Trialkylaluminum reagent

S)-phenylglycine have been used in the copper-catalysed conjugate addition of MeLi to enones. Trialkylaluminum reagents were also involved in only a few reactions, but these represent an interesting alternative. 

The detailed mechanism of the catalysis is not known, but it is believed that the Lewis acid character of the zirconium is critical.223 The reaction is further accelerated by inclusion of partially hydrolyzed trialkylaluminum reagents known as alumoxanes.224... 

The use of bulky trialkylaluminum reagents, such as Al( Bu)3, with various group 4 metallocenes led to olefin-polymerization catalysts that rivaled those formed with MAO as the co-catalyst. 

Mechanism of Reduction of Ketones with Trialkylaluminum Reagents. 

The chiral trialkylaluminum reagent used in the majority of asymmetric reduction studies is (+ )-tris[(S)-2-methylbutyl]aluminum (119) or its etherates. This reagent is readily prepared from (S)-( + )-2-methyl-l-chlorobutane (152,153). Results of the reductions of prochiral ketones with these reagents and other chiral organoaluminum reagents are shown in Table 15. 

Scheme 5 Synthesis of (//6-arcnc)l,nfAlCl4j3 (Ln = Y, Pr, Nd, Sm, Gd) subsequent reaction with trialkylaluminum reagents Me3Al or Et3Al gives alkylated ( 6-arene) Ln(AlCl3R)3 (R = Me, Et) compounds in good yields [105]...

Although alkoxide alkylaluminum adduct formation seems to be the preferred reaction pathway of lanthanide alkoxides with trialkylaluminum reagents, the corresponding reaction of decamethylytterbocene derivative (C5Me5)2Yb(Of-Bu)(NH3) takes a different course. Addition of three equivalents of MC3AI yielded a purple 2 1-adduct as confirmed by elemental analysis and ll NMR spectroscopy. On the basis of the X-ray crys-... 

Fig. 2 Reactivity of lanthanide phenolates toward trialkylaluminum reagents R3AI...

It is well known that a variety of aluminum hydride reagents cleave acetal substrates with excellent stereoselectivities. It is not surprising, therefore, that similar experiments have been attempted with trialkylaluminum reagents. Equation (11) outlines the generalized transformation. 

Tin halides can be alkylated also with organoaluminium reagents.17 This method is seldom used in the laboratory, but it has been recommended as a method for removing organotin residues, R3SnX, from reaction mixtures.18 On the industrial scale, it has been used for making tetrabutyltin and tetraoctyltin, as the trialkylaluminum reagents are... 

Trimethylaluminum reacted with l-(2-phenylcyclopropyl)ethylacetate (3) to give trans-5-phenyl-2-hexene (4) in 86% yield. Similar results were obtained with other trialkylaluminum reagents. The first step presumably involves electrophilic attack of the aluminum at oxygen. 

The strong F—A1 interaction sometimes induces the abstraction of fluoride anion from the carbon-fluorine bond, which is not easy because of the strong C—F bond as shown in 3 (Scheme 3.15). Trialkylaluminum reagents are therefore useful for the C—F bond activation. Alkylation at the tertiary carbon of 4 with ketenesilylacetal (5) is such an example (Scheme 3.16) [2]. 

A new method for obtaining chiral -substituted carboxylic acids consists of S 2 ring openings of the tartramide-derived acetals (1) by trialkylaluminum reagents followed by cleavage of the major... 

The Nicholas reaction, that is, the addition reaction include amines, water, alcohols, trialkylaluminum reagents, of nucleophiles to cobalt-complexed propargylic cations, sodium borohydride, diethylaluminum cyanide, trialkylsilyl... 

When sterically more demanding trialkylaluminum reagents (R = i-butyl or 2-phenyl-propyl) are allowed to react with 9 a in diethyl ether or n-hexane, the cyclooligomerization process ends at the 1 3 compounds 82 (Scheme 6-21) [65J. The compounds have the structure of a triphosphametallahomobenzvalene, as has been confirmed for the case of R = CH2—CHPh —CH3 by X-ray crystallography. A plausible mechanistic rationale for the product formation involves a two-fold 1,2-addition of the triorganoaluminum to two equivalents of phosphaalkyne 9a (- 84). This is followed by a crossed [2 + 2]-cycloaddition... 

Scheme 6-21 Metallatriphosphahomobenzvalenes 82 by cyclotrimerization of fer -butylphosphaacetylene with trialkylaluminum reagents.

Another way to generated vinyl alanes is the transition metal catalyzed addition of trialkylaluminum reagents to alkynes. In Hoye s synthesis of elenic acid, 10 1-dodecyne was treated with Me3Al in the present of Cp2ZrCl2 and then MeLi. The resulting ate complex 730 was then reacted with triflate 731 to give a 96% yield of the alkene, 732. 

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