical diynes as indicated in reaction (2). The aluminium can be replaced by deuterium on treatment with D2O in the latter case. 

On addition of ethers or Bu Li to alkenyldialkylalanes the reactivity of the latter compounds is enhanced, and they may be used to transfer a nucleophilic alkenyl unit to an oxiran. Optically active methyloxiran has been employed in a reaction of this type as part of a stereoselective synthesis of (R)-recifeiolide.  

Treatment of alkylzirconium compounds (obtainable via hydrozirconation) with AICI3 provides a novel approach to alkylaluminium compounds which may then react with acyl chlorides to give unsymmetrical ketones.Alkylthio-, alkenylthio-, and dialkylamino-dialkylalanes react with esters to give the corresponding thio-esters or amides in fair to excellent yields. 

Arylthallium bis(trifluoroacetate)s are converted by successive treatment with KF and BF3 into aryl fluorides.Thallium(iii) nitrate (TTN) readily oxidizes dialkyl sulphides and selenides to the corresponding sulphoxides or selenoxides, and 2-(alkylthio)-l-arylethanones (37) into compounds (38) in methanolic solution.In a modification of the TTN oxidative conversion of aryl alkyl ketones into arylacetic acids, enol ethers derived from the ketones are used instead of the ketones themselves. This reduces the formation of side products. Cyclic aralkyl ketones (39) may be ring-expanded and alkylated to give compounds (40) via treatment of their Wittig-derived alkenes with TTN/ an extrapolation of the basic reaction discovered previously. 

Electron-rich aromatic compounds may be coupled to biaryls under the action of T1(0C0CF3)3, and the utility of this approach is illustrated in the synthesis of 

Aluminium and Thallium.- Two new reagents, methylaluminium bis(2,6-di - t-butyl-4-phenoxide) (MAD) (117), and methylaluminium bis(2,4,6-tri-t-butyl-4-phenoxide) (MAT) (118), have been prepared 

The nucleophilic properties of alanes have been exploited in some useful ways. Furanosyl and pyranosyl fluorides react with a 

A synthesis of trans-2,5-dlsubstituted tetrahydrofurans (120) has been developed that is based on the cyclization of U-alkenols 

2-Phenylindoles may be conveniently synthesized by reaction of a 2-thallated anilide with a Cu(I)-acetylide followed by cyclization 

Aluminium and Thallium.—The ( )-alkenyldialkylalanes which are obtained by hydroalumination of alkynes are synthetically useful as agents for transfer of the 

Reagents (i), BEt3-Bu C02H (ii), EljBH (iii), CH3COCH2C OCH3 

The chiral alkoxytrialkylaluminate, LiBu AlOR [R OH is (—)-A-methyle-phedrin (87)] allows transfer of the Bu group to carbonyl compounds with moderate (up to 30%) optical induction. (88 L == HMPT) can be used to oxidize trialkyla-lanes. Bu AlH can be used to catalyse the cyclization of polyenes, (89), for example, being obtained from (90) in quite good yield by this method.  

Hashimoto, Y. Kitagawa, S. lemura, H. Yamamoto, and H. Nozaki, Tetrahedron Letters, 1976, 2615. 

Uemura, H. Miyosht, A. Toshimitsu, and M. Okano, Bull. Chem. Soc. Japan, 1976, 49, 3285. 

The coupling reactions of organoaluminium reagents have again received attention, and have been extended to cover for example the substituted enol phosphates (104), which react with R3AI [catalysed by Pd(0)] to give, after hydrolysis, ketones (105). Similar methodology has been used to effect 1,2- and 1,3-carbonyl transpositions with concomitant alkylation. The scope of 

Itsuno, S. Nakahama, and N. Yamazaki, /. Chem. Soc., Chem. Commuiu, 1981, 315. 

OAlMea 0P(0R)2 OSiRs alkenyl aluminiums, prepared for example by the carboalumination of acetylenes, participate in this reaction with retention of stereochemistry to give 1,4-dienes. Aryl phosphates are found to have a reactivity similar to that of aryl chlorides in their reaction with organoaluminium reagents, and have been used to prepare alkyl, alkenyl, and aryl benzenes in a nickel-catalysed reaction.  

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The metals of the aluminium sub-group are permanent in the air at ordinary temperatures, but when heated in oxygen or the air they become coated with their oxide. The volatility of the metals increases with the atomic weights, and the heavier metals are more easily reduced than those of lower atomic weight. The metals are all malleable, fusible, have small atomic volumes and form hydroxides, M(OH)3, which are typically amphoteric in the first three elements of the sub-group and basic only in the case of thallium. The last four members of the family form alums, and both aluminium and thallium form organo-metallic compounds, resembling zinc in this respect. 

Slavin, W., Carnrick, G.R. and Manning, D.C. (1982). Graphite-tube effects on perchloric acid interferences on aluminium and thallium in the stabilized temperature platform furnace. Anal. Chim. Acta, 138,103-110. 

Aluminium and Thallium.—The main new reactions of organoaluminium compounds in C—C bond-forming processes continue to depend on four-co-ordinate aluminate complexes. Scheme 8 depicts some of the new reactions based on aluminates derived by hydroalumination of olefins using LiAlH4-... 

Aluminium and Thallium.—Acetylenes are carbometallated by the reagent system R3Al-[Cp2ZrCl2], giving rise to vinylalanes [e.g. (53)] which may be... 

Hydroboration and B—C Bond Formation Reactions of Organoboranes Reactions of Organoborates Reducing Agents Aluminium and Thallium... 

The first ionization energies of the Group II and Group III elements. There is a marked decrease between magnesium and barium, which is not matched by that between aluminium and thallium. 

Grjotheim, K., Krohn, C., Malinovsky, M., Matiaskovsky, K., and Thonstad, J., Aluminium Electrolysis—Fundamentals of the Hall-Herault process, CRC Press, Boca Raton, FL, 1982, 17. Palmear, I. J., in The Chemistry of Aluminium, Gallium, Indium, and Thallium, Downs, A. J., Ed., Blackie, London, 1993, 87. 

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